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1
A. A., Yuldashov, and Karimov G. X. "Models of Distribution of Flow Parameters in Intensive Garden Irrigation, System Pipes." International Journal for Research in Applied Science and Engineering Technology 10, no. 3 (March 31, 2022): 838–44. http://dx.doi.org/10.22214/ijraset.2022.40692.
Повний текст джерелаАнотація:
Annotation: The mathematical description of the movement of water in the systems of irrigation pipelines, based on the equation of continuity of the medium, the system of Navy-Stokes equations. The resulting mathematical package describes a system with distributed parameters and is performed based on the condition of dynamic balance at the point of flow, taking into account the dependence on the nature of the flow and the physical properties of the environment. Calculation is executed with use of functions Besseliya. Methodology for calculating the hydrodynamic component of water movement in irrigation water supply systems. Pipelines are universal in nature and can be used in the calculation, construction and assessment of the stability of water supply hydraulic systems; the technique can be used to describe the object of operation in the construction of control systems for the hydraulic parameters of the water supply system. Keywords: pipeline, irrigation systems, non-uniformity, liquid, water, strength, function, three-dimensional, water supply, hydrodynamics, hydrostatics, quasi-one-dimensional, unsteady, flow, potential, surface, coordinate system, stresses, projection, velocity, cylindrical coordinates, unsteady motion , asymmetric, viscous, compressible fluid, plastic pipe
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Serediuk, M. D. "MATHEMATICAL MODELING OF THE CHARACTERISTICS OF OIL PUMPS, TAKING INTO ACCOUNT THE VISCOSITY OF THE TRANSPORTED OIL." Oil and Gas Power Engineering, no. 1(31) (June 26, 2019): 54–64. http://dx.doi.org/10.31471/1993-9868-2019-1(31)-54-64.
Повний текст джерелаАнотація:
For solving a range of assignments concerning design and operation of main oil pipelines it is necessary to possess appropriate mathematical models of centrifugal pump characteristics as the pumps appear to be the main equipment of pumping stations. Known analytical dependences describe only operating envelope of the pumps and thus can`t be applied for low flowrate regimes being inherent to the Ukrainian oil transmission system. In addition, these mathematical models do not take into account the effect of the viscosity of the transported oil on the pressure and energy characteristics of oil pumps. The work features the improved the method of mathematical modeling of the hydrodynamic characteristics of centrifugal pumps of main oil pipelines for the full range of working feeds, taking into account the effect of the viscosity of the pumped oil. It is also given a consideration to mathematical models of oil pumps characteristics, coefficients of which are found by the coordinates of two or three points of corresponding charts, and polynomial models, the coefficients of which are determined by the least squares method by a set of passport or experimental data. Adequate mathematical models for pressure characteristics and efficiency coefficient of oil pumps are proposed that are suitable for creation of computational algorithms for determining the throughput and energy efficiency of operation of main oil pipelines. It has been proved that for oil pumps that are operated under different combining schemes with significant reduction of theirs operation flowrate the advantage should be given to the mathematical models of the characteristics obtained by the method of least squares. In this case, polynomial models of the third degree provide the necessary accuracy of the calculations. The method of introducing a control unit for the influence of the transported oil viscosity on the characteristics of the pumps is proposed under determining the capability and energy efficiency of operation of main oil pipelines
3
Bobkov, S. P., and A. S. Chernjavskaja. "Simulation of continuous flows with discrete models." Vestnik IGEU, no. 3 (2019): 68–75. http://dx.doi.org/10.17588/2072-2672.2019.3.068-075.
Повний текст джерелаАнотація:
The vast majority of heat and power processes include the motion of significant amounts of gases and liq-uids. This makes it important and quite urgent to develop approaches for computer simulation and visualiza-tion of continuum flows in technological devices and pipelines. A whole set of new approaches to mathematical modelling of continuum flows has been recently developed. The most common one is using discrete mathematical models for these purposes. Discrete approaches can simplify modeling procedures in cases where traditional methods require complex time-consuming calculations. At the same time, correct-ness of description of various flow regimes by the discrete methods is often questioned. The second problem of the mentioned models is a large-scale transition from model discrete parameters to generally accepted macroscopic characteristics of flows. The purpose of this work is to determine continuous flow regimes that can be correctly described by certain models. The paper considers discrete dynamic models in the form of lattice gases. A continuum in this case is represented by a set of particles moving only in allowed directions. Despite certain limitations, there is solid evidence that lattice gases quite successfully describe a whole range of hydrodynamic phenomena, and the obtained results do not contradict the generally accepted views on the physical nature of continuum motion processes. The paper describes approaches that allow estimating flow parameters using generally accepted macroscopic indicators. It also studies possible application areas of lattice gas models using the motion of virtual particles on a spatial lattice (HPP and FHP models) and the model based on the discrete analogue of the Boltzmann equation (LBM model) to simulate and visualize continuum flows. The obtained data are in good agreement with the generally accepted results and do not contradict the provisions of classical hydrodynamics. The paper shows that the models considering particle collisions (HPP and FHP) are applicable to describing gas flows in laminar regimes. The LBM model should be considered to be more correct for simulation and visualization of real fluid flows.
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Bondar, Denis V., Vladimir V. Zholobov та Oleg S. Nadezhkin. "Метод определения параметров утечек в трубопроводах на основе гидродинамических моделей". SCIENCE & TECHNOLOGIES OIL AND OIL PRODUCTS PIPELINE TRANSPORTATION, № 5 (9 грудня 2021): 515–27. http://dx.doi.org/10.28999/2541-9595-2021-11-5-515-527.
Повний текст джерелаАнотація:
It is known that on the basis of the pipeline non-stationary hydrodynamic model after identification of parameters included in it, it is possible to adequately reproduce the full-scale hydraulic characteristics of transported medium flow by resolving the primal problem of hydraulics, in particular, the primal problem of identifying leakage parameters. The numerical solution of the inverse problem, in contrast to the analytical solution, is usually reduced to a multiple solution of the primal problem. In the present work, the hydrodynamic mathematical model of a pipeline with two parameters that have been identified and fluid withdrawal in the set section is confined to differential equations of evolutionary type for medium cross-section pressure and mass flow. Based on the built partial analytical solutions of these equations, dependences have been obtained for calculation of pressure values in the oil pipeline operated in stationary mode with existing liquid withdrawal (leakage). Results of application of analytical solutions to the method of sensitivity functions in the inverse problem of identifying leakage parameters have been reviewed. Exact analytical solution (in implicit form) of the inverse problem has been obtained to make it possible to relate the location of the leak to readings of pressure sensors, to the pipeline and the transported fluid parameters. Известно, что на основе нестационарной гидродинамической модели трубопровода после идентификации входящих в нее параметров можно адекватно воспроизводить натурные гидравлические характеристики потока транспортируемой среды путем решения прямой задачи гидравлики, в частности, прямой задачи об утечке, когда местоположение и расход отбора заданы. Численное решение обратной задачи, в отличие от аналитического обычно сводится к многократному решению прямой задачи. В предлагаемой работе гидродинамическая математическая модель трубопровода с двумя параметрами, прошедшими идентификацию, и отбором жидкости в заданном сечении сведена к дифференциальным уравнениям эволюционного типа для среднего по сечению давления и массового расхода. На основе частных аналитических решений данных уравнений получены зависимости для определения давления в работающем в стационарном режиме нефтепроводе при наличии отбора (утечки). Рассмотрены результаты применения аналитических решений к методу функций чувствительности в обратной задаче утечки. Получено точное аналитическое решение (в неявной форме) обратной задачи, позволяющее связать местоположение утечки с показаниями датчиков давления, характеристиками трубопровода и транспортируемой среды.
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Жолобов, Владимир Васильевич, Валерий Юрьевич Морецкий, and Рустям Фаатович Талипов. "Distribution of volume of water accumulations in profile oil pipeline." SCIENCE & TECHNOLOGIES OIL AND OIL PRODUCTS PIPELINE TRANSPORTATION, no. 5 (October 31, 2022): 438–51. http://dx.doi.org/10.28999/2541-9595-2022-12-5-438-451.
Повний текст джерелаАнотація:
Введение. Имеющиеся математические модели поведения воды в эксплуатируемых нефтепроводах не учитывают возможность одновременного существования неподвижной и подвижной форм водных образований. Это ограничивает область применимости таких расчетных моделей и делает актуальной разработку обобщенных гидравлических моделей. Методы. Применение положений многоскоростного континуума позволяет сформулировать общую математическую модель многофазной среды, которая при адаптации допускает высокую степень детализации гидравлического описания накопления и миграции воды. При этом будут сформулированы незамкнутые уравнения (балансовые законы сохранения), которые применимы к описанию формирования условно неподвижного водного скопления и миграции коалесцированной воды как в непрерывной (ручейковой), так и в дисперсно-капельной форме на технологическом участке магистрального нефтепровода. Постановка задачи сводится к конкретизации межфазного взаимодействия на основе пограничного слоя и аналогии с движением влекомых наносов в теории русловых течений. Результаты. На основе соотношений пограничного слоя на поверхности контакта фаз и аналогового предположения о профиле продольной скорости получены расчетные зависимости для скорости среды на границе контакта, а также формулы для расчета силового взаимодействия и дисперсно-капельного массообмена. В отличие от имеющихся в научно-технической литературе вариантов замыкания здесь применен профиль скорости в циркуляционном течении воды. Обсуждение. Полученные зависимости в общем случае содержат дополнительные параметры, подлежащие идентификации и ранжированию по степени влияния на основные гидродинамические характеристики стратифицированных течений с поправкой на разницу в диаметрах срываемых и оседающих капель. Для этого требуются данные специально поставленных стендовых и численных экспериментов. Выводы. Представленная модель поведения воды в профильном трубопроводе сформулирована с учетом возможного волнового срыва капель с поверхности неподвижного водного скопления, полного дисперсно-капельного выноса или переноса капель на последующие участки. При практических расчетах, помимо обычной процедуры предварительной идентификации параметров однофазных моделей, дополнительно необходима идентификация параметров пограничного слоя на границе контакта фаз. Ключевые слова: стратифицированное течение, ручейковое течение, водные скопления в трубопроводах, двухфазное течение, математическая модель течения, дисперсная фаза, гидравлическая модель Introduction. The available mathematical models of water behavior in operated oil pipelines do not take into account the possibility of simultaneous existence of fixed and mobile forms of water formations. This limits the applicability of such design models and makes the development of generalized hydraulic models relevant. Methods. In the mechanics of multiphase media, on the basis of a multi-speed continuum, a mathematical apparatus is built, which, when adapted, allows any degree of detail in the hydraulic description of the process of accumulation and migration of water. At the same time, unclosed equations (balance conservation laws) are formulated, which are also applicable to the description of the formation of a conditionally stationary water accumulation and migration of coalesced water both in continuous (stream) and dispersed-droplet form in the technological section of the main oil pipeline. The formulation of the problem is reduced to the concretization of interphase interaction on the basis of the boundary layer and analogy with the movement of attracted sediments in the theory of channel currents. Results. Based on the ratios of the boundary layer on the phase contact surface and the assumption of the longitudinal velocity profile, calculated dependencies for the velocity of the medium at the contact boundary, as well as formulas for calculating the force interaction and disperse-droplet mass transfer, are obtained. In contrast to the options available in the literature, the velocity profile in the circulation flow of water is applied here. Discussion. The obtained dependencies in the general case contain additional parameters to be identified and ranked according to the degree of influence on the main hydrodynamic characteristics of the stratified currents, adjusted for the difference in the diameters of the torn and settling droplets. This requires data from specially staged bench and numerical experiments. Conclusion. The presented model of water behavior in the profile pipeline is formulated taking into account the possible wave breakage of droplets from the surface of a stationary water accumulation, complete dispersion-droplet removal or transfer of droplets to subsequent areas. In practical calculations, in addition to the usual procedure for preliminary identification of the parameters of single-phase models, it is additionally necessary to identify the parameters of the boundary layer at the phase contact boundary.
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Bogdevičius, Marijonas, Jolanta Janutėnienė, Rimantas Didžiokas, Saulius Razmas, Viktor Skrickij, and Paulius Bogdevičius. "Investigation of the hydrodynamic processes of a centrifugal pump in a geothermal system." Transport 33, no. 1 (March 29, 2016): 223–30. http://dx.doi.org/10.3846/16484142.2016.1155079.
Повний текст джерелаАнотація:
The hydrodynamic and thermodynamic processes of geothermal well extraction are investigated and presented in this paper. The paper presents mathematical models for a multi-level centrifugal pump and pipeline system. The mathematical models were used to evaluate gas (nitrogen) emission in water and its effects on hydrodynamic processes. Experimental studies and mathematical modelling showed that the gas content of the fluid increases the pressure and flow pulsations within a centrifugal pump. The variation in the height of the liquid column in extraction has an influence on characteristics of the multistage centrifugal pump used in wells.
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Paryshev, Emil V. "Approximate mathematical models in high-speed hydrodynamics." Journal of Engineering Mathematics 55, no. 1-4 (July 26, 2006): 41–64. http://dx.doi.org/10.1007/s10665-005-9026-x.
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Osiadacz, Andrzej J., and Marta Gburzyńska. "Selected Mathematical Models Describing Flow in Gas Pipelines." Energies 15, no. 2 (January 10, 2022): 478. http://dx.doi.org/10.3390/en15020478.
Повний текст джерелаАнотація:
The main aim of simulation programs is to study the behavior of gas pipe networks in certain conditions. Solving a specified set of differential equations describing transient (unsteady) flow in a gas pipeline for the adopted parameters of load and supply will help us find out the value of pressure or flow rate at selected points or along selected sections of the network. Transient gas flow may be described by a set of simple or partial differential equations classified as hyperbolic or parabolic. Derivation of the mathematical model of transient gas flow involves certain simplifications, of which one-dimensional flow is most important. It is very important to determine the conditions of pipeline/transmission network operation in which the hyperbolic model and the parabolic model, respectively, should be used. Parabolic models can be solved numerically in a much simpler way and can be used to design simulation programs which allow us to calculate the network of any structure and any number of non-pipe elements. In some conditions, however, they describe the changes occurring in the network less accurately than hyperbolic models do. The need for analysis, control, and optimization of gas flows in high-pressure gas pipelines with complex structure increases significantly. Very often, the time allowed for analysis and making operational decisions is limited. Therefore, efficient models of unsteady gas flows and high-speed algorithms are essential.
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Saifutdinov, A. I., and G. E. Korobkov. "ROBUST MATHEMATICAL MODELS FOR DURABILITY ESTIMATION OF UNDERWATER OIL PIPELINES." Problems of Gathering, Treatment and Transportation of Oil and Oil Products, no. 4 (June 2018): 67. http://dx.doi.org/10.17122/ntj-oil-2018-4-67-72.
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Sukhinov, A., A. Chistyakov, S. Protsenko, and E. Protsenko. "Study of 3D discrete hydrodynamics models using cell filling." E3S Web of Conferences 224 (2020): 02016. http://dx.doi.org/10.1051/e3sconf/202022402016.
Повний текст джерелаАнотація:
Modern methods and tools for coastal hydrodynamics modeling indicate the necessity of constructing discrete analogs of models for ones the properties: balance and conservation laws (for mass, flows, impulse), stability, convergence and etc. have been fulfilled. The paper considers a continuous three-dimensional mathematical model of the hydrodynamics of water basins and its discretization. The pressure correction method at variable water medium density was used to solve the problem of hydrodynamics. The considered discrete mathematical models of hydrodynamics take into account the filling of control cells on rectangular grids. This increased the accuracy of the solution in the case of complex geometry by improving the boundary approximation. From the obtained estimates of the components of the velocity vector, it follows that there are no two or more stationary regimes in which all forces are balanced, and the solution to the discrete problem exists and is unique and tends to the solution of the continuous problem upon reaching the stationary regime. Also the balance of the flows for the discrete model has been proved as well as absence of non-conservative dissipative terms.
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Cuamatzi-Meléndez, Ruben, MA Hernandez Rojo, AO Vázquez-Hernández, and Francisco L. Silva-González. "Predicting erosion in wet gas pipelines/elbows by mathematical formulations and computational fluid dynamics modeling." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, no. 10 (December 4, 2017): 1240–60. http://dx.doi.org/10.1177/1350650117745418.
Повний текст джерелаАнотація:
Sand erosion has been identified as a potential damage and failure mechanism in pipelines/elbows employed to transport gas from wells to terminals. Erosion can cause localized material loss decreasing the structural integrity of pipelines/elbows leading to failure. As a result, sand erosion has been the object of much research work in the oil and gas industry. The prediction of erosion caused by sand transported by hydrocarbons flow is a difficult task due to the large number of variables involved. At present, a great number of empirical models have been developed to predict sand erosion in smaller diameter pipelines under laboratory conditions. Therefore, such formulations generally present uncertainties for their application in larger diameter pipelines employed to transport oil and gas because there is no fundamental basis showing how the empirical formulations can be extrapolated to large diameters pipelines as most of the models have been developed on the basis of elementary laboratory experiments, which may not represent the real sand erosion conditions. Furthermore, most of the analytical/empirical models were developed for specific pipeline/elbows diameters and cannot be employed to predict erosion in different engineering structures. Hence, in the present work a computational fluid dynamic modeling strategy is proposed, which incorporated fundamental physically erosion parameters to predict erosion in larger diameter pipelines/elbows. The methodology was applied to different elbows/pipelines diameters in order to investigate how pipeline's diameter, sand production rate, and sand particles sizes affect the erosion mechanism and the erosion rate. The results showed the importance of including fluid and flow conditions, sand particles trajectory, and self-particles movement. The computational fluid dynaimcs results were compared with those obtained with the most employed empirical models to predict sand erosion in the oil and gas industry models published in the literature, and it was shown that the proposed modeling strategy can be used to predict erosion in larger diameters pipelines/elbows with good results.
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Kang, Qi, Jiapeng Gu, Xueyu Qi, Ting Wu, Shengjie Wang, Sihang Chen, Wei Wang, and Jing Gong. "Hydrodynamic Modeling of Oil–Water Stratified Smooth Two-Phase Turbulent Flow in Horizontal Circular Pipes." Energies 14, no. 16 (August 23, 2021): 5201. http://dx.doi.org/10.3390/en14165201.
Повний текст джерелаАнотація:
In the petrochemical industry, multiphase flow, including oil–water two-phase stratified laminar flow, is more common and can be easily obtained through mathematical analysis. However, there is limited mathematical analytical model for the simulation of oil–water flow under turbulent flow. This paper introduces a two-dimensional (2D) numerical simulation method to investigate the pressure gradient, flow field, and oil–water interface height of a pipeline cross-section of horizontal tube in an oil–water stratified smooth flow. Three Reynolds average N–S equation models (k−ε, k−ω, SST k−ω) are involved to simulate oil–water stratified smooth flow according to the finite volume method. The pressure gradient and oil–water interface height can be computed according to the given volume flow rate using the iteration method. The predicted result of oil–water interface height and velocity profile by the model fit well with several published experimental data, except that there is a large error in pressure gradient. The SST k−ω turbulence model appears higher accuracy for simulating oil–water two-phase stratified flow in a horizontal pipe.
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Maiolo, Mario, Manuela Carini, Gilda Capano, Daniela Pantusa, and Marco Iusi. "Trends in metering potable water." Water Practice and Technology 14, no. 1 (December 10, 2018): 1–9. http://dx.doi.org/10.2166/wpt.2018.120.
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Abstract Sustainable management of drinking water distribution systems requires information on the operating status of system components to identify the best operational management measures. The ability to acquire information on tank levels, pipeline flow and real-time pressure offers an efficient and cost-effective management perspective, and enables wider monitoring, which can improve (physical) security as well. The technology of measuring instruments for hydrodynamic variables, used to monitor potable water systems, differs in their independence from electronic data acquisition components and ability to connect to remote data communication systems. Advanced water measurement infrastructure is characterized by the ability to capture data with measurable errors from anywhere in the system, without restrictions on communication type. This paper deals with the measurement of hydrodynamic parameters and a proposal for water meter classification. It includes analysis of the main water meter and data tele-acquisition infrastructure. Several selection criteria are evaluated with respect to their ability to support mathematical hydraulic models and expert systems for water distribution system management.
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Kurbatova G. I., Klemeshev V. A., and Egorov N. V. "Estimation of possibilities of calculations based on simplified models of the leak location in gas pipelines." Technical Physics 92, no. 10 (2022): 1309. http://dx.doi.org/10.21883/tp.2022.10.54357.119-22.
Повний текст джерелаАнотація:
For gas transportation through pipes in normal and emergency modes, a comparison of calculations based on mathematical models of various degrees of generality is presented. A mathematical model of a non-isothermal steady flow of a mixture of gases and its simplified versions are studied. For simplified options, simple analytical dependencies were obtained for calculating flow characteristics and calculating the location of an emergency gas leak. Examples of calculations of pressure distributions, temperature and leakage coordinates in gas pipelines of medium pressures according to the general and simplified models are provided. The examples cover the parameter change area of practical interest. The conditions for the admissibility of using simplified models for calculating the coordinates of a leak of medium intensity and different locations are determined. Keywords: gas pipelines, adequacy of the model, simplifications, calculation of the place of emergency leakage, compressibility factor.
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Al-Isawi, J. K. T. "Computational Experiments for One Class of Mathematical Models in Thermodynamics and Hydrodynamics." Journal of Computational and Engineering Mathematics 4, no. 1 (2017): 16–26. http://dx.doi.org/10.14529/jcem170102.
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Korobkin, Alexander, Emilian I. Părău, and Jean-Marc Vanden-Broeck. "The mathematical challenges and modelling of hydroelasticity." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1947 (July 28, 2011): 2803–12. http://dx.doi.org/10.1098/rsta.2011.0116.
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Hydroelasticity brings together hydrodynamics and elastic theories. It is concerned with deformations of elastic bodies responding to hydrodynamic excitations, which themselves depend on elastic deformation. This Theme Issue is intended to identify and to outline mathematical problems of modern hydroelasticity and to review recent developments in this area, including physically and mathematically elaborated models and the techniques used in their analysis.
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Yurchenko, Elena, Konstantin Makarov, Astkhik Kakosian, and Eric Biryukbaev. "Physical modeling of pipeline resonance in civil buildings." E3S Web of Conferences 135 (2019): 01010. http://dx.doi.org/10.1051/e3sconf/201913501010.
Повний текст джерелаАнотація:
The method of experimental determination of the magnitudes of pipelines resonant vibrations on small-sized physical models of 1:10 of actual size is shown. The measured values of the oscillation frequencies of pipe models with hinged and pinched supports on both sides are compared with their mathematical counterparts. Fluctuations of pipes with clogging allow us to determine its effect on the values of the resonant frequencies. The obtained results are essential for predicting accidents and fatigue failures of pipelines for various purposes. During the tests on steel models, the excited harmonic sound oscillations of the models are captured by an electromagnetic transducer and transmitted through a microphone amplifier to a computer that serves as an oscilloscope.
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Pomraning, G. C., and R. H. Szilard. "Flux-limited diffusion models in radiation hydrodynamics." Transport Theory and Statistical Physics 22, no. 2-3 (April 1993): 187–220. http://dx.doi.org/10.1080/00411459308203812.
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Korniyenko, Bogdan, and Andrii Nesteruk. "Mathematical modelling of granulation process in fluidised bed (overview of models)." Proceedings of the NTUU “Igor Sikorsky KPI”. Series: Chemical engineering, ecology and resource saving, no. 2 (June 30, 2022): 51–59. http://dx.doi.org/10.20535/2617-9741.2.2022.260349.
Повний текст джерелаАнотація:
One of the most common methods of making mineral fertilizers is granulation. Fertilizers in the form of granules have a number of advantages over conventional fertilizers in the form of powder or liquid, namely, ease of transportation, well absorbed and less susceptible to weathering from the soil, convenient to use. To obtain solid particles from liquid starting material such as solutions, emulsions or suspensions, the following processes are used: crystallization, granulation, spray drying. Depending on the focus of the study, the fluidized bed granulation process can be modeled at different levels of abstraction. The dynamics of individual particles is modeled on a microscopic scale. The interaction of a particle with a liquid, equipment or other particles is considered. The next rougher level of abstraction is the mesoscale. Here the particles are divided into classes according to their characteristics. It is assumed that the particles of the class have the same properties and dynamics. On a macroscopic scale, the roughest level of approximation, attention is focused on the integral behavior of the whole set of particles. As a result, the selected characteristic values describe the state of the particle layer. There are different approaches to modeling for each scale. It is proposed to describe the microscopic scale using the hydrodynamics model, the mesoscale using the balance model, and the macroscopic scale using the moments method or the Lagrange-Euler model. A combined balance-hydrodynamics model and a multi-chamber balance model that can be used for the tasks of building information technology for fluidized bed granulation process control technology are also considered.
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Niu, X. D., C. Shu, Y. T. Chew, and T. G. Wang. "Investigation of Stability and Hydrodynamics of Different Lattice Boltzmann Models." Journal of Statistical Physics 117, no. 3-4 (November 2004): 665–80. http://dx.doi.org/10.1007/s10955-004-2264-x.
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Slipchuk, Andrii, Petro Pukach, and Myroslava Vovk. "Asymptotic Study of Longitudinal Velocity Influence and Nonlinear Elastic Characteristics of the Oscillating Moving Beam." Mathematics 11, no. 2 (January 7, 2023): 322. http://dx.doi.org/10.3390/math11020322.
Повний текст джерелаАнотація:
Mathematical models of the nonlinear transversal oscillations for a beam moving along its axis have been studied. These models deal with the nonlinearity of body elastic properties and with the influence of physical–mechanical and kinematic parameters on the oscillation amplitude and frequency of the moving one-dimensional nonlinear systems as well. A procedure for studying both cases, non-resonance and resonance oscillation regimes, has been developed. The paper focuses on the influence of the longitudinal velocity, nonlinear elastic material properties, and external periodical perturbations on the dynamical process of beam transversal oscillation. The obtained mathematical model could be applied to describe the oscillation behavior of the different types of pipelines (liquid or gas). The proposed results allow the estimation of the influence of these parameters on the amplitude and frequency of the oscillations. Mathematical analysis realized by asymptotic methods enables the prediction of the resonance phenomena and proposal of a numerical algorithm to plan the most effective operation regime. Applications of this approach in engineering, particularly to construct the corresponding elements of industrial environments and pipelines, are also discussed.
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Bogdevicius, Marijonas, Jolanta Janutėnienė, and Oleg Vladimirov. "Simulation of Hydrodynamics Processes of Hydraulic Braking System of Vehicle." Solid State Phenomena 147-149 (January 2009): 296–301. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.296.
Повний текст джерелаАнотація:
The 3D vehicle with the hydraulic braking system and disc brake with the wheel has been investigated. The dynamic models of the disk brake assembly and the wheel have been constructed. The automobile hydraulic braking system consisting of two contours is considered. . The mathematical model of the hydraulic braking system is presented, where the flow of liquid and the interaction of liquid with the rigid bodies are taken into account. The flow of fluid in a hydraulic system is described by a system of equations of a hyperbolic type, which is solved by a characteristics method. During the mathematical simulations and natural experimentations the following results were achieved. The systems of equations of dynamic models’ motions are solved by numerical methods. The dynamic characteristics of the braking system of the automobile are obtained. The results of extreme braking tests and calculations are presented.
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Harper, S. R., and M. T. Suidan. "Anaerobic Treatment Kinetics: Discussers' Report." Water Science and Technology 24, no. 8 (October 1, 1991): 61–78. http://dx.doi.org/10.2166/wst.1991.0218.
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A discussion of principles guiding the experimental elucidation of microbial growth and substrate utilization kinetics, and the development of mathematical models for anaerobic wastewater treatment systems, is presented. Recent developments in the areas of anaerobic treatment microbiology (including biomass characterization), biochemical mechanisms, microbial growth dyamics, reactor hydrodynamics, and mathematical modeling approaches are presented and explored.
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Chekurin, Vasyl, and Olga Khymko. "Mathematical models for leak identification in long-distance gas pipeline. Stationary operational mode." Physico-mathematical modelling and informational technologies, no. 25 (May 25, 2017): 157–69. http://dx.doi.org/10.15407/fmmit2017.25.157.
Повний текст джерелаАнотація:
Direct and inverse problems for leak identification in long distance gas pipelines in stationary operational modes on the base of data obtained by pressure monitoring in pipeline’s inlet, outlet and in several intermediate check points have been formulated. Algorithms for solving of the formulated problems have been developed and their numerical study has been done. On this basis methods for leak detecting, its intensity and location determination with the use of the data of pressure monitoring have been suggested. Quantitative evaluation of precisions of the proposed methods has been conducted.
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Eremin, Anton, Konstantin Trubitsyn, Sergey Kolesnikov, Igor Kudinov, and Vasily Tkachev. "Computer models of hydraulic systems of district heating." MATEC Web of Conferences 193 (2018): 02028. http://dx.doi.org/10.1051/matecconf/201819302028.
Повний текст джерелаАнотація:
A mathematical and computer model of a district heating network fed by two heat sources located at significantly different elevation marks has been developed. The model is based on the electrohydraulic analogy of electric current spread in conductors and liquid pressure spread in pipelines, which are described by the same equations. In particular, the first and second Kirchhoff’s laws used in the calculation of electrical networks are applied to calculate the velocities and pressures in a complex multi-ring pipeline system. In order to maximize the approximation of the computer model to the real hydraulic network (in resistance to the process of heating agent flow), the method of automatic identification of the model is applied. This method is an iterative process of changing the hydraulic resistances in pipelines of the model in such a way that the results obtained from the calculations would have the least differences from the experimental data. The accuracy of identification depending on the number of points with known experimental data is 3 – 5%.
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Lukovich, V. V. "Mathematical models for calculation of the electrochemical protection parameters of pipelines from electrochemical measurements." Powder Metallurgy and Metal Ceramics 34, no. 7-8 (1996): 446–52. http://dx.doi.org/10.1007/bf00559438.
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Bondarenko, V. I., V. V. Bilousov, F. V. Nedopekin, and J. I. Shalapko. "The Mathematical Model of Hydrodynamics and Heat and Mass Transfer at Formation of Steel Ingots and Castings." Archives of Foundry Engineering 15, no. 1 (March 1, 2015): 13–16. http://dx.doi.org/10.1515/afe-2015-0003.
Повний текст джерелаАнотація:
Abstract The generic mathematical model and computational algorithm considering hydrodynamics, heat and mass transfer processes during casting and forming steel ingots and castings are offered. Usage domains for turbulent, convective and non-convective models are determined depending on ingot geometry and thermal overheating of the poured melt. The expert system is developed, enabling to choose a mathematical model depending on the physical statement of a problem.
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Kitaytseva, Elena. "A new approach to hydraulic calculations of free-flow drainage systems." MATEC Web of Conferences 144 (2018): 01018. http://dx.doi.org/10.1051/matecconf/201814401018.
Повний текст джерелаАнотація:
The accuracy of hydraulic calculations is determined by the accuracy of the mathematical models inherent in their foundation. The results of calculations, obtained by different models, and differing from each other by 5-10% is considered identical. The present study examines classical ways of finding the Chezy formula that are used for calculations of free-flow pipelines. These formulas differ from each other not only in parameters but also in the form of the functional dependence. The equation, underlying the hydraulic calculations, is nonlinear. Its solution is possible only in the number of well-established methods. It offers numerical computing to find pipelines diameters and their filling, as well as the algorithm to realize it. It conducts numerical experiment to compare pipelines diameters and filling and flow velocities. It presents frequency characteristics to distribute the parameters under analysis. For a specific example, the difference of cost of pipes, the diameters of which was found using the various formulas for coefficient Chezy, was calculated.
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Pyanylo, Ya, M. Prytula, N. Prytula, and N. Lopuh. "Models of mass transfer in gas transmission systems." Mathematical Modeling and Computing 1, no. 1 (2014): 84–96. http://dx.doi.org/10.23939/mmc2014.01.084.
Повний текст джерелаАнотація:
The models of gas movement in pipelines and gas filtration processes in complex porous media are considered in entire and fractional derivatives. The method for linearization of equations, which are included in the mathematical model of mass transfer, is suggested as well as an iterative scheme for solving initial systems of nonlinear differential equations is constructed. The finite-element model of the problem with the use of the Petrov-Galerkin method and Grunwald-Letnikov scheme concerning derivatives of the fractional order are implemented. The research of the models is carried out as well as comparative analysis of the numerical results is done.
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Holdych, D. J., D. Rovas, J. G. Georgiadis, and R. O. Buckius. "An Improved Hydrodynamics Formulation for Multiphase Flow Lattice-Boltzmann Models." International Journal of Modern Physics C 09, no. 08 (December 1998): 1393–404. http://dx.doi.org/10.1142/s0129183198001266.
Повний текст джерелаАнотація:
Lattice-Boltzmann (LB) models provide a systematic formulation of effective-field computational approaches to the calculation of multiphase flow by replacing the mathematical surface of separation between the vapor and liquid with a thin transition region, across which all magnitudes change continuously. Many existing multiphase models of this sort do not satisfy the rigorous hydrodynamic constitutive laws. Here, we extend the two-dimensional, seven-speed Swift et al. LB model1 to rectangular grids (nine speeds) by using symbolic manipulation (MathematicaTM) and compare the LB model predictions with benchmark problems, in order to evaluate its merits. Particular emphasis is placed on the stress tensor formulation. Comparison with the two-phase analogue of the Couette flow and with a flow involving shear and advection of a droplet surrounded by its vapor reveals that additional terms have to be introduced in the definition of the stress tensor in order to satisfy the Navier–Stokes equation in regions of high density gradients. The use of Mathematica obviates many of the difficulties with the calculations "by-hand," allowing at the same time more flexibility to the computational analyst to experiment with geometrical and physical parameters of the formulation.
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Mazurov, Mikhail. "Nonlinear Concave Spiral Waves in Active Media Transferring Energy." EPJ Web of Conferences 224 (2019): 02011. http://dx.doi.org/10.1051/epjconf/201922402011.
Повний текст джерелаАнотація:
Spiral concave autowaves are widely implemented in physics, chemistry, hydrodynamics, meteorology and other fields. A mathematical model of spiral concave autowaves based on the Fitzhugh-Nagumo equation and modified axiomatic models are presented. The existence of spiral concave autowaves transferring energy was predicted via computational experiments. Applications of spiral concave autowaves carrying energy in hydrodynamics, generation of tornadoes, breaking waves, and tsunamis and examples of such autowaves in biology and medicine are reviewed and the importance of concave spiral autowaves transferring energy is emphasized.
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Aguirre-Mendoza, Andres M., Sebastián Oyuela, Héctor G. Espinoza-Román, Oscar E. Coronado-Hernández, Vicente S. Fuertes-Miquel, and Duban A. Paternina-Verona. "2D CFD Modeling of Rapid Water Filling with Air Valves Using OpenFOAM." Water 13, no. 21 (November 4, 2021): 3104. http://dx.doi.org/10.3390/w13213104.
Повний текст джерелаАнотація:
The rapid filling process in pressurized pipelines has been extensively studied using mathematical models. On the other hand, the application of computational fluid dynamics models has emerged during the last decade, which considers the development of CFD models that simulate the filling of pipes with entrapped air, and without air expulsion. Currently, studies of CFD models representing rapid filling in pipes with entrapped air and with air expulsion are scarce in the literature. In this paper, a two-dimensional model is developed using OpenFOAM software to evaluate the hydraulic performance of the rapid filling process in a hydraulic installation with an air valve, considering different air pocket sizes and pressure impulsion by means of a hydro-pneumatic tank. The two-dimensional CFD model captures the pressure evolution in the air pocket very well with respect to experimental and mathematical model results, and produces improved results with respect to existing mathematical models.
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Khurramova, Rano, Bahrom Yuldashev, and Lutfullo Kuldashev. "MODELS AND ALGORITHMS OF THE DYNAMICS OF THE INFLUENCE OF GAS DYNAMIC CALCULATIONS OF A SINGLE-STRAIN GAS PIPELINE WITH A CONSTANT DIAMETER." TECHNICAL SCIENCES 5, no. 3 (May 30, 2020): 16–25. http://dx.doi.org/10.26739/2181-9696-2020-5-3.
Повний текст джерелаАнотація:
The complexity of the analytical representation of the processes occurring in individual technological objects, in particular in gas pipelines, taking into account various technological limitations, is characterized by the absence of general mathematical descriptions of the operating modes in real time, which determines the relevance of the work.
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Frimpong, Samuel, Oluropo Rufus Ayodele, and Jozef Szymanski. "Oil Sands Slurry Flow in Flexible Pipe." Journal of Fluids Engineering 126, no. 1 (January 1, 2004): 133–38. http://dx.doi.org/10.1115/1.1637929.
Повний текст джерелаАнотація:
Production cost and efficiency optimization for the Athabasca oil sands is a key to securing North America’s energy supply. Current oil sands production cost is about $13/bbl compared with $1.25/bbl for conventional crude oil. The effort to reduce production cost must focus on truck haulage because it contributes the dominant component of the production cost of about 26%. Toward this objective, hydraulic transportation has become a competitive means for materials handling. There is a desire to extend the hydraulic transport system to production faces using mobile train of flexible pipelines to optimize the system efficiency and cost. This flexible arrangement introduces a unique set of hydraulic transport problems, which must be addressed through rigorous modeling and analysis. This paper provides multiphase oil sand slurry models in flexible pipelines. New mathematical models are developed to characterize the multi-phase flow of oil sands slurry. The models combine the effects of dispersed particles and the carrier continuous phases. The coupled equations of each field are solved numerically for flexible pipe configuration. The models yield the productivity and deliverability of bitumen slurry between two mine facilities. The flexible arrangement allows modeling in elbow-type joint at different angles and in conventional linear pipelines, enabling adaptation of pipelines to various mine outlays. Numerical examples are presented to show the applicability of the new model and to ascertain optimum operational conditions of the flexible pipes in mine layouts.
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Гольдман, Н. Л. "Study of some mathematical models for nonstationary filtration processes." Numerical Methods and Programming (Vychislitel'nye Metody i Programmirovanie), no. 1 (January 13, 2020): 1–12. http://dx.doi.org/10.26089/nummet.v21r101.
Повний текст джерелаАнотація:
Рассматриваются математические модели, связанные с изучением нестационарных процессов фильтрации в подземной гидродинамике. Они представляют собой нелинейные задачи для параболических уравнений с неизвестной функцией источника в правой части. Одна из постановок является системой, которая состоит из краевой задачи с граничными условиями первого рода и из уравнения, задающего закон изменения по времени искомой функции источника. В другой постановке соответствующая система включает в себя краевую задачу с граничными условиями второго рода. Указанные постановки существенно отличаются от обычных краевых задач для параболических уравнений. Цель исследования - установить для этих нелинейных параболических задач условия однозначной разрешимости в классе гладких функций на основе априорных оценок метода Ротэ. We consider some mathematical models connected with the study of nonstationary filtration processes in underground hydrodynamics. These models involve nonlinear problems for parabolic equations with unknown source functions. One of the problems is a system consisting of a boundary value problem of the first kind and an equation describing a time dependence of the sought source function. In the other problem, the corresponding system is distinguished from the first one by boundary conditions of the second kind. These problems essentially differ from usual boundary value problems for parabolic equations. The aim of our study is to establish conditions of unique solvability in a class of smooth functions for the considered nonlinear parabolic problems. The proposed approach involves the proof of a priori estimates for the Rothe method.
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Sukhinov, A. I., A. E. Chistyakov, S. V. Protsenko, and E. A. Protsenko. "Vertical turbulent exchange structure and parametrization for 3D shallow water hydrodynamics models." Journal of Physics: Conference Series 2131, no. 2 (December 1, 2021): 022017. http://dx.doi.org/10.1088/1742-6596/2131/2/022017.
Повний текст джерелаАнотація:
Abstract The work describes research of vertical turbulent exchange structure and parametrization for 3D shallow water hydrodynamics models. In this paper, the coefficients of horizontal turbulent exchange are calculated using a whole set of averaging periods of turbulent velocity pulsations. Using experimental data on the pulsations of the velocity components, the coefficient of vertical turbulent exchange was calculated on the basis of various approaches to its parameterization, based on the analysis of the obtained coefficient distributions, the most adequate parameterization of the coefficient was selected, which is used in the software package. The distribution of the vertical turbulent exchange coefficient obtained in a numerical experiment was compared with the results of full-scale measurements, and the calculation results obtained using the mathematical statistics apparatus were analysed.
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Eyink, Gregory, Joel L. Lebowitz, and Herbert Spohn. "Hydrodynamics of stationary non-equilibrium states for some stochastic lattice gas models." Communications in Mathematical Physics 132, no. 1 (August 1990): 253–83. http://dx.doi.org/10.1007/bf02278011.
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Khvostov, A. A., A. A. Zhuravlev, E. A. Shipilova, R. S. Sumina, G. O. Magomedov, and I. A. Khaustov. "Simulink models of technological systems with perfect mixing and plug-flow hydrodynamics." Proceedings of the Voronezh State University of Engineering Technologies 81, no. 3 (December 20, 2019): 28–38. http://dx.doi.org/10.20914/2310-1202-2019-3-28-38.
Повний текст джерелаАнотація:
The dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics are based on the systems of algebraic and differential equations that describe a change in the basic technological parameters. The main difficulty in using such models in MathWorks Simulink™ computer simulation systems is the representation of ordinary differential equations (ODE) and partial differential equations (PDE) that describe the dynamics of a process as a MathWorks Simulink™ block set. The study was aimed at developing an approach to the synthesis of matrix dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics that allows for transition from PDE to an ODE system on the basis of matrix representation of discretization of coordinate derivatives. The process of synthesis of the dynamic matrix mathematical model was considered by the example of a sugar syrup cooler, the quality indicator of the finished product are selected as sucrose crystals and their portion in the total volume of caramel mass. Taking into account the dependence of syrup viscosity on temperature, thermal effects as a result of the process of crystallization of sucrose from syrup, design features of a typical caramel machine made it possible to clarify the dynamics of the process of syrup cooling. The model developed with this approach allows to obtain real-time estimates of temperatures at the outlet of the cooler, which makes it possible to study the dynamics of the technological process and synthesize the control system. The presented approach allows to implement mathematical models of ideal reactors in Simulink system and to move to matrix ordinary differential equations, which makes it possible to convert them into Simulink blocks. The approach is also applicable to other models of ideal reactors, which allows to form libraries of typical ideal reactors of Simulink system for synthesis of heat and mass exchange equipment. The proposed approach significantly simplifies the study and modernization of the current and the development of new technological equipment, as well as the synthesis of algorithms for controlling the processes therein.
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Курбатова, Г. И., В. А. Клемешев та Н. В. Егоров. "О возможности использования упрощенных моделей для определения места утечки в газопроводе". Журнал технической физики 92, № 10 (2022): 1509. http://dx.doi.org/10.21883/jtf.2022.10.53243.119-22.
Повний текст джерелаАнотація:
For gas transportation through pipes in normal and emergency modes, a comparison of calculations based on mathematical models of various degrees of generality is presented. A mathematical model of a non-isothermal steady flow of a mixture of gases and its simplified versions are studied. For simplified options, simple analytical dependencies were obtained for calculating flow characteristics and calculating the location of an emergency gas leak. Examples of calculations of pressure distributions, temperature and leakage coordinates in gas pipelines of medium pressures according to the general and simplified models are provided. The examples cover the parameter change area of practical interest. The conditions for the admissibility of using simplified models for calculating the coordinates of a leak of medium intensity and different locations are determined.
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Gurbanov, Abdulaga, Ijabika Sardarova, and Javida Damirova. "Building a mathematical model to prevent hydrate formation in gas pipelines." EUREKA: Physics and Engineering, no. 5 (September 30, 2022): 12–20. http://dx.doi.org/10.21303/2461-4262.2022.002541.
Повний текст джерелаАнотація:
Development of mathematical models of laminar gas flow in certainty and uncertainty conditions were considered. All factors that influence to character of flow of gas in pipeline and conditions of arising of hydrate inside of pipeline wall are analyzed. Results of analyze were used for development mathematical model of gas flow in pipeline that allow to calculate main parameters of hydrate deposition process. Model of gas flow consist of three non-linear differential equations that can be solved by exist soft wares. Two and three-dimension characteristic obtained, that describe of quantity of hydrate deposited at given process depending on time.
Besides, the effectiveness of using DELPHI 7 software to determine the preparation of gas for transportation and the hydrates formed during transportation and its prevention based on the results of the application software was discussed. As a result, the change in cross-sectional area of the pipeline of hydrates formed on the inner surface of the pipeline is shown in 3D. Hydrate formation and elimination are visually represented by graphs. The results of theoretical and practical studies of changes in the inner surface of the pipeline depending on temperature and pressure have been identified. All this was investigated during quasi-stationary gas flow in the pipelines and the results were obtained.
The assumes regarding calculation of parameters of gas flow were determined and necessary recommendations for applying of developed model in different conditions with taking account of temperature and pressure variation and depending on time of hydrate deposition were presented. The diagram of gas-hydrate separation boundary considered for detailed analysis of process
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Nadolin, Konstantin Arkadevich. "Simplified three-dimensional mathematical models of hydrodynamics and passive mass transfer in calm channel flows." Итоги науки и техники Серия «Современная математика и ее приложения Тематические обзоры» 196 (2021): 66–89. http://dx.doi.org/10.36535/0233-6723-2021-196-66-89.
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Oliinyk, A. P., G. V. Grigorchuk, and R. M. Govdyak. "THE MATHEMATICAL MODELLING METHODS APPLYING TO ESTIMATE THE PIPELINES TECHNICAL STATE AND ENVIRONMENT SITUATION." METHODS AND DEVICES OF QUALITY CONTROL, no. 1(42) (June 27, 2019): 97–103. http://dx.doi.org/10.31471/1993-9981-2019-1(42)-97-103.
Повний текст джерелаАнотація:
In the context of providing trouble-free operation of oil and gas pipelines and preventing possible negative impacts on the environment, the issues of constructing an integrated mathematical model for assessing the technical condition of pipelines and the impact of emergency situations on the state of the environment in the course of hydrocarbon leakage are considered. The model of the evaluation of the stress-strain state of the pipeline according to the data on the displacement of surface points for the above ground and underground sections is given by constructing the law of motion of the site by known displacements of a certain set of surface points using assumptions about the type of deformation of the sections and reproduction of the deformations and stresses tensors components on the basis of different models of deformed solid body.
The specified model does not require information on the whole complex of forces and loads acting on the investigated object during operation. The flow model has been refined in a pipeline with a violation of its tightness by recording a special type of boundary conditions for a Navier-Stokes equation system in a two-dimensional formulation and developing an original method for its solution on the basis of the finite difference method. In the article the stability conditions of the proposed numerical schemes on basis of the spectral sign of stability are presented. In order to assess possible negative impacts on the environment, a model of propagation of matter at its leakage from the pipeline was developed by solving two-dimensional diffusion equations taking into account the variables and different types of boundary conditions that take into account the number of sources of pollution and their intensity. The results of computations based on computational algorithms implemented by these models and graphic material illustrating these calculations are presented, peculiarities of distribution of harmful substances in the environment near the pipeline are analyzed. Directions of further researches for successful practical realization of the offered models are established.
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Rahimi-Ahar, Zohreh, and Mohammad Sadegh Hatamipour. "Hydrodynamics, numerical study and application of spouted bed." Reviews in Chemical Engineering 34, no. 6 (November 27, 2018): 743–66. http://dx.doi.org/10.1515/revce-2017-0036.
Повний текст джерелаАнотація:
Abstract This article reviews the major research and development on spouted beds (SBs). Due to its unique structural and flow characteristics, the SB is a very successful system in most applications. Two-phase and sometimes three-phase interactions generate a large number of variables to be noted in each process. Up-to-date information on the fundamentals and applications of SBs has been briefly presented, based on the published works. Thousands of interesting studies on hydrodynamic characteristics, numerical simulations, and new applications of SBs are reported. In the first step, the present work presents a review of hydrodynamic characteristics (circulation of solids in SB, measurement techniques for particle tracking and empirical hydrodynamics, pressure drop, maximum spoutable height, minimum spouting velocity, and diameter of the spout). In the second step, main mathematical models and computational fluid dynamics (CFD) simulation of the SB to predict and analyze different processes are described. Some main mathematical modeling and the recent advances of two fluid methods and discrete element method approaches in CFD simulation of SBs are summarized. In the last step, some new applications of the SB are presented. As the result of this review, we can observe the importance of further development of hydrodynamics structure, working on modeling and related correlations and improve the applications of SBs.
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Panasenko, Natalia, Nikolay Motuz, and Asya Atayan. "Assimilation and processing of observation data obtained by satellite earth sensing for monitoring the current state of heterogeneous objects on the water surface." E3S Web of Conferences 224 (2020): 02030. http://dx.doi.org/10.1051/e3sconf/202022402030.
Повний текст джерелаАнотація:
The study is devoted to the analysis of satellite observations data assimilation to discover the necessary information for developing and verifying mathematical models of hydrodynamics and biological shallowwater kinetics. The use of satellite earth sensing data is taken to enhance information base. The possible use of neural networks with optical flow computation is considered in the study. The objective of the study is to develop a software tool used to identify the initial conditions in mathematical modeling of hydrobilogical shallow-water processes.
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Masselot, A., and B. Chopard. "A Multiparticle Lattice-Gas Model for Hydrodynamics." International Journal of Modern Physics C 09, no. 08 (December 1998): 1221–30. http://dx.doi.org/10.1142/s0129183198001102.
Повний текст джерелаАнотація:
Cellular automata (CA) and lattice-Boltzmann (LB) models are two possible approaches to simulate fluid-like systems. CA models keep track of the many-body correlations and provide a description of the fluctuations. However, they lead to a noisy dynamics and impose strong restrictions on the possible viscosity values. On the other hand, LB models are numerically more efficient and offer much more flexibility to adjust the fluid parameters, but they neglect fluctuations. Here we discuss a multiparticle lattice model which reconciles both approaches. Our method is tested on Poiseuille flows and on the problem of ballistic annihilation in two dimensions for which the fluctuations are known to play an important role.
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Khvostov, Anatoly, Anatoly Khvostov, Viktor Ryazhskikh, Viktor Ryazhskikh, Gazibeg Magomedov, Gazibeg Magomedov, Aleksey Zhuravlev, and Aleksey Zhuravlev. "Matrix dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics in Simulink." Foods and Raw Materials 6, no. 2 (December 20, 2018): 483–92. http://dx.doi.org/10.21603/2308-4057-2018-2-483-492.
Повний текст джерелаАнотація:
The dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics are based on the systems of algebraic and differential equations that describe a change in the basic technological parameters. The main difficulty in using such models in MathWorks Simulink™ computer simulation systems is the representation of ordinary differential equations (ODE) and partial differential equations (PDE) that describe the dynamics of a process as a MathWorks Simulink™ block set. The study was aimed at developing an approach to the synthesis of matrix dynamic models of elements of technological systems with perfect mixing and plug-flow hydrodynamics that allows for transition from PDE to an ODE system on the basis of matrix representation of discretization of coordinate derivatives. A sugar syrup cooler was chosen as an object of modeling. The mathematical model of the cooler is formalized by a set of perfect reactors. The simulation results showed that the mathematical model adequately describes the main regularities of the process, the deviation of the calculated data from the regulations did not exceed 10%. The proposed approach significantly simplifies the study and modernization of the current and the development of new technological equipment, as well as the synthesis of algorithms for controlling the processes therein.
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SAVVIDIS, Y. G., M. G. DODOU, Y. N. KRESTENITIS, and C. G. KOUTITAS. "Modeling of the upwelling hydrodynamics in the Aegean Sea." Mediterranean Marine Science 5, no. 1 (June 1, 2004): 5. http://dx.doi.org/10.12681/mms.205.
Повний текст джерелаАнотація:
The special features of the hydrodynamic circulation in the Aegean Sea referring to the development of regional upwelling coastal zones are studied by means of a mathematical model. The modeling effort is focused on the tracing of coastal areas, where upwelling events are frequently observed during the summer meteorological conditions. These areas are characterized by the enrichment of surface waters with nutrients and, consequently, increased fish production. The phenomenon is studied by the use of a two-layer mathematical model comprising the surface heated zone and the rest of the water column. The numerical solution of the model is based on the finite differences method. The wind shear applied over the stratified basin, with predefined density stratification and initial water-layers thickness, and the gravity and Coriolis forces taken into account, constitute the basic external factors for the generation of the hydrodynamic circulation in the area of the Aegean Sea. The calibration and the validation of the model are performed by the comparison of the model output to the data and observations reported in valid scientific sources. The aim of the paper is to demonstrate the significant contribution of numerical models to the better understanding of the hydrodynamics governing the Aegean water circulation as well as the tracing of upwelling zones.
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Ferreira, Rui M. L., Mário J. Franca, João G. A. B. Leal, and António H. Cardoso. "Mathematical modelling of shallow flows: Closure models drawn from grain-scale mechanics of sediment transport and flow hydrodynamicsThis paper is one of a selection of papers in this Special Issue in honour of Professor M. Selim Yalin (1925–2007)." Canadian Journal of Civil Engineering 36, no. 10 (October 2009): 1605–21. http://dx.doi.org/10.1139/l09-033.
Повний текст джерелаАнотація:
Mathematical modelling of river processes is, nowadays, a key element in river engineering and planning. River modelling tools should rest on conceptual models drawn from mechanics of sediment transport, river mechanics, and river hydrodynamics. The objectives of the present work are (i) to describe conceptual models of sediment transport, deduced from grain-scale mechanics of sediment transport and turbulent flow hydrodynamics, and (ii) to present solutions to specific river morphology problems. The conceptual models described are applicable to the morphologic evolution of rivers subjected to the transport of poorly sorted sediment mixtures at low shear stresses and to geomorphic flows featuring intense sediment transport at high shear stresses. In common, these applications share the fact that sediment transport and flow resistance depend, essentially, on grain-scale phenomena. The idealized flow structures are presented and discussed. Numerical solutions for equilibrium and nonequilibrium sediment transport are presented and compared with laboratory and field data.
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Quintela, Pedro, Jean Carlos Pérez Parra, Lelly Useche Castro, and Miguel Lapo Palacios. "Simulation of Transient Flow in Gas Pipelines Using the Finite Volume Method." Revista Científica y Tecnológica UPSE 7, no. 2 (December 4, 2020): 17–26. http://dx.doi.org/10.26423/rctu.v7i2.534.
Повний текст джерелаАнотація:
The transient flow analysis is fundamental to the simulation of natural gas process, in order to adjust the system to real operative conditions and to obtain the highest level of efficiency, compliance and reliability. The simulation of natural gas pipelines and networks requires mathematical models that describe flow properties. Some models that have been developed year after year based on the laws of fluid mechanics that govern this process, interpreted as a system of equations difficult to solve. This investigation describes the fully implicit finite volume method for natural gas pipeline flow calculation under isothermal conditions and transient regime. The simplification, discretization scheme and implementation equations are approached throughout this paper. The model was subjected to two evaluations: sinusoidal variation of the mass flow and opening-closing valve at the outlet of the pipeline, it is compared with two models: fully implicit finite difference method and method of characteristics. This method proved to be efficient in the simulations of slow and fast transients, coinciding the flow oscillations with the natural frequency of natural gas pipeline.
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Shtykov, R. A. "Automation of the control process of a gas pipeline network with a complex topological structure." Journal of Physics: Conference Series 2182, no. 1 (March 1, 2022): 012011. http://dx.doi.org/10.1088/1742-6596/2182/1/012011.
Повний текст джерелаАнотація:
Abstract The reliability of the gas pipeline network is determined by the perfection of the structures, the precise fullfilament of the conditions of its operation, ensuring the coordination of the flow parameters in the pipe with the parameters of the blowers. Deviation from the established mode of operation in gas pipelines can affect the stability of the system. With a significant deviation from the operating mode, various features arise, both kinematic and dynamic deviations in the flow, which leads to unstable operation of the system. Therefore, it is necessary to automate the control processes of the pipeline gas network during gas transportation, which will be based on the results of mathematical modelling of mass transfer processes in pipes to determine the main flow parameters. It is also known that the main losses and changes in flow parameters in pipelines occur along the entire length of the linear sections of the network. Therefore, to adapt these changes to specific objects, it is necessary to use more accurate mathematical models that allow to adequately control the processes in the network based on automated control systems.