Journal articles on the topic 'Statistical approach to fluid mechanics'
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1
Peng, X. F., Y. Tien, and D. J. Lee. "Bubble nucleation in microchannels: statistical mechanics approach." International Journal of Heat and Mass Transfer 44, no. 15 (August 2001): 2957–64. http://dx.doi.org/10.1016/s0017-9310(00)00323-9.
2
Venaille, A., L. Gostiaux, and J. Sommeria. "A statistical mechanics approach to mixing in stratified fluids." Journal of Fluid Mechanics 810 (December 1, 2016): 554–83. http://dx.doi.org/10.1017/jfm.2016.721.
Abstract:
Predicting how much mixing occurs when a given amount of energy is injected into a Boussinesq fluid is a long-standing problem in stratified turbulence. The huge number of degrees of freedom involved in these processes renders extremely difficult a deterministic approach to the problem. Here we present a statistical mechanics approach yielding a prediction for a cumulative, global mixing efficiency as a function of a global Richardson number and the background buoyancy profile. Assuming random evolution through turbulent stirring, the theory predicts that the inviscid, adiabatic dynamics is attracted irreversibly towards an equilibrium state characterised by a smooth, stable buoyancy profile at a coarse-grained level, upon which are fine-scale fluctuations of velocity and buoyancy. The convergence towards a coarse-grained buoyancy profile different from the initial one corresponds to an irreversible increase of potential energy, and the efficiency of mixing is quantified as the ratio of this potential energy increase to the total energy injected into the system. The remaining part of the energy is lost into small-scale fluctuations. We show that for sufficiently large Richardson number, there is equipartition between potential and kinetic energy, provided that the background buoyancy profile is strictly monotonic. This yields a mixing efficiency of 0.25, which provides statistical mechanics support for previous predictions based on phenomenological kinematics arguments. In the general case, the cumulative, global mixing efficiency predicted by the equilibrium theory can be computed using an algorithm based on a maximum entropy production principle. It is shown in particular that the variation of mixing efficiency with the Richardson number strongly depends on the background buoyancy profile. This approach could be useful to the understanding of mixing in stratified turbulence in the limit of large Reynolds and Péclet numbers.
3
Becattini, Francesco, Matteo Buzzegoli, and Eduardo Grossi. "Reworking Zubarev’s Approach to Nonequilibrium Quantum Statistical Mechanics." Particles 2, no. 2 (April 8, 2019): 197–207. http://dx.doi.org/10.3390/particles2020014.
Abstract:
In this work, the nonequilibrium density operator approach introduced by Zubarev more than 50 years ago to describe quantum systems at a local thermodynamic equilibrium is revisited. This method, which was used to obtain the first “Kubo” formula of shear viscosity, is especially suitable to describe quantum effects in fluids. This feature makes it a viable tool to describe the physics of Quark–Gluon Plasma in relativistic nuclear collisions.
4
RICKAYZEN, GERALD, and JACK G. POWLES. "A collapsing bubble in a fluid: a statistical mechanical approach." Molecular Physics 100, no. 24 (December 20, 2002): 3823–28. http://dx.doi.org/10.1080/0026897021000016693.
5
Zhou, Shiqi. "Statistical mechanics approach to inhomogeneous van der Waals fluids." Molecular Simulation 32, no. 14 (December 2006): 1165–77. http://dx.doi.org/10.1080/08927020601071740.
6
Shi-Qi, Zhou, Chen Hong, Ling Si-Li, Xiang Xian-Wei, and Zhang Xiao-Qi. "Statistical Mechanics Approach for Uniform and Non-uniform Fluid with Hard Core and Interaction Tail." Communications in Theoretical Physics 39, no. 3 (March 15, 2003): 331–36. http://dx.doi.org/10.1088/0253-6102/39/3/331.
7
Alastuey, A. "Statistical Mechanics of Quantum Plasmas Path Integral Formalism." International Astronomical Union Colloquium 147 (1994): 43–77. http://dx.doi.org/10.1017/s0252921100026312.
Abstract:
AbstractIn this review, we consider a quantum Coulomb fluid made of charged point particles (typically electrons and nuclei). We describe various formalisms which start from the first principles of statistical mechanics. These methods allow systematic calculations of the equilibrium quantities in some particular limits. The effective-potential method is evocated first, as well as its application to the derivation of low-density expansions. We also sketch the basic outlines of the standard many-body perturbation theory. This approach is well suited for calculating expansions at high density (for Fermions) or at high temperature. Eventually, we present the Feynman-Kac path integral representation which leads to the introduction of an auxiliary classical system made of extended objects, i.e., filaments (also called “polymers”). The familiar Abe-Meeron diagrammatic series are then generalized in the framework of this representation. The truncations of the corresponding virial-like expansions provide equations of state which are asymptotically exact in the low-density limit at fixed temperature. The usefulness of such equations for describing the inner regions of the sun is briefly illustrated.
8
Brandyshev, Petr E., and Yury A. Budkov. "Statistical field theory of mechanical stresses in Coulomb fluids: general covariant approach vs Noether’s theorem." Journal of Statistical Mechanics: Theory and Experiment 2023, no. 12 (December 1, 2023): 123206. http://dx.doi.org/10.1088/1742-5468/ad0f8e.
Abstract:
Abstract In this paper, we introduce a statistical field theory that describes the macroscopic mechanical forces in inhomogeneous Coulomb fluids. Our approach employs the generalization of Noether’s first theorem for the case of a fluctuating order parameter to calculate the stress tensor for Coulomb fluids. This tensor encompasses the mean-field stress tensor and fluctuation corrections derived through the one-loop approximation. The correction for fluctuations includes a term that accounts for the thermal fluctuations of the local electrostatic potential and field in the vicinity of the mean-field configuration. This correlation stress tensor determines how electrostatic correlation affects local stresses in a nonuniform Coulomb fluid. We also use a previously formulated general covariant methodology (Brandyshev and Budkov 2023 J. Chem. Phys. 158 174114) in conjunction with a functional Legendre transformation method and derive within it the same total stress tensor. We would like to emphasize that our general approaches are applicable not only to Coulomb fluids but also to nonionic simple or complex fluids, for which the field-theoretic Hamiltonian is known as a function of the relevant scalar order parameters.
9
Saeed Shahsavari, Mehran Moradi, and Pooya Torkaman. "A Quasi-Statistical Approach to the Boltzmann Entropy Equation Based on a Novel Energy Conservation Principle." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 101, no. 2 (January 20, 2023): 99–110. http://dx.doi.org/10.37934/arfmts.101.2.99110.
Abstract:
Boltzmann entropy equation is gained according to the statistical mechanics directly and general dependence between entropy and probability is obtained. Based on the second law of thermodynamics with a glance at the Boltzmann entropy equation, it can be deduced that physical processes are done in a direction that the probability of the system and total entropy increase. In fact, the possible process performing states and their entropy variations will be determined at a specific energy level. In this paper, an entropy equation is gained by using a new quasi-statistical approach to the physical processes as well as a novel energy conservation principle. The variation of the "energy structure equation”, as an equation to formulate the performed process using activated energy components of the system and their dependence, is studied in different possible paths by using the energy conservation principle directly. Despite the classical mechanics that all particles are studied, in the novel approach, "particular processes" as all processes that have the same active independent energy components are studied at "various conditions"; in other words, all conditions that same energy amount is applied to the system. One of the advantages of this novel approach is that the volume of the needed calculations will be decreased mainly in comparison with the Boltzmann entropy equation. Dependence of the entropy and rate of the energy components is gained from the novel energy conservation principle. The gained relation, expressed by energy components of the system, is considered with no constraints on the structure of the system but has a common basis with the Boltzmann entropy equation. In fact, by using a novel macroscopic-statistical approach, the entropy variation of a physical system is studied.
10
ALDROVANDI, R., R. R. CUZINATTO, and L. G. MEDEIROS. "INTERACTING CONSTITUENTS IN COSMOLOGY." International Journal of Modern Physics D 17, no. 06 (June 2008): 857–79. http://dx.doi.org/10.1142/s0218271808012541.
Abstract:
Universe evolution, as described by Friedmann's equations, is determined by source terms fixed by the choice of pressure × energy density equations of state p(ρ). The usual approach in cosmology considers equations of state accounting only for kinematic terms, ignoring the contribution from the interactions between the particles constituting the source fluid. In this work the importance of these neglected terms is emphasized. A systematic method, based on the statistical mechanics of real fluids, is proposed to include them. A toy model is presented which shows how such interaction terms could be applied to engender significant cosmological effects.
11
HOSOTANI, YUTAKA. "NEUTRAL AND CHARGED ANYON FLUIDS." International Journal of Modern Physics B 07, no. 12 (May 30, 1993): 2219–323. http://dx.doi.org/10.1142/s0217979293002857.
Abstract:
Properties of neutral and charged anyon fluids are examined, with the main focus on the question of whether or not a charged anyon fluid exhibits a superconductivity at zero and finite temperature. Quantum mechanics of anyon fluids is precisely described by Chern-Simons gauge theory. The random phase approximation (RPA), the linearized self-consistent field method (SCF), and the hydrodynamic approach employed in the early analysis of anyon fluids are all equivalent. Relations and differences between neutral and charged anyon fluids are discussed. It is necessary to go beyond RPA and the linearized SCF, and possively beyond the Hartree-Fock approximation, to correctly describe various phenomena such as the flux quantization, vortex formation, and phase transition.
12
GÖlz, Paul, Anson Kahng, Simon Mackenzie, and Ariel D. Procaccia. "The Fluid Mechanics of Liquid Democracy." ACM Transactions on Economics and Computation 9, no. 4 (December 31, 2021): 1–39. http://dx.doi.org/10.1145/3485012.
Abstract:
Liquid democracy is the principle of making collective decisions by letting agents transitively delegate their votes. Despite its significant appeal, it has become apparent that a weakness of liquid democracy is that a small subset of agents may gain massive influence. To address this, we propose to change the current practice by allowing agents to specify multiple delegation options instead of just one. Much like in nature, where—fluid mechanics teaches us—liquid maintains an equal level in connected vessels, we seek to control the flow of votes in a way that balances influence as much as possible. Specifically, we analyze the problem of choosing delegations to approximately minimize the maximum number of votes entrusted to any agent by drawing connections to the literature on confluent flow. We also introduce a random graph model for liquid democracy and use it to demonstrate the benefits of our approach both theoretically and empirically.
13
Zloshchastiev, Konstantin G. "Density Operator Approach to Turbulent Flows in Plasma and Atmospheric Fluids." Universe 6, no. 11 (November 20, 2020): 216. http://dx.doi.org/10.3390/universe6110216.
Abstract:
We formulate a statistical wave-mechanical approach to describe dissipation and instabilities in two-dimensional turbulent flows of magnetized plasmas and atmospheric fluids, such as drift and Rossby waves. This is made possible by the existence of Hilbert space, associated with the electric potential of plasma or stream function of atmospheric fluid. We therefore regard such turbulent flows as macroscopic wave-mechanical phenomena, driven by the non-Hermitian Hamiltonian operator we derive, whose anti-Hermitian component is attributed to an effect of the environment. Introducing a wave-mechanical density operator for the statistical ensembles of waves, we formulate master equations and define observables: such as the enstrophy and energy of both the waves and zonal flow as statistical averages. We establish that our open system can generally follow two types of time evolution, depending on whether the environment hinders or assists the system’s stability and integrity. We also consider a phase-space formulation of the theory, including the geometrical-optic limit and beyond, and study the conservation laws of physical observables. It is thus shown that the approach predicts various mechanisms of energy and enstrophy exchange between drift waves and zonal flow, which were hitherto overlooked in models based on wave kinetic equations.
14
Shivaram, A. C., and K. V. Gangadharan. "Statistical modeling of a magneto-rheological fluid damper using the design of experiments approach." Smart Materials and Structures 16, no. 4 (July 5, 2007): 1310–14. http://dx.doi.org/10.1088/0964-1726/16/4/044.
15
Abraham, Farid F., Noam Bernstein, Jeremy Q. Broughton, and Daryl Hess. "Dynamic Fracture of Silicon: Concurrent Simulation of Quantum Electrons, Classical Atoms, and the Continuum Solid." MRS Bulletin 25, no. 5 (May 2000): 27–32. http://dx.doi.org/10.1557/mrs2000.70.
Abstract:
Our understanding of materials phenomena is based on a hierarchy of physical descriptions spanning the space-time regimes of electrons, atoms, and matter and given by the theories of quantum mechanics, statistical mechanics, and continuum mechanics. The pioneering work of Clementi and co-workers provides a lucid example of the traditional approach to incorporating multiscale phenomena associated with these three mechanics. Using quantum mechanics, they evaluated the interactions of several water molecules. From this data base, they created an empirical potential for use in atomistic mechanics and evaluated the viscosity of water. From this computed viscosity, they performed a fluid-dynamics simulation to predict the tidal circulation in Buzzard's Bay. This is a powerful example of the sequential coupling of length and time scales: a series of calculations is used as input to the next rung up the length/time-scale ladder.
16
Peredo-Ortíz, R., and M. Hernández-Contreras. "Diffusion microrheology of ferrofluids." Revista Mexicana de Física 64, no. 1 (February 8, 2018): 82. http://dx.doi.org/10.31349/revmexfis.64.82.
Abstract:
We provide a statistical mechanics approach to study the linear microrheology of thermally equilibrated and homogeneous ferrofluids. Theexpressions for the elastic and loss moduli depend on the bulk microstructure of the magnetic fluid determined by the structure factor of thesuspension of magnetic particles. The comparison of the predicted microrheology with computer simulations confirms that as a function ofrelaxation frequency of thermal fluctuations of the particle concentration both theory and simulations have the same trends. At very shortfrequencies the viscous modulus relates to the translational and rotational self-diffusion coefficients of a ferro-particle.
17
Jiang, Zhuo, Zong-Guo Zhang, Jing-Jing Li, and Hong-Wei Yang. "Analysis of Lie Symmetries with Conservation Laws and Solutions of Generalized (4 + 1)-Dimensional Time-Fractional Fokas Equation." Fractal and Fractional 6, no. 2 (February 13, 2022): 108. http://dx.doi.org/10.3390/fractalfract6020108.
Abstract:
High-dimensional fractional equations research is a cutting-edge field with significant practical and theoretical implications in mathematics, physics, biological fluid mechanics, and other fields. Firstly, in this paper, the (4 + 1)-dimensional time-fractional Fokas equation in a higher-dimensional integrable system is studied by using semi-inverse and fractional variational theory. Then, the Lie symmetry analysis and conservation law analysis are carried out for the higher dimensional fractional order model with the symmetry of fractional order. Finally, the fractional-order equation is solved using the bilinear approach to produce the rogue wave and multi-soliton solutions, and the fractional equation is numerically solved using the Radial Basis Functions (RBFs) method.
18
Lin, Hsin-Hung, Jui-Hung Cheng, and Chi-Hsiung Chen. "Application of Gray Relational Analysis and Computational Fluid Dynamics to the Statistical Techniques of Product Designs." Symmetry 12, no. 2 (February 3, 2020): 227. http://dx.doi.org/10.3390/sym12020227.
Abstract:
During the development of fan products, designers often encounter gray areas when creating new designs. Without clear design goals, development efficiency is usually reduced, and fans are the best solution for studying symmetry or asymmetry. Therefore, fan designers need to figure out an optimization approach that can simplify the fan development process and reduce associated costs. This study provides a new statistical approach using gray relational analysis (GRA) to analyze and optimize the parameters of a particular fan design. During the research, it was found that the single fan uses an asymmetry concept with a single blade as the design, while the operation of double fans is a symmetry concept. The results indicated that the proposed mechanical operations could enhance the variety of product designs and reduce costs. Moreover, this approach can relieve designers from unnecessary effort during the development process and also effectively reduce the product development time.
19
ZHANG, CHENGYUAN, XIAOYAN LIU, DAOYING XI, and QUANSHENG LIU. "AN ROCK-PHYSICS-BASED COMPLEX PORE-FLUID-DISTRIBUTION MODEL TO SEISMIC DYNAMICAL RESPONSE." International Journal of Modern Physics B 22, no. 09n11 (April 30, 2008): 1437–42. http://dx.doi.org/10.1142/s021797920804689x.
Abstract:
It is very important to know how the reservoir rock and its fluid properties are linked to seismic dynamic response. Literatures show that there are a variety of rock-physics models such as the most famous Biot-Gassmann equation aimed at the relationship between seismic velocity and liquid saturation. Most of these models make a fundamental assumption of one fluid phase or homogeneous phase within the pore volume. In this paper, we discuss possible seismic velocities change in a two immiscible pore fluids (i.e. water-gas) saturated reservoir with patchy saturation distribution. It is found that P-wave velocity of a reservoir rock with the same saturation but different pore fluid distribution exhibits noticeable variation and deviate overall from Gassmann's results. We use DEM theory to explain this phenomenon. It belongs to hybrid approach in rock-physics modeling and can handle complex pore-fluid-distribution cases. Based on the modeling study, we found that various fluid-distribution models may significantly affect the modulus and P-wave velocity. The seismic reflection time, amplitude and phase characteristics may change with the choice of pore-fluid-distribution models. Relevant rock mechanical experiments indicate the same trend of seismic responses. It also be proven by seismic reservoir monitoring experiment (time lapse study) that incorrect conclusion may be drawn about the strong seismic reflection in pure Utsira Sand if the microscopic pore-fluid-distribution effects are not taken into account.
20
Bomzon, Ze’ev, Martin M. Knight, Dan L. Bader, and Eitan Kimmel. "Mitochondrial Dynamics in Chondrocytes and Their Connection to the Mechanical Properties of the Cytoplasm." Journal of Biomechanical Engineering 128, no. 5 (February 12, 2006): 674–79. http://dx.doi.org/10.1115/1.2246239.
Abstract:
Background: The motion and redistribution of intracellular organelles is a fundamental process in cells. Organelle motion is a complex phenomenon that depends on a large number of variables including the shape of the organelle, the type of motors with which the organelles are associated, and the mechanical properties of the cytoplasm. This paper presents a study that characterizes the diffusive motion of mitochondria in chondrocytes seeded in agarose constructs and what this implies about the mechanical properties of the cytoplasm. Method of approach: Images showing mitochondrial motion in individual cells at 30s intervals for 15min were captured with a confocal microscope. Digital image correlation was used to quantify the motion of the mitochondria, and the mean square displacement (MSD) was calculated. Statistical tools for testing whether the characteristic motion of mitochondria varied throughout the cell were developed. Calculations based on statistical mechanics were used to establish connections between the measured MSDs and the mechanical nature of the cytoplasm. Results: The average MSD of the mitochondria varied with time according to a power law with the power term greater than 1, indicating that mitochondrial motion can be viewed as a combination of diffusion and directional motion. Statistical analysis revealed that the motion of the mitochondria was not uniform throughout the cell, and that the diffusion coefficient may vary by over 50%, indicating intracellular heterogeneity. High correlations were found between movements of mitochondria when they were less than 2μm apart. The correlation is probably due to viscoelastic properties of the cytoplasm. Theoretical analysis based on statistical mechanics suggests that directed diffusion can only occur in a material that behaves like a fluid on large time scales. Conclusions: The study shows that mitochondria in different regions of the cell experience different characteristic motions. This suggests that the cytoplasm is a heterogeneous viscoelastic material. The study provides new insight into the motion of mitochondria in chondrocytes and its connection with the mechanical properties of the cytoplasm.
21
Fateev, V. A., R. De Pietri, and E. Onofri. "Exact and semiclassical approach to a class of singular integral operators arising in fluid mechanics and quantum field theory." Journal of Physics A: Mathematical and General 37, no. 47 (November 11, 2004): 11379–89. http://dx.doi.org/10.1088/0305-4470/37/47/007.
22
Vidal, Alvaro, Carlos Rodriguez, Phoevos Koukouvinis, Manolis Gavaises, and Mark A. McHugh. "Modelling of Diesel fuel properties through its surrogates using Perturbed-Chain, Statistical Associating Fluid Theory." International Journal of Engine Research 21, no. 7 (September 28, 2018): 1118–33. http://dx.doi.org/10.1177/1468087418801712.
Abstract:
The Perturbed-Chain, Statistical Associating Fluid Theory equation of state is utilised to model the effect of pressure and temperature on the density, volatility and viscosity of four Diesel surrogates; these calculated properties are then compared to the properties of several Diesel fuels. Perturbed-Chain, Statistical Associating Fluid Theory calculations are performed using different sources for the pure component parameters. One source utilises literature values obtained from fitting vapour pressure and saturated liquid density data or from correlations based on these parameters. The second source utilises a group contribution method based on the chemical structure of each compound. Both modelling methods deliver similar estimations for surrogate density and volatility that are in close agreement with experimental results obtained at ambient pressure. Surrogate viscosity is calculated using the entropy scaling model with a new mixing rule for calculating mixture model parameters. The closest match of the surrogates to Diesel fuel properties provides mean deviations of 1.7% in density, 2.9% in volatility and 8.3% in viscosity. The Perturbed-Chain, Statistical Associating Fluid Theory results are compared to calculations using the Peng–Robinson equation of state; the greater performance of the Perturbed-Chain, Statistical Associating Fluid Theory approach for calculating fluid properties is demonstrated. Finally, an eight-component surrogate, with properties at high pressure and temperature predicted with the group contribution Perturbed-Chain, Statistical Associating Fluid Theory method, yields the best match for Diesel properties with a combined mean absolute deviation of 7.1% from experimental data found in the literature for conditions up to 373°K and 500 MPa. These results demonstrate the predictive capability of a state-of-the-art equation of state for Diesel fuels at extreme engine operating conditions.
23
Kolesnichenko, Aleksandr Vladimirovich. "Construction of relativistic hydrodynamics of a multicomponent fluid. 1. The method of relativistic irreversible thermodynamics." Keldysh Institute Preprints, no. 2 (2023): 1–44. http://dx.doi.org/10.20948/prepr-2023-2.
Abstract:
The paper develops relativistic mechanics and irreversible thermodynamics of a cosmological liquid mixture in which thermal conduction, diffusion, viscous flow and their crossing phenomena can occur. The main thermodynamic fields that occur in relativistic irreversible thermodynamics are defined as statistical expressions using relativistic kinetics. The effects of the Eckart approach on the choice of the hydrodynamic velocity are shown. The equations of relativistic multicomponent hydrodynamics for local densities of momentum, energy and number of particles of different sort, are also obtained from the fundamental conservation laws of relativistic thermodynamics.. The energy conservation law (the first beginning of relativistic thermodynamics) is formulated. Covariant Gibbs relation and local form of the second principle of thermodynamics in the presence of entropy source were derived in order to obtain determining relations linearly connecting fluxes with corresponding thermodynamic forces. Equivalent forms of relativistic entropy production in the form of a bilinear expression in terms of thermodynamic forces were obtained. A new cross-effect between diffusion and conduction arising from the relativistic term in the thermodynamic force coupled to the heat flux is discussed. The synopsis presented is of interest for relativistic mechanics, astrophysics, and cosmology.
24
Raza, Jawad, Fateh Mebarek-Oudina, and B. Mahanthesh. "Magnetohydrodynamic flow of nano Williamson fluid generated by stretching plate with multiple slips." Multidiscipline Modeling in Materials and Structures 15, no. 5 (September 2, 2019): 871–94. http://dx.doi.org/10.1108/mmms-11-2018-0183.
Abstract:
Purpose The purpose of this paper is to present an exploration of multiple slips and temperature dependent thermal conductivity effects on the flow of nano Williamson fluid over a slendering stretching plate in the presence of Joule and viscous heating aspects. The effectiveness of nanoparticles is deliberated by considering Brownian moment and thermophoresis slip mechanisms. The effects of magnetism and radiative heat are also deployed. Design/methodology/approach The governing partial differential equations are non-dimensionalized and reduced to multi-degree ordinary differential equations via suitable similarity variables. The subsequent non-linear problem treated for numerical results. To measure the amount of increase/decrease in skin friction coefficient, Nusselt number and Sherwood number, the slope of linear regression line through the data points are calculated. Statistical approach is implemented to analyze the heat transfer rate. Findings The results show that temperature distribution across the flow decreases with thermal conductivity parameter. The maximum friction factor is ascertained at stronger magnetic field. Originality/value In the current paper, the magneto-nano Williamson fluid flow inspired by a stretching sheet of variable thickness is examined numerically. The rationale of the present study is to generalize the studies of Mebarek-Oudina and Makinde (2018) and Williamson (1929).
25
Mishra, S. R., Subhajit Panda, Mansoor Alshehri, Nehad Ali Shah, and Jae Dong Chung. "Sensitivity analysis on optimizing heat transfer rate in hybrid nanofluid flow over a permeable surface for the power law heat flux model: Response surface methodology with ANOVA test." AIMS Mathematics 9, no. 5 (2024): 12700–12725. http://dx.doi.org/10.3934/math.2024621.
Abstract:
<abstract> <p>Joule dissipation has an important role in the conversion of mechanical energy to heat within a fluid due to the internal friction and viscosity. Moreover, Darcy friction is a measure of the resistance to flow in a porous medium. In response to the efficient heat transfer performance, a robust statistical approach was established to optimize the heat transfer rate in a two-dimensional flow of a nanofluid over a permeable surface embedded with a porous matrix. The electrically conducive fluid affected the flow phenomena to include a carbon nanotube nanoparticle in the conventional liquid water for the enhanced heat transfer properties; additionally, the power-law heat flux model was considered. Appropriate transformation rules were adopted to obtain a non-dimensional system that brought a developed model equipped with several factors. The traditional numerical technique (i.e., shooting based Runge-Kutta) was proposed to handle the coupled nonlinear system. Furthermore, the statistical response surface methodology (RSM) was adopted to obtain an efficient optimized model for the heat transportation rate of the considered factors. An analysis of variance (ANOVA) was utilized to validate the result of the regression analysis. However, it was evident that the nanoparticle concentrations were useful to augment the fluid velocity and the temperature distributions; the statistical approach adopted for the heat transfer rate displayed an optimized effect as compared to a conventional effect.</p> </abstract>
26
Bianucci, Marco. "Nonconventional fluctuation dissipation process in non-Hamiltonian dynamical systems." International Journal of Modern Physics B 30, no. 15 (June 16, 2016): 1541004. http://dx.doi.org/10.1142/s0217979215410040.
Abstract:
Here, we introduce a statistical approach derived from dynamics, for the study of the geophysical fluid dynamics phenomena characterized by a weak interaction among the variables of interest and the rest of the system. The approach is reminiscent of the one developed some years ago [M. Bianucci, R. Mannella, P. Grigolini and B. J. West, Phys. Rev. E 51, 3002 (1995)] to derive statistical mechanics of macroscopic variables on interest starting from Hamiltonian microscopic dynamics. However, in the present work, we are interested to generalize this approach beyond the context of the foundation of thermodynamics, in fact, we take into account the cases where the system of interest could be non-Hamiltonian (dissipative) and also the interaction with the irrelevant part can be of a more general type than Hamiltonian. As such example, we will refer to a typical case from geophysical fluid dynamics: the complex ocean–atmosphere interaction that gives rise to the El Niño Southern Oscillation (ENSO). Here, changing all the scales, the role of the “microscopic” system is played by the atmosphere, while the ocean (or some ocean variables) plays the role of the intrinsically dissipative macroscopic system of interest. Thus, the chaotic and divergent features of the fast atmosphere dynamics remains in the decaying properties of the correlation functions and of the response function of the atmosphere variables, while the exponential separation of the perturbed (or close) single trajectories does not play a direct role. In the present paper, we face this problem in the frame of a not formal Langevin approach, limiting our discussion to physically based rather than mathematics arguments. Elsewhere, we obtain these results via a much more formal procedure, using the Zwanzing projection method and some elements from the Lie Algebra field.
27
Gao, Peng, and Jin-jun Zhang. "New assessment of friction factor correlations for power law fluids in turbulent pipe flow: A statistical approach." Journal of Central South University of Technology 14, S1 (February 2007): 77–81. http://dx.doi.org/10.1007/s11771-007-0219-5.
28
Graczyk, Mateusz, Torgeir Moan, and Olav Rognebakke. "Probabilistic Analysis of Characteristic Pressure for LNG Tanks." Journal of Offshore Mechanics and Arctic Engineering 128, no. 2 (November 8, 2005): 133–44. http://dx.doi.org/10.1115/1.2185128.
Abstract:
Background. New challenges in LNG shipping, such as ship size growth, trading routes with more severe weather conditions, need for operating with unrestricted filling level and new propulsion systems attract very much attention in marine and offshore oriented community. One of the main concerns is the prediction of loads caused by violent fluid motion in cargo tanks. In the paper we address the problem of determining characteristic extreme values of sloshing pressures for structural design. This involves estimating ship motion in a long-term period, fluid motion in the tank, excited pressures, and relevant structural responses. Method of Approach. Ship motion analysis is based on linear strip theory. In order to investigate the dependence of the sloshing response on sea conditions, an approach based on statistical characteristics of the tank motion is utilized as well as a multimodal approach for fluid motion in a tank. However, an appropriate theoretical/numerical approach, which can be used for a realistic prediction of the most extreme pressure has not yet been developed. Thus, experiments are utilized for the most severe sea states for a chosen tank filling level. Results. Our main contribution in the paper includes the statistical analysis of experimental short term pressure distribution. The choice and fit of probability distribution models is addressed, with due account of different physical mechanisms causing impacts. The models are evaluated. The most critical tank areas for sloshing loads are briefly discussed. Appropriate dynamic response of the tank structure needs to be investigated by accounting for temporal and spatial distribution of sloshing loads. These two factors are also addressed in the paper. The variability of results obtained by processing data from multiple test runs is discussed. Conclusions. The three-parameter Weibull and generalized Pareto statistical models are fitted to the data and evaluated. They prove to accurately describe sloshing excited pressures. However, the highest data points are underestimated by the both distributions. Generalized Pareto model results in more conservative estimates. The threshold level of peaks used in a fit of generalized Pareto distribution was investigated. Based on this, it is set to a level of a 0.85–0.87 quantile of peak values. The big influence of spatial and temporal distribution on the estimates is reported. Uncertainty in measured pressures originating from inherent fluid motion variability exceeds the uncertainty resulting form ship motions' variability. Moreover, generalized Pareto model results in higher variability.
29
GOLDIN, GERALD A. "THE DIFFEOMORPHISM GROUP APPROACH TO NONLINEAR QUANTUM SYSTEMS." International Journal of Modern Physics B 06, no. 11n12 (June 1992): 1905–16. http://dx.doi.org/10.1142/s0217979292000931.
Abstract:
Unitary representations of diffeomorphism groups predict some unusual possibilities in quantum theory, including non-standard statistics and certain nonlinear effects. Many of the fundamental physical properties of “anyons” were first derived from their study by R. Menikoff, D.H. Sharp, and the author. This paper surveys new applications in two other domains: first (with Menikoff and Sharp) some surprising conclusions about the nature of quantum vortex configurations in ideal, incompressible fluids; second (with H.-D. Doebner) a natural description of dissipative quantum mechanics by means of a nonlinear Schrödinger equation different from the sort usually studied. Our equation follows from including a diffusion current in the equation of continuity.
30
Djeddou, Mokhtar, Amine Mehel, Georges Fokoua, Anne Tanière, and Patrick Chevrier. "On the application of statistical turbulence models to the simulation of airflow inside a car cabin." Physics of Fluids 35, no. 2 (February 2023): 025106. http://dx.doi.org/10.1063/5.0132677.
Abstract:
Computational fluid dynamics simulations of airflow inside a full-scale passenger car cabin are performed using the Reynolds averaged Navier–Stokes equations. The performance of a range of turbulence models is examined by reference to experimental results of the streamwise mean velocity and turbulence intensity profiles, obtained using the hot-wire anemometry technique at different locations inside the car cabin. The models include three linear eddy-viscosity-based variants, namely, the realizable k– ε, the renormalization group k– ε, and the shear-stress transport k– ω models. The baseline Reynolds stress model (BSL-RSM), a second-moment-closure variant, and an Explicit Algebraic Reynolds Stress Model (BSL-EARSM) are also investigated. Visualization of velocity vectors and streamlines in different longitudinal planes shows a similar airflow pattern. The flow topology is mainly characterized by jet flows developing from the dashboard air vents and extending to the back-seats compartment resulting in a large vortex structure. Additionally, a comparison between numerical and experimental results shows a relatively good agreement of the mean velocity profiles. However, all models exhibit some limitations in predicting the correct level of turbulence intensity. Moreover, the realizability of the modeled Reynolds stresses and the structure of turbulence are analyzed based on the anisotropy invariant mapping approach. All models reveal a few amounts of non-realizable solutions. The linear eddy-viscosity-based models return a prevailing isotropic turbulence state, while the BSL-RSM and the BSL-EARSM models display pronounced anisotropic turbulence states.
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Gupta, Munish Kumar, and PK Sood. "Machining comparison of aerospace materials considering minimum quantity cutting fluid: A clean and green approach." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 8 (December 13, 2016): 1445–64. http://dx.doi.org/10.1177/0954406216684158.
Abstract:
Efficient removal of heat from the chip formation zone in the machining of aerospace materials is quite crucial for attaining viability with respect to cost and productivity. The recently embraced cooling and lubrication method in the context of environmental friendly and sustainable manufacturing includes the application of minimum quantity cutting fluid. This article presents an experimental investigation, complemented with an evolutionary optimization technique, for studying the impact on cutting forces, surface roughness, tool wear, and chip control in the turning of the two aero-engine alloys (Inconel-800 and titanium-II) with or without using minimal-quantity cooling lubrication fluid. In addition, the multiple regression technique is applied to find the relationship between responses and input parameter such as cutting speed, feed rate, and approach angle. Afterward, the sensitivity analysis and analysis of variance (ANOVA) tests have been performed to test the statistical significance of proposed predictive models. At the end of work, the experimental data have been optimized through two evolutionary techniques, i.e. particle swarm optimization and bacterial foraging optimization, also compared to the much-used desirability technique. It has been concluded that the cooling option of applying minimum quantity cutting fluid proved beneficial for machining these aerospace materials. Moreover, the evolutionary techniques gave much more accurate results when compared to the desirability technique with particle swarm optimization and was concluded as the best one out of the three techniques on the basis of minimum average time taken and minimum percentage error.
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Kalateh, Farhoud, and Ali Koosheh. "Finite Element Analysis of Flexible Structure and Cavitating Nonlinear Acoustic Fluid Interaction under Shock Wave Loading." International Journal of Nonlinear Sciences and Numerical Simulation 19, no. 5 (July 26, 2018): 459–73. http://dx.doi.org/10.1515/ijnsns-2016-0135.
Abstract:
AbstractThis paper describes a numerical model and its finite element implementation that used to compute the cavitation effects on nonlinear acoustic fluid and adjacent flexible structure interaction. The system is composed of two sub-systems, namely, the fluid and the flexible flat plate. A fully coupled approach using iterative implicit partitioned scheme was implemented in the present work which can account for the effects associated whit a mutual interaction. This approach included a compressible nonlinear acoustic fluid Eulerian solver and a Lagrangian solver for the flexible structure both in finite element formulation. A novel implementation of acoustic cavitation was made possible with the introduction of a simplified one-fluid cavitation model. The element-by-element PCG (Preconditioned Conjugate Gradient) solver together with diagonal preconditioning is used to solve the large equation system resulting from the finite element discretization of the governing equation of fluid domain. The capability of three different cavitation model, as the cut-off model, Modified Schmidt model and developed model are compared with each other in the evaluation of plate vibration response. Simulation results are presented on a large size shock tube, in which planar shock waves were impacting in “face on” configuration flat plates mounted at tube's end. Results are presented to demonstrate the capability of proposed solver in simulating cavitating nonlinear acoustic fluid. Obtained results show that impact forces caused impinging shock wave and reloading by cavitating region collapse have a considerable effect on the dynamic response of flexible plate.
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Kichatinov, L. L. "Lagrangian approach to the mean-field electrodynamics for turbulent fluids with arbitrary conductivities." Journal of Fluid Mechanics 208 (November 1989): 115–26. http://dx.doi.org/10.1017/s002211208900279x.
Abstract:
A modification is made to the traditional Lagrangian approach to the derivation of the mean EMF of turbulent fluids which allows for finite conductivities. Consideration is confined to the case of homogeneous, isotropic but generally mirrornon-invariant and compressible turbulence. The eddy magnetic diffusivity and the coefficient α of the alpha-effect are expressed in terms of statistical moments of displacements of adjacent particles which undergo convective transport and microscopic diffusion in a turbulent flow. These expressions, being valid for arbitrary conductivities, reproduce known results in the cases of both very large and very small magnetic Reynolds numbers. Difficulties and advantages of the use of the results obtained for evaluations of the mean EMF are discussed.
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Song, Xinwei, Amy L. Throckmorton, Houston G. Wood, James F. Antaki, and Don B. Olsen. "Quantitative Evaluation of Blood Damage in a Centrifugal VAD by Computational Fluid Dynamics." Journal of Fluids Engineering 126, no. 3 (May 1, 2004): 410–18. http://dx.doi.org/10.1115/1.1758259.
Abstract:
This study explores a quantitative evaluation of blood damage that occurs in a continuous flow left ventricular assist device (LVAD) due to fluid stress. Computational fluid dynamics (CFD) analysis is used to track the shear stress history of 388 particle streaklines. The accumulation of shear and exposure time is integrated along the streaklines to evaluate the levels of blood trauma. This analysis, which includes viscous and turbulent stresses, provides a statistical estimate of possible damage to cells flowing through the pump. Since experimental data for hemolysis levels in our LVAD are not available, in vitro normalized index of hemolysis values for clinically available ventricular assist devices were compared to our damage indices. This approach allowed for an order of magnitude comparison between our estimations and experimentally measured hemolysis levels, which resulted in a reasonable correlation. This work ultimately demonstrates that CFD is a convenient and effective approach to analyze the Lagrangian behavior of blood in a heart assist device.
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Rodríguez-Martín, Manuel, Pablo Rodríguez-Gonzálvez, Alberto Sánchez-Patrocinio, and Javier Ramón Sánchez. "Short CFD Simulation Activities in the Context of Fluid-Mechanical Learning in a Multidisciplinary Student Body." Applied Sciences 9, no. 22 (November 10, 2019): 4809. http://dx.doi.org/10.3390/app9224809.
Abstract:
Simulation activities are a useful tool to improve competence in industrial engineering bachelors. Specifically, fluid simulation allows students to acquire important skills to strengthen their theoretical knowledge and improve their future professional career. However, these tools usually require long training times and they are usually not available in the subjects of B.Sc. degrees. In this article, a new methodology based on short lessons is raised and evaluated in the fluid-mechanical subject for students enrolled in three different bachelor degree groups: B.Sc. in Mechanical Engineering, B.Sc. in Electrical Engineering and B.Sc. in Electronic and Automatic Engineering. Statistical results show a good acceptance in terms of usability, learning, motivation, thinking over, satisfaction and scalability. Additionally, a machine-learning based approach was applied to find group peculiarities and differences among them in order to identify the need for further personalization of the learning activity.
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Rahimi, P., and C. A. Ward. "Effect of pressure on the rate of evaporation from capillaries: statistical rate theory approach." International Journal of Heat and Mass Transfer 47, no. 5 (February 2004): 877–86. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2003.08.024.
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STIPANOVIC, ARTHUR J. "COATED GLASS MICROSPHERES IN ERF APPLICATIONS." International Journal of Modern Physics B 15, no. 06n07 (March 20, 2001): 665–71. http://dx.doi.org/10.1142/s0217979201005131.
Abstract:
ER fluids (ERFs) typically consist of a concentrated dispersion of solid particles in a non-conducting base fluid. As a result, particle sedimentation represents a significant problem for many formulations since, in most cases, the particulate phase is of higher density than the base fluid. To remedy this situation, higher density fluids have been widely used in ERFs (ρ > 1.1 g/cc) rather than less expensive mineral oils that display lower densities (0.8-0.9 g/cc). An alternative approach to density "matching" has been explored by Qi and Shaw who have successfully developed ERF particles based on low density, micron-sized hollow glass "balloons" that are polymer coated. These microballons are commercially available from the PQ Corporation and they exhibit an effective density of 0.7 g/cc. Using these materials, it becomes possible to engineer ERF particles that are "neutrally buoyant" in mineral oils by adjusting the coating weight of an ER active polymer on the glass spheres. In this study, a simple solution coating process was developed exploiting the unique surface chemistry of glass which contains -Si-O-Si- and -Si-OH sites capable of hydrogen bonding with hydrophillic polymers. A number of water-soluble ionic polysaccharides were evaluated as coatings because of their ability to form hydrogen bonds with glass surfaces. A synthetic alcohol-soluble polymer, sulfonated polyphenylene oxide, was also evaluated because of its thermal stability and mechanical durability.
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RamReddy, Chetteti, and Teegala Pradeepa. "Non-similarity Solutions for Viscous Dissipation and Soret Effects in Micropolar Fluid over a Truncated Cone with Convective Boundary Condition: Spectral Quasilinearization Approach." International Journal of Nonlinear Sciences and Numerical Simulation 18, no. 5 (July 26, 2017): 327–42. http://dx.doi.org/10.1515/ijnsns-2016-0045.
Abstract:
AbstractThis article emphasizes the influence of convective boundary condition on mixed convection flow of a micropolar fluid over a truncated cone with Soret and viscous dissipation effects. The governing micropolar fluid flow equations are non-dimensionalized using suitable non-similarity transformations. Several authors have applied the spectral quasilinearization method to solve the ordinary differential equations, but here the resulting nonlinear partial differential equations are solved for non-similarity solution by using a newly developed method called the spectral quasilinearization method (SQLM). The comparison of convection process namely free, forced and mixed convection on the micropolar fluid is provided in detail. The convergence and error analysis are also discussed to test the accuracy of the spectral method. From the results, it perceived that with the rise in viscous dissipation parameter, the wall couple stress coefficient and Nusselt number reduce, but velocity, temperature, concentration, skin friction coefficient and Sherwood number increase for both in the absence and in the presence of Soret number.
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Malik, M. Y., and T. Salahuddin. "Numerical Solution of MHD Stagnation Point Flow of Williamson Fluid Model over a Stretching Cylinder." International Journal of Nonlinear Sciences and Numerical Simulation 16, no. 3-4 (June 1, 2015): 161–64. http://dx.doi.org/10.1515/ijnsns-2014-0035.
Abstract:
AbstractThe present paper deals with the numerical solution of magnetohydrodynamic (MHD) flow of Williamson fluid model over a stretching cylinder. The governing partial differential equation of Williamson fluid is converted into an ordinary differential equation using similarity transformations along with boundary layer approach, which is then solved numerically by applying the shooting method in conjunction with Runge–Kutta–Fehlberg method. The effect of different parameters on velocity profile is thoroughly examined through graphs and tables.
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Avgerinou, Sophia-Ekaterini, Eleni-Apostolia Anyfadi, Georgios Michas, and Filippos Vallianatos. "A Non-Extensive Statistical Physics View of the Temporal Properties of the Recent Aftershock Sequences of Strong Earthquakes in Greece." Applied Sciences 13, no. 3 (February 3, 2023): 1995. http://dx.doi.org/10.3390/app13031995.
Abstract:
Greece is one of Europe’s most seismically active areas. Seismic activity in Greece has been characterized by a series of strong earthquakes with magnitudes up to Mw = 7.0 over the last five years. In this article we focus on these strong events, namely the Mw6.0 Arkalochori (27 September 2021), the Mw6.3 Elassona (3 March 2021), the Mw7.0 Samos (30 October 2020), the Mw5.1 Parnitha (19 July 2019), the Mw6.6 Zakynthos (25 October 2018), the Mw6.5 Kos (20 July 2017) and the Mw6.1 Mytilene (12 June 2017) earthquakes. Based on the probability distributions of interevent times between the successive aftershock events, we investigate the temporal evolution of their aftershock sequences. We use a statistical mechanics model developed in the framework of Non-Extensive Statistical Physics (NESP) to approach the observed distributions. NESP provides a strictly necessary generalization of Boltzmann–Gibbs statistical mechanics for complex systems with memory effects, (multi)fractal geometries, and long-range interactions. We show how the NESP applicable to the temporal evolution of recent aftershock sequences in Greece, as well as the existence of a crossover behavior from power-law (q ≠ 1) to exponential (q = 1) scaling for longer interevent times. The observed behavior is further discussed in terms of superstatistics. In this way a stochastic mechanism with memory effects that can produce the observed scaling behavior is demonstrated. To conclude, seismic activity in Greece presents a series of significant earthquakes over the last five years. We focus on strong earthquakes, and we study the temporal evolution of aftershock sequences of them using a statistical mechanics model. The non-extensive parameter q related with the interevent times distribution varies between 1.62 and 1.71, which suggests a system with about one degree of freedom.
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Huang, Meihua, Muhammad Amin S. Murad, Onur Alp Ilhan, and Jalil Manafian. "One-, two- and three-soliton, periodic and cross-kink solutions to the (2 + 1)-D variable-coefficient KP equation." Modern Physics Letters B 34, no. 04 (January 31, 2020): 2050045. http://dx.doi.org/10.1142/s0217984920500451.
Abstract:
This paper deals with [Formula: see text]-soliton solution of the (2[Formula: see text]+[Formula: see text]1)-dimensional variable-coefficient Kadomtsev–Petviashvili equation by virtue of the Hirota bilinear operator method. The obtained solutions for solving the current equation represent some localized waves including soliton, periodic and cross-kink solutions, which have been investigated by the approach of the bilinear method. Mainly, by choosing specific parameter constraints in the [Formula: see text]-soliton solutions, all cases of the periodic and cross-kink solutions can be captured from the one-, two- and three-soliton solutions. The obtained solutions are extended with numerical simulation to analyze graphically, which results into one-, two- and three-soliton solutions and also periodic and cross-kink solutions profiles. That will be extensively used to report many attractive physical phenomena in the fields of acoustics, heat transfer, fluid dynamics, classical mechanics and so on.
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Gerolymos, G. A., D. Sénéchal, and I. Vallet. "Wall effects on pressure fluctuations in turbulent channel flow." Journal of Fluid Mechanics 720 (February 27, 2013): 15–65. http://dx.doi.org/10.1017/jfm.2012.633.
Abstract:
AbstractThe purpose of the present paper is to study the influence of wall echo on pressure fluctuations ${p}^{\prime } $, and on statistical correlations containing ${p}^{\prime } $, namely, redistribution ${\phi }_{ij} $, pressure diffusion ${ d}_{ij}^{(p)} $ and velocity pressure-gradient ${\Pi }_{ij} $. We extend the usual analysis of turbulent correlations containing pressure fluctuations in wall-bounded direct numerical simulations (Kim, J. Fluid Mech., vol. 205, 1989, pp. 421–451), separating ${p}^{\prime } $ not only into rapid ${ p}_{(r)}^{\prime } $ and slow ${ p}_{(s)}^{\prime } $ parts (Chou, Q. Appl. Maths, vol. 3, 1945, pp. 38–54), but also further into volume (${ p}_{(r; \mathfrak{V})}^{\prime } $ and ${ p}_{(s; \mathfrak{V})}^{\prime } $) and surface (wall echo, ${ p}_{(r; w)}^{\prime } $ and ${ p}_{(s; w)}^{\prime } $) terms. An algorithm, based on a Green’s function approach, is developed to compute the above splittings for various correlations containing pressure fluctuations (redistribution, pressure diffusion, velocity pressure-gradient), in fully developed turbulent plane channel flow. This exact analysis confirms previous results based on a method-of-images approximation (Manceau, Wang & Laurence, J. Fluid Mech., vol. 438, 2001, pp. 307–338) showing that, at the wall, ${ p}_{(\mathfrak{V})}^{\prime } $ and ${ p}_{(w)}^{\prime } $ are usually of the same sign and approximately equal. The above results are then used to study the contribution of each mechanism to the pressure correlations in low-Reynolds-number plane channel flow, and to discuss standard second-moment-closure modelling practices.
43
Karami, Samaneh, Ataallah Soltani Goharrizi, Bahador Abolpour, and Samira Darijani. "Numerical study of the particles segregation phenomenon in the fluidized beds." Multidiscipline Modeling in Materials and Structures 16, no. 3 (December 5, 2019): 538–56. http://dx.doi.org/10.1108/mmms-07-2019-0122.
Abstract:
Purpose The purpose of this paper is to present a computational fluid dynamic simulation for the investigation of the particles segregation phenomenon in the gas–solid fluidized beds. Design/methodology/approach These particles have the same size and different densities. The k–ε model and multiphase particle-in-cell method have been utilized for modeling the turbulent fluid flow and solid particles behaviors, respectively. The coupled equations of the velocity and pressure have been solved by using a combination of SIMPLE and PISO algorithms. After validating the simulation, different mixing indices, with different calculation bases, have been investigated, and it has been found that the Lacey mixing index, which was defined based on statistical concepts, is suitable to investigate the segregation/mixing phenomena of this bed in different conditions. Finally, the effects of parameters such as velocity, particle density ratio, jetsam concentration, and initial arrangement on the segregation/mixing behaviors of the bed have been studied. Findings The results show that the increase in the superficial gas velocity decreases the mixing index to a minimum value and then increases this index in the beds with mixed initial condition, unlike the beds with separated initial condition. Moreover, an increase in the particle density ratio increases the minimum fluidization velocity of the bed, and also the amount of segregation, and increase in the jetsam concentration increases the value of the mixing index. Originality/value A computational fluid dynamics simulation has been presented for the particles segregation phenomenon in the gas–solid fluidized beds.
44
ROSENBLATT, MARIEL, EDUARDO SERRANO, and ALEJANDRA FIGLIOLA. "AN ENTROPY BASED IN WAVELET LEADERS TO QUANTIFY THE LOCAL REGULARITY OF A SIGNAL AND ITS APPLICATION TO ANALIZE THE DOW JONES INDEX." International Journal of Wavelets, Multiresolution and Information Processing 10, no. 05 (September 2012): 1250048. http://dx.doi.org/10.1142/s0219691312500488.
Abstract:
Local regularity analysis is useful in many fields, such as financial analysis, fluid mechanics, PDE theory, signal and image processing. Different quantifiers have been proposed to measure the local regularity of a function. In this paper we present a new quantifier of local regularity of a signal: the pointwise wavelet leaders entropy. We define this new measure of regularity by combining the concept of entropy, coming from the information theory and statistical mechanics, with the wavelet leaders coefficients. Also we establish its inverse relation with one of the well-known regularity exponents, the pointwise Hölder exponent. Finally, we apply this methodology to the financial data series of the Dow Jones Industrial Average Index, registered in the period 1928–2011, in order to compare the temporal evolution of the pointwise Hölder exponent and the pointwise wavelet leaders entropy. The analysis reveals that temporal variation of these quantifiers reflects the evolution of the Dow Jones Industrial Average Index and identifies historical crisis events. We propose a new approach to analyze the local regularity variation of a signal and we apply this procedure to a financial data series, attempting to make a contribution to understand the dynamics of financial markets.
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Inc, Mustafa, Aliyu Isa Aliyu, Abdullahi Yusuf, and Dumitru Baleanu. "On the classification of conservation laws and soliton solutions of the long short-wave interaction system." Modern Physics Letters B 32, no. 18 (June 27, 2018): 1850202. http://dx.doi.org/10.1142/s0217984918502020.
Abstract:
In this paper, the classification of conservation laws (Cls) of the long short-wave interaction system (LSWS) which appears in fluid mechanics as well as plasma physics is implemented using two Cls theorems, namely, the multipliers approach and the new conservation theorem. The LSWS describes the interaction between one long longitudinal wave and one short transverse wave propagating in a generalized elastic medium. The zeroth-order multipliers and the nonlinear self-adjoint substitutions of the model are derived. Considering the fact that the new conservation theorem needs Lie point symmetries in constructing Cls, we derive the point symmetries of a system of nonlinear partial differential equations (NPDEs) acquired by transforming the model into real and imaginary components. Moreover, we derive some kink-type, bell-shaped, singular and combined soliton solutions to the model using the powerful sine-Gordon expansion method (SGEM). Some figures are presented to show the physical interpretations of the acquired results.
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Wasan, Darsh T., and Alex D. Nikolov. "Foams and Emulsions: the Importance of Structural Forces." Australian Journal of Chemistry 60, no. 9 (2007): 633. http://dx.doi.org/10.1071/ch07180.
Abstract:
We present a brief summary of the salient findings of our recent research delivered as a keynote lecture at the Australian Conference on Colloid and Interface Science held in Sydney in February 2007. We have developed a hybrid surface force apparatus (thin film capillary force balance) in conjunction with differential interference microscopy to show the phenomenon of microstructuring or stratification in thin films containing surfactant micelles, proteins, and nanoparticles separating two bubbles or droplets, as in foam and emulsion systems. The structural disjoining pressure, i.e. the structural force, arising because of the ordered microstructure formation inside thin liquid films between bubbles or drops, offers a new stabilization mechanism for foams, emulsions, and fluid-particle suspensions. In addition to the thin film approach, we also used both the Kossel diffraction and direct digitized optical imaging methods to directly observe the structure and stability of foam and emulsion systems. Our experiments were complemented by computations involving Monte Carlo simulations and the integral equation of statistical mechanics.
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Kelkar, A. S., R. L. Mahajan, and R. L. Sani. "Real-Time Physiconeural Solutions for MOCVD." Journal of Heat Transfer 118, no. 4 (November 1, 1996): 814–21. http://dx.doi.org/10.1115/1.2822575.
Abstract:
This paper presents an integrated physiconeural network approach for the modeling and optimization of a vertical MOCVD reactor. The basic concept is to utilize the solutions obtained from a physical model to build an accurate neural network (NN) model The resulting model has the attractive features of self-adaptiveness and speed of prediction and is an ideal starting tool for process optimization and control. Following this approach, a first-principles physical model for the reactor was solved numerically using the Fluid Dynamics Analysis Package (FIDAP). This transient model included property variation and thermodiffusion effects. Using software developed in house, neural networks were then trained using FIDAP simulations for combinations of process parameters determined by the statistical Design of Experiments (DOE) methodology. The outputs were the average and local deposition rates. It is shown that the trained NN model predicts the behavior of the reactor accurately. Optimum process conditions to obtain a uniform thickness of the deposited film were determined and tested using the physical model. The results demonstrate the power and robustness of NNs for obtaining fast responses to changing input conditions. A procedure for developing equipment models based on physiconeural network models is also described.
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Su, M. D., and R. Friedrich. "Investigation of Fully Developed Turbulent Flow in a Straight Duct With Large Eddy Simulation." Journal of Fluids Engineering 116, no. 4 (December 1, 1994): 677–84. http://dx.doi.org/10.1115/1.2911835.
Abstract:
Large eddy simulations have been performed in straight ducts with square cross section at a global Reynolds number of 49,000 in order to predict the complicated mean and instantaneous flow involving turbulence-driven secondary motion. Isotropic grid systems were used with spatial resolutions of 256 * 642. The secondary flow not only turned out to develop extremely slowly from its initial conditions but also to require fairly high resolution. The obtained statistical results are compared with measurements. These results show that the large eddy simulation (LES) is a powerful approach to simulate the complex turbulence flow with high Reynolds number. Streaklines of fluid particles in the duct show the secondary flow clearly. The database obtained with LES is used to examine a statistical turbulence model and describe the turbulent vortex structure in the fully developed turbulent flow in a straight duct.
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Tylicka, Marzena, Ewa Matuszczak, Joanna Kamińska, Wojciech Dębek, Beata Modzelewska, Tomasz Kleszczewski, Violetta Dymicka-Piekarska, Joanna Matowicka-Karna, Maria Karpińska, and Olga M. Koper-Lenkiewicz. "Intraoperative Peritoneal Interleukin-6 Concentration Changes in Relation to the High-Mobility Group Protein B1 and Heat Shock Protein 70 Levels in Children Undergoing Cholecystectomy." Mediators of Inflammation 2020 (July 8, 2020): 1–9. http://dx.doi.org/10.1155/2020/9613105.
Abstract:
The aim was the evaluation of IL-6 concentration in peritoneal lavage fluid of children which underwent cholecystectomy to ascertain if there is a difference in early inflammatory response depending on the type of surgical approach (open vs. laparoscopy). The analysis of high-mobility group protein B1 (HMGB1) and heat shock protein 70 (HSP70) was performed to find out if the source of IL-6 was related to tissue damage. IL-6 concentration in peritoneal lavage fluid samples, obtained at the beginning and at the end of the laparoscopic (N=23) and open cholecystectomy (N=14), was tested with a routinely used electrochemiluminescence assay. The concentrations of HMGB1 and HSP70 were analyzed with the use of an ELISA method. Statistical analysis was performed using the STATISTICA PL release 12.5 Program. The differences were assessed using the Mann-Whitney U test and Wilcoxon matched pairs test. Correlations were studied by using the Spearman correlation test. Our results demonstrated significant peritoneal lavage fluid IL-6 concentration growth measured at the end of the cholecystectomy as compared to the beginning, regardless of the type of the procedure. IL-6 growth during open cholecystectomy was greater compared to laparoscopic cholecystectomy (62.51-fold vs. 3.19-fold). IL-6 concentration did not correlate with HMGB1 and HSP70, which indicate that the significant growth of this cytokine was not related to mechanical tissue damage due to surgical procedure. A clinical significance of the study could be related to the fact that the evaluation of IL-6 concentration in peritoneal lavage fluid may be useful to assess an early local inflammatory response.
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Sharma, Bhanuday, Rakesh Kumar, Prateek Gupta, Savitha Pareek, and Ashish Singh. "On the estimation of bulk viscosity of dilute nitrogen gas using equilibrium molecular dynamics approach." Physics of Fluids 34, no. 5 (May 2022): 057104. http://dx.doi.org/10.1063/5.0088775.
Abstract:
In this work, we present a study for the estimation of bulk viscosity using the equilibrium molecular dynamics-based Green–Kubo method. We have performed a parametric study to find optimal hyper-parameters to estimate bulk viscosity using the Green–Kubo method. Although similar studies exist for shear viscosity, none has been reported so far specifically for bulk viscosity. The expected uncertainty in bulk viscosity for a given length and number of molecular dynamics trajectories used in statistical averaging is determined. The effect of system size, temperature, and pressure on bulk viscosity has also been studied. The study reveals that the decay of autocorrelation function for bulk viscosity is slower than that for shear viscosity and hence requires a longer correlation length. A novel observation has been made that the autocorrelation length required for convergence in the Green–Kubo method for both shear and bulk viscosity of dilute nitrogen gas is of the same mean collision time length units irrespective of simulation pressure. However, when the temperature is varied, the required autocorrelation length remains unaffected for shear viscosity but increases slightly with temperature for bulk viscosity. The results obtained from the Green–Kubo method are compared with experimental and numerical results from the literature with special emphasis on their comparison with the results from the nonequilibrium molecular dynamics-based continuous expansion/compression method. Although the primary focus and novelty of this work are the discussion on bulk viscosity, a similar discussion on shear viscosity has also been added.