Articoli di riviste: "Hydrodynamics"

1

Chaudhuri, A. K. "Viscous Hydrodynamic Model for Relativistic Heavy Ion Collisions". Advances in High Energy Physics 2013 (2013): 1–25. http://dx.doi.org/10.1155/2013/693180.

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Viscous hydrodynamical modeling of relativistic heavy ion collisions has been highly successful in explaining bulk of the experimental data in RHIC and LHC energy collisions. We briefly review viscous hydrodynamics modeling of high energy nuclear collisions. Basic ingredients of the modeling, the hydrodynamic equations, relaxation equations for dissipative forces, are discussed. Hydrodynamical modeling being a boundary value problem, we discuss the initial conditions, freeze-out process. We also show representative simulation results in comparison with experimental data. We also discuss the recent developments in event-by-event hydrodynamics.

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Lebed, Igor V. "Derivation of the Multimoment Hydrodynamics Equations for a Gas Mixture". Applied Physics Research 8, n. 4 (29 luglio 2016): 103. http://dx.doi.org/10.5539/apr.v8n4p103.

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<p class="1Body">The equations for pair distribution functions are used to derive the multimoment hydrodynamics equations for gas mixture. The gas mixture pair distribution functions are specified. The equations for pair functions are derived directly from the general statistical mechanics concepts. The basic property of the pair functions is established. In conformity with basic property, these functions remain unchanged in time along the trajectory of the center of inertia of a pair. The basic property of the pair distribution functions reveals the existence of an infinite number of principle hydrodynamic values. Multimoment hydrodynamics equations are constructed using 3L+4 principle hydrodynamic values, where is the number of gas mixture components. Just these principle values specify measurable moments. The measurable moments are represented by linear combination of principle and non-principle hydrodynamic values. The general structure of constructed multimoment conservation laws is identical to the structure of appropriate multimoment conservation laws in a gas of identical particles. Each of the multimoment conservation laws is divided into two separate equations. The first group of conservation equations corresponds to convective phenomena. The second group of conservation equations corresponds to dissipative phenomena. Derived multimoment hydrodynamics equations are designed for interpreting the behavior of unstable systems. As is shown previously, classic hydrodynamics equations are incapable of reproducing flows after they lose stability. That is, the solutions to the classic hydrodynamics equations do not find the direction of instability development correctly. The possibility of improvement of classic hydrodynamics equations for a gas mixture is sought on the way toward an increase in the number of principle hydrodynamic values.</p>

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Zhang, Minglu, Xiaoyu Liu e Ying Tian. "Modeling Analysis and Simulation of Viscous Hydrodynamic Model of Single-DOF Manipulator". Journal of Marine Science and Engineering 7, n. 8 (9 agosto 2019): 261. http://dx.doi.org/10.3390/jmse7080261.

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Hydrodynamic modeling is the basis of the precise control research of underwater manipulators. Viscous hydrodynamics, an important part of the hydrodynamic model, directly affects the accuracy of the dynamic model and the control model of the manipulator. Considering the limited research on viscous hydrodynamics of underwater manipulators and the difficulty in measuring viscous hydrodynamic coefficients, the viscous hydrodynamic model in the form of Taylor expansion is analyzed and established. Through carrying out simulation calculations, curve fitting and regression analysis, positional derivatives, rotational derivatives, and coupling derivatives in the viscous hydrodynamic model, are determined. This model provides a crucial theoretical foundation and reference data for subsequent related research.

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Liu, Wenshuai. "Evolution of circumbinary accretion disk around supermassive binary black hole: post-Newtonian hydrodynamics versus Newtonian hydrodynamics". Monthly Notices of the Royal Astronomical Society 504, n. 1 (15 aprile 2021): 1473–81. http://dx.doi.org/10.1093/mnras/stab1022.

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ABSTRACT We study the evolution of accretion disk around a supermassive binary black hole with equal mass using non-relativistic hydrodynamical simulations performed with FARGO3D. Compared with previous studies with the Newtonian hydrodynamics, here, we adopt the post-Newtonian (PN) hydrodynamics using the near zone metric of the binary black hole. In contrast to the Newtonian investigation, we find that there is a dramatic difference in the PN regime, gap formed by the circumbinary accretion disk around the binary with equal mass is wider with the PN hydrodynamics than that with the Newtonian hydrodynamics and is independent of disk viscosity given that hydrodynamical simulations are run for about the same factor times the viscous timescale associated with different viscosities. This may present unique observable signatures of the continuum emission in such binary-disk system.

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Freiberger, Fabian, Jens Budde, Eda Ateş, Michael Schlüter, Ralf Pörtner e Johannes Möller. "New Insights from Locally Resolved Hydrodynamics in Stirred Cell Culture Reactors". Processes 10, n. 1 (5 gennaio 2022): 107. http://dx.doi.org/10.3390/pr10010107.

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The link between hydrodynamics and biological process behavior of antibody-producing mammalian cell cultures is still not fully understood. Common methods to describe dependencies refer mostly to averaged hydrodynamic parameters obtained for individual cultivation systems. In this study, cellular effects and locally resolved hydrodynamics were investigated for impellers with different spatial hydrodynamics. Therefore, the hydrodynamics, mainly flow velocity, shear rate and power input, in a single- and a three-impeller bioreactor setup were analyzed by means of CFD simulations, and cultivation experiments with antibody-producing Chinese hamster ovary (CHO) cells were performed at various agitation rates in both reactor setups. Within the three-impeller bioreactor setup, cells could be cultivated successfully at much higher agitation rates as in the single-impeller bioreactor, probably due to a more uniform flow pattern. It could be shown that this different behavior cannot be linked to parameters commonly used to describe shear effects on cells such as the mean energy dissipation rate or the Kolmogorov length scale, even if this concept is extended by locally resolved hydrodynamic parameters. Alternatively, the hydrodynamic heterogeneity was statistically quantified by means of variance coefficients of the hydrodynamic parameters fluid velocity, shear rate, and energy dissipation rate. The calculated variance coefficients of all hydrodynamic parameters were higher in the setup with three impellers than in the single impeller setup, which might explain the rather stable process behavior in multiple impeller systems due to the reduced hydrodynamic heterogeneity. Such comprehensive insights lead to a deeper understanding of the bioprocess.

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Stevens, Ian R. "Colliding stellar winds: X-ray emission and instabilities". Symposium - International Astronomical Union 163 (1995): 486–94. http://dx.doi.org/10.1017/s0074180900202519.

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Colliding stellar winds are an important part of early-type binaries. In this paper I discuss the phenomenon, concentrating mainly on the basic hydrodynamics of colliding winds, and the physics of X-ray emission. The following topics are covered:1) Basic physics: The basic characteristics of the shock-produced thermal X-ray emission, and discuss general trends of X-ray emission from colliding wind binaries (CWBs).2) Hydrodynamic simulations: Recent calculations have found that the interface in colliding winds is usually dynamically unstable, with three distinct instabilities.3) Gamma Velorum: recent ROSAT observations give much insight into colliding winds. I discuss recent hydrodynamic calculations pertaining to these observations.4) Radiation Hydrodynamics in CWBs: Recent calculations have included the effects of both radiation fields on the wind hydrodynamics in colliding wind systems.

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Jaiswal, Amaresh, e Victor Roy. "Relativistic Hydrodynamics in Heavy-Ion Collisions: General Aspects and Recent Developments". Advances in High Energy Physics 2016 (2016): 1–39. http://dx.doi.org/10.1155/2016/9623034.

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Relativistic hydrodynamics has been quite successful in explaining the collective behaviour of the QCD matter produced in high energy heavy-ion collisions at RHIC and LHC. We briefly review the latest developments in the hydrodynamical modeling of relativistic heavy-ion collisions. Essential ingredients of the model such as the hydrodynamic evolution equations, dissipation, initial conditions, equation of state, and freeze-out process are reviewed. We discuss observable quantities such as particle spectra and anisotropic flow and effect of viscosity on these observables. Recent developments such as event-by-event fluctuations, flow in small systems (proton-proton and proton-nucleus collisions), flow in ultracentral collisions, longitudinal fluctuations, and correlations and flow in intense magnetic field are also discussed.

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Fletcher, Thomas, John Altringham, Jeffrey Peakall, Paul Wignall e Robert Dorrell. "Hydrodynamics of fossil fishes". Proceedings of the Royal Society B: Biological Sciences 281, n. 1788 (7 agosto 2014): 20140703. http://dx.doi.org/10.1098/rspb.2014.0703.

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From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall drag while serving a protective function. Here, we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms.

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9

Kodama, T., R. Donangelo e M. W. Guidry. "Inclusion of Retardation Effects in Hydrodynamical Calculations". International Journal of Modern Physics C 09, n. 05 (luglio 1998): 745–58. http://dx.doi.org/10.1142/s0129183198000650.

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In numerical large-scale hydrodynamics calculations, such as the description of a supernova explosion, instantaneous thermalization of the fluid matter is assumed independently of the size of the volume element used in the calculation. One expects, however, the appearance of transient processes such as convection currents, vortices, and other collective motion on smaller and smaller scales, which can delay equilibration. To account for these effects in a simple one-dimensional hydrodynamical calculation, we introduce retardation in the hydrodynamic equations and show that, when strong shocks are present, such effects may have considerable influence on the evolution of the system.

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Zeng, Bowen, Zhong-Ke Ding, Hui Pan, Nannan Luo, Jiang Zeng, Li-Ming Tang e Ke-Qiu Chen. "Strong strain-dependent phonon hydrodynamic window in bilayer graphene". Applied Physics Letters 121, n. 25 (19 dicembre 2022): 252202. http://dx.doi.org/10.1063/5.0129590.

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Phonon hydrodynamics, a collective motion of phonons, has recently attracted renewed attention since its temperature window has been greatly extended in layered materials. The exploration of phonon hydrodynamics bears importance in understanding phonon collective behavior, and its window is crucial for determining the phonon transport regime and engineering the heat transport. Thus, strategies for continuous tuning of the hydrodynamic window are needed, but it remains a challenge. In this work, we demonstrate that the phonon hydrodynamic window in bilayer graphene can be strongly altered by the strain based on theoretical calculations. In particular, the phonon hydrodynamics can be observed at 60 K in unstrained bilayer graphene, while only 0.25% strain can reduce this temperature to 28 K. This strong strain dependence not only provides an efficient way of modulating the phonon collective behavior but also renders a possibility of strain-induced transition of phonon transport regime.

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Murante, G., S. Borgani, R. Brunino e S. H. Cha. "Hydrodynamic simulations with the Godunov smoothed particle hydrodynamics". Monthly Notices of the Royal Astronomical Society 417, n. 1 (13 settembre 2011): 136–53. http://dx.doi.org/10.1111/j.1365-2966.2011.19021.x.

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12

Kholpanov, L. P. "Hydrodynamics and mass exchange in active hydrodynamic regimes". Chemical and Petroleum Engineering 33, n. 2 (marzo 1997): 109–19. http://dx.doi.org/10.1007/bf02396028.

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NAKAYAMA, YU. "INTRINSIC AMBIGUITY IN SECOND-ORDER VISCOSITY PARAMETERS IN RELATIVISTIC HYDRODYNAMICS". International Journal of Modern Physics A 27, n. 22 (30 agosto 2012): 1250125. http://dx.doi.org/10.1142/s0217751x12501254.

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We show that relativistic hydrodynamics in Minkowski space–time has intrinsic ambiguity in second-order viscosity parameters in the Landau–Lifshitz frame. This stems from the possibility of improvements of energy–momentum tensor. There exist at least two viscosity parameters which can be removed by using this ambiguity in scale invariant hydrodynamics in (1+3) dimension, and seemingly nonconformal hydrodynamic theories can be hiddenly conformal invariant.

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STEVENSON, P. M. "HYDRODYNAMICS OF THE VACUUM". International Journal of Modern Physics A 21, n. 13n14 (10 giugno 2006): 2877–903. http://dx.doi.org/10.1142/s0217751x06028527.

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Hydrodynamics is the appropriate "effective theory" for describing any fluid medium at sufficiently long length scales. This paper treats the vacuum as such a medium and derives the corresponding hydrodynamic equations. Unlike a normal medium the vacuum has no linear sound-wave regime; disturbances always "propagate" nonlinearly. For an "empty vacuum" the hydrodynamic equations are familiar ones (shallow water-wave equations) and they describe an experimentally observed phenomenon — the spreading of a clump of zero-temperature atoms into empty space. The "Higgs vacuum" case is much stranger; pressure and energy density, and hence time and space, exchange roles. The speed of sound is formally infinite, rather than zero as in the empty vacuum. Higher-derivative corrections to the vacuum hydrodynamic equations are also considered. In the empty-vacuum case the corrections are of quantum origin and the post-hydrodynamic description corresponds to the Gross–Pitaevskii equation. We conjecture the form of the post-hydrodynamic corrections in the Higgs case. In the (1+1)-dimensional case the equations possess remarkable "soliton" solutions and appear to constitute a new exactly integrable system.

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Li, Ao, Wanshun Zhang, Xiao Zhang, Gang Chen, Xin Liu, Anna Jiang, Feng Zhou e Hong Peng. "A Deep U-Net-ConvLSTM Framework with Hydrodynamic Model for Basin-Scale Hydrodynamic Prediction". Water 16, n. 5 (20 febbraio 2024): 625. http://dx.doi.org/10.3390/w16050625.

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Traditional hydrodynamic models face the significant challenge of balancing the demands of long prediction spans and precise boundary conditions, large computational areas, and low computational costs when attempting to rapidly and accurately predict the nonlinear spatial and temporal characteristics of fluids at the basin scale. To tackle this obstacle, this study constructed a novel deep learning framework with a hydrodynamic model for the rapid spatiotemporal prediction of hydrodynamics at the basin scale, named U-Net-ConvLSTM. A validated high-fidelity hydrodynamic mechanistic model was utilized to build a 20-year hydrodynamic indicator dataset of the middle and lower reaches of the Han River for the training and validation of U-Net-ConvLSTM. The findings indicate that the R2 value of the model surpassed 0.99 when comparing the single-step prediction results with the target values. Additionally, the required computing time fell by 62.08% compared with the hydrodynamic model. The ablation tests demonstrate that the U-Net-ConvLSTM framework outperforms other frameworks in terms of accuracy for basin-scale hydrodynamic prediction. In the multi-step-ahead prediction scenarios, the prediction interval increased from 1 day to 5 days, while consistently maintaining an R2 value above 0.7, which demonstrates the effectiveness of the model in the missing boundary conditions scenario. In summary, the U-Net-ConvLSTM framework is capable of making precise spatiotemporal predictions in hydrodynamics, which may be considered a high-performance computational solution for predicting hydrodynamics at the basin scale.

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Bal'chugov, Aleksey, e Artem Badenikov. "HYDRODYNAMICS OF A ROTARY DISC ABSORBER". Scientific Papers Collection of the Angarsk State Technical University 2023, n. 1 (5 luglio 2023): 45–49. http://dx.doi.org/10.36629/2686-7788-2023-1-45-49.

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The hydrodynamics of a new rotary mass transfer apparatus is considered. It is shown that the most important hydrodynamic characteristics of the apparatus operation are: the average drop diameter, the initial drop velocity, the drop rise time, the drop rise height

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Sunol, Alp M., e Roseanna N. Zia. "Confined Brownian suspensions: Equilibrium diffusion, thermodynamics, and rheology". Journal of Rheology 67, n. 2 (marzo 2023): 433–60. http://dx.doi.org/10.1122/8.0000520.

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We examine the impact of confinement on the structure, dynamics, and rheology of spherically confined macromolecular suspensions, with a focus on the role played by entropic forces, by comparing the limits of strong hydrodynamics and no hydrodynamics. We present novel measurements of the osmotic pressure, intrinsic viscosity, and long-time self-diffusivity in spherical confinement and find confinement induces strong structural correlations and restrictions on configurational entropy that drive up osmotic pressure and viscosity and drive down self-diffusion. Even in the absence of hydrodynamics, confinement produces distinct short-time and long-time self-diffusion regimes. This finding revises the previous understanding that short-time self-diffusion is a purely hydrodynamic quantity. The entropic short-time self-diffusion is proportional to an entropic mobility, a direct analog to the hydrodynamic mobility. A caging plateau following the short-time regime is stronger and more durable without hydrodynamics, and entropic drift—a gradient in volume fraction—drives particles out of their cages. The distinct long-time regime emerges when an entropic mobility gradient arising from heterogeneous distribution of particle volume drives particles out of local cages. We conclude that entropic mobility gradients produce a distinct long-time dynamical regime in confinement and that hydrodynamic interactions weaken this effect. From a statistical physics perspective, confinement restricts configurational entropy, driving up confined osmotic pressure, viscosity, and (inverse) long-time dynamics as confinement tightens. We support this claim by rescaling the volume fraction as the distance from confinement-dependent maximum packing, which collapses the data for each rheological measure onto a single curve.

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Liping, Wang, e Zheng Binghui. "Prediction of chlorophyll-a in the Daning River of Three Gorges Reservoir by principal component scores in multiple linear regression models". Water Science and Technology 67, n. 5 (1 marzo 2013): 1150–58. http://dx.doi.org/10.2166/wst.2013.679.

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After the impoundment of the Three Gorges Reservoir (TGR) since 2003, eutrophication has occurred and has become severe in Daning River. To predict chlorophyll-a (Chl-a) levels, the relationships between Chl-a and 11/13 routine monitoring data on water quality and hydrodynamics in Daning River were studied by principal component scores in the multiple linear regression model (principal component regression (PCR) model). In order to determine the hydrodynamic effect on simulated accuracy, two 0-day ahead prediction models were established: model A without hydrodynamic factors as variables, and model B with hydrodynamic factors (surface water velocity and water residence time) as variables. Based on the results of correlation analysis, score 1 and 2 with significant loads of phosphorus and nitrogen nutrients were omitted in developing model A (R2 = 0.355); while score 2 with significant loads of nitrogen was omitted in developing model B (R2 = 0.777). The results of validation using a new dataset showed that model B achieved a better fitted relationship between the predicted and observed values of Chl-a. It indicated hydrodynamics play an important role in limiting algal growth. The results suggested that a PCR model incorporating hydrodynamics processes has been suitable for the Chl-a concentration simulation and algal blooming prediction in Daning River of TGR.

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Savitsky, A., M. Radkevich, A. Salokhiddinov, O. Ashirova, T. Khankelov, K. Shipilova, M. Abdukadirova, A. Gapirov e R. Razzakov. "A New Approach to the Use of Non-Primitive Variables in the Mechanics of Continuous Media". Emerging Science Journal 8, n. 2 (1 aprile 2024): 700–715. http://dx.doi.org/10.28991/esj-2024-08-02-021.

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The problem of an approximate solution to hydrodynamic problems is the consideration of pressure. To exclude it from the equations, the transition to “non-primitive variables” (vortex and velocity vector divergence) is made. In this case, there are difficulties in the algorithmization of new equations for solving the inverse problem of hydrodynamics and a lot of internal iterative calculations. The object of this study includes equations in “non-primitive” variables. The research methods are based on the transformation without simplifications and assumptions of hydrodynamic equations into a form containing “non-primitive” variables and the demonstration of the possibilities of solving the equations. The GAMS programming language was used for approximate solutions for the first time. The aim of this paper is to demonstrate the possibility of solving the full equations in “non-primitive” variables for various conditions. The results showed the possibility of considering the compressibility of the medium when solving the inverse problem of hydrodynamics; the identity of solutions of the proposed system of equations and equations using the potential; and the possibility of using optimizing programming languages for hydrodynamics problems. The scientific novelty of this research consists of solving the full equations of hydrodynamics with the use of “non-primitive” variables but without the use of the current function. Doi: 10.28991/ESJ-2024-08-02-021 Full Text: PDF

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Markesteijn, Anton, Sergey Karabasov, Arturs Scukins, Dmitry Nerukh, Vyacheslav Glotov e Vasily Goloviznin. "Concurrent multiscale modelling of atomistic and hydrodynamic processes in liquids". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, n. 2021 (6 agosto 2014): 20130379. http://dx.doi.org/10.1098/rsta.2013.0379.

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Fluctuations of liquids at the scales where the hydrodynamic and atomistic descriptions overlap are considered. The importance of these fluctuations for atomistic motions is discussed and examples of their accurate modelling with a multi-space–time-scale fluctuating hydrodynamics scheme are provided. To resolve microscopic details of liquid systems, including biomolecular solutions, together with macroscopic fluctuations in space–time, a novel hybrid atomistic–fluctuating hydrodynamics approach is introduced. For a smooth transition between the atomistic and continuum representations, an analogy with two-phase hydrodynamics is used that leads to a strict preservation of macroscopic mass and momentum conservation laws. Examples of numerical implementation of the new hybrid approach for the multiscale simulation of liquid argon in equilibrium conditions are provided.

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GALE, CHARLES, SANGYONG JEON e BJÖRN SCHENKE. "HYDRODYNAMIC MODELING OF HEAVY-ION COLLISIONS". International Journal of Modern Physics A 28, n. 11 (25 aprile 2013): 1340011. http://dx.doi.org/10.1142/s0217751x13400113.

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We review progress in the hydrodynamic description of heavy-ion collisions, focusing on recent developments in modeling the fluctuating initial state and event-by-event viscous hydrodynamic simulations. We discuss how hydrodynamics can be used to extract information on fundamental properties of quantum chromodynamics from experimental data, and review successes and challenges of the hydrodynamic framework.

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Buchel, Alex. "hydrodynamics". Nuclear Physics B 708, n. 1-3 (febbraio 2005): 451–66. http://dx.doi.org/10.1016/j.nuclphysb.2004.11.039.

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Ivanov, A. Yu, P. A. Andreev e L. S. Kuz'menkov. "Balance equations in semi-relativistic quantum hydrodynamics". International Journal of Modern Physics B 28, n. 21 (24 giugno 2014): 1450132. http://dx.doi.org/10.1142/s021797921450132x.

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Method of the quantum hydrodynamics has been applied in quantum plasmas studies. As the first step in our consideration, derivation of classical semi-relativistic (i.e., described by the Darwin Lagrangian on microscopic level) hydrodynamical equations is given after a brief review of method development. It provides better distinguishing between classic and quantum semi-relativistic effects. Derivation of the classical equations is interesting since it is made by a natural, but not very widespread method. This derivation contains explicit averaging of the microscopic dynamics. Derivation of corresponding quantum hydrodynamic equations is presented further. Equations are obtained in the five-momentum approximation including the continuity equation, Euler and energy balance equations. It is shown that relativistic corrections lead to presence of new quantum terms in expressions for a force field, a work field etc. The semi-relativistic generalization of the quantum Bohm potential is obtained. Quantum part of the energy current, which is an analog of the quantum Bohm potential for the energy evolution equation, is derived. The Langmuir wave dispersion in semi-relativistic quantum plasmas, corresponding to the Darwin Lagrangian, is also considered to demonstrate contribution of semi-relativistic effects on basic plasma phenomenon.

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Bobylev, A. V. "Boltzmann equation and hydrodynamics beyond Navier–Stokes". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, n. 2118 (19 marzo 2018): 20170227. http://dx.doi.org/10.1098/rsta.2017.0227.

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We consider in this paper the problem of derivation and regularization of higher (in Knudsen number) equations of hydrodynamics. The author’s approach based on successive changes of hydrodynamic variables is presented in more detail for the Burnett level. The complete theory is briefly discussed for the linearized Boltzmann equation. It is shown that the best results in this case can be obtained by using the ‘diagonal’ equations of hydrodynamics. Rigorous estimates of accuracy of the Navier–Stokes and Burnett approximations are also presented. This article is part of the theme issue ‘Hilbert’s sixth problem’.

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Doyon, Benjamin, e Jason Myers. "Fluctuations in Ballistic Transport from Euler Hydrodynamics". Annales Henri Poincaré 21, n. 1 (15 novembre 2019): 255–302. http://dx.doi.org/10.1007/s00023-019-00860-w.

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AbstractWe propose a general formalism, within large-deviation theory, giving access to the exact statistics of fluctuations of ballistically transported conserved quantities in homogeneous, stationary states. The formalism is expected to apply to any system with an Euler hydrodynamic description, classical or quantum, integrable or not, in or out of equilibrium. We express the exact scaled cumulant generating function (or full counting statistics) for any (quasi-)local conserved quantity in terms of the flux Jacobian. We show that the “extended fluctuation relations” of Bernard and Doyon follow from the linearity of the hydrodynamic equations, forming a marker of “freeness” much like the absence of hydrodynamic diffusion does. We show how an extension of the formalism gives exact exponential behaviours of spatio-temporal two-point functions of twist fields, with applications to order-parameter dynamical correlations in arbitrary homogeneous, stationary state. We explain in what situations the large-deviation principle at the basis of the results fail, and discuss how this connects with nonlinear fluctuating hydrodynamics. Applying the formalism to conformal hydrodynamics, we evaluate the exact cumulants of energy transport in quantum critical systems of arbitrary dimension at low but nonzero temperatures, observing a phase transition for Lorentz boosts at the sound velocity.

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Xue, Gang, Fagang Bai, Zhitong Li e Yanjun Liu. "Experiment for Effect of Attack Angle and Environmental Condition on Hydrodynamics of Near-Surface Swimming Fish-Like Robot". Applied Bionics and Biomechanics 2023 (1 aprile 2023): 1–16. http://dx.doi.org/10.1155/2023/4377779.

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Fish-like robot is a special autonomous underwater vehicle with broad application prospects. Some previous studies concentrated on the hydrodynamics of free-swimming fish-like robots. But the hydrodynamic performance of fish-like robot swimming with a tilt angle in constrained space has not been well studied, and the influence of environmental wave and current on its is also still unclear. In this paper, the experiment devices, including a physical fish-like robot, a hydrodynamics measurement platform, and a six-axis force sensor, are used to study the effect of attack angle and environmental condition on the hydrodynamics of near-surface swimming fish-like robot. Nine attack angles, five oscillating amplitudes, and three environmental conditions are analyzed in the experiments. It shows that thrust force decreases when caudal fin passes above water surface, but the increased difference between gravity force and buoyancy force will compensate the decreased force generated by caudal fin when fish-like robot swims with certain dive angle. The extra reaction force generated by solid bottom boundary will promote the thrust force and vertical force. The surface water wave condition or surface water current condition also has obvious effects on hydrodynamic performance. This paper provides a new perspective to the research on the hydrodynamic performance of fish-like robot and will do favor in the development of fish-like robot.

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Zhang, Yu, Lei Wang e Hui Fang Liu. "Solar Underwater Glider Robot of Viscous Hydrodynamic Numerical Calculation". Applied Mechanics and Materials 487 (gennaio 2014): 653–56. http://dx.doi.org/10.4028/www.scientific.net/amm.487.653.

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Hydrodynamic coefficients of solar underwater glider robot are one of the important indicators to measure its maneuverability. Based on solar underwater glider robot, using ANSYS CFX software simulate analysis, and through the MATLAB data fitting to body hydrodynamic coefficients. Drawing hydrodynamic coefficient curves for the robot is the critical study of underwater robot hydrodynamics, its shape optimization for subsequent theoretical data is important.

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Jayaratne, Ravindra, Mara Nicholas, Behnaz Ghodoosipour, Sophie Mugnaini, Ioan Nistor e Tomoya Shibayama. "TSUNAMI-INDUCED HYDRODYNAMICS AND SCOUR AROUND STRUCTURES". Coastal Engineering Proceedings, n. 36 (30 dicembre 2018): 5. http://dx.doi.org/10.9753/icce.v36.currents.5.

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The complex hydrodynamics during a tsunami event can significantly affect the structural integrity of buildings. The resulting hydrodynamic forces are influenced by various fluid parameters such as the fluid density, flow velocity and depth, as well as by the structureâ€™s geometry. Hydrodynamic forces induced by tsunami pressures and velocities are particularly important, as they occur usually around a coastal defence structure or a building and as a result, they affect the structural integrity of the structure (Chinnarasri et al, 2013). The 2011 Japan post-tsunami field survey of Chock et al. (2013) indicated that lateral pressures, uplift pressures and surge flow from the tsunami produced hydrodynamic forces responsible for the destruction of many structures along the Tohoku coastline. The associated hydrodynamic parameters of a tsunami such as pressures and velocities also influence the tsunami-induced scour around buildings. Nicholas et al. (2016) stated that the tsunami-induced hydrodynamic velocity was a crucial factor in producing soil-scour around building structures.

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Liu, Yanyan, Rongrong Shan, Guowei Chen e Li Liu. "Linking flow velocity-regulated EPS production with early-stage biofilm formation in drinking water distribution systems". Water Supply 20, n. 4 (16 marzo 2020): 1253–63. http://dx.doi.org/10.2166/ws.2020.039.

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Abstract Hydrodynamics impacts interactions between microbes and their micro-habitats in aqueous systems, thus the study of hydrodynamics is key to understanding the formation and dynamics of biofilms. Yet mechanisms of how microbial responses to hydrodynamics regulate biofilm formation in drinking water distribution systems (DWDS) are underappreciated. Here, we investigated the linkage between early-stage biofilm formation and flow velocity fluctuations in a model DWDS. Results showed that an intermediate velocity (1.0 m/s) enhanced biofilm formation, with the highest biofilm/total cells ratio of 96.91% ± 2.26%. Moreover, the intermediate velocity promoted extracellular polymeric substances (EPS) release, accompanied with lowered zeta potential and elevated hydrophobicity of suspended cells, which could be responsible for surface aggregation. Shifts in biofilm community were observed along with hydrodynamics fluctuations. Intermediate velocity (1.0 m/s) stimulated the dominance of Proteobacteria (78.16%) along with the genus predominance of Pseudomonas, known to secrete large amounts of EPS favoring biofilm formation. Overall, this study provides new understanding of biofilm formation responding to hydrodynamic fluctuations in DWDS.

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30

Lee, Minhyung. "Incorporation of Magneto-Hydrodynamics into Axisymmetric Hydrodynamics Code". Transactions of the Korean Society of Mechanical Engineers - B 46, n. 5 (31 maggio 2022): 231–36. http://dx.doi.org/10.3795/ksme-b.2022.46.5.231.

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31

Krainov, A. V., E. N. Pashkov e P. G. Yurovskiy. "Heat and Mass Transfer in Viscous Fluid Flows in Open Cavities with Moving Boundaries under Cooling the External Contour". Advanced Materials Research 1040 (settembre 2014): 638–41. http://dx.doi.org/10.4028/www.scientific.net/amr.1040.638.

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Abstract (sommario):

The paper presents the numerical research heat mass transfer and hydrodynamics in the motion of viscous fluid in the rectangular cavity in the consideration of the crystallization process. The hydrodynamic Figure of viscous fluid and temperature fields obtained. The impact of hydrodynamic parameters and geometrical characteristics for forming crystallization front is studied.

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32

Steffen, Matthias. "Radiative hydrodynamics models of stellar convection". Proceedings of the International Astronomical Union 2, S239 (agosto 2006): 36–43. http://dx.doi.org/10.1017/s1743921307000087.

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Abstract (sommario):

AbstractIn the quest for a better theoretical understanding of the dynamical processes operating in stellar envelopes, increasingly more realistic hydrodynamical models of stellar convection have been developed over the last 25 years. Based on 3D state-of-the-art simulations performed recently with the radiation hydrodynamics code CO5BOLD, we review the present status of hydrodynamical modeling of stellar surface convection and demonstrate the basic differences between 3D hydrodynamical models and 1D ‘classical’ hydrostatic atmospheres where convection is treated by the mixing-length theory. We briefly discuss some of the many possible applications across the Hertzsprung-Russell diagram, including spectroscopic abundance determinations using 3D stellar atmospheres, particularly with regard to the much debated question of the solar oxygen abundance.

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33

Nakayama, Yu. "Anomalous hydrodynamics with dyonic charge". International Journal of Modern Physics A 36, n. 18 (16 giugno 2021): 2150133. http://dx.doi.org/10.1142/s0217751x21501335.

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Abstract (sommario):

In this paper, we study anomalous hydrodynamics with a dyonic charge. We show that the local second law of thermodynamics constrains the structure of the anomaly in addition to the structure of the hydrodynamic constitutive equations. In particular, we show that not only the usual [Formula: see text] term but also [Formula: see text] term should be present in the anomaly with a specific coefficient for the local entropy production to be positive definite.

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34

Dhia, Hamed Ben. "Thermal regime and hydrodynamics in Tunisia and Algeria". GEOPHYSICS 56, n. 7 (luglio 1991): 1093–102. http://dx.doi.org/10.1190/1.1443121.

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Abstract (sommario):

The thermal regime of Algeria and Tunisia and its relation to hydrodynamics is studied by means of available geological and geothermal, and petroleum data. Heat flow densities in the area range from [Formula: see text] to [Formula: see text]. Several Paleozoic to Tertiary aquifers have been identified, together with potential recharge and discharge areas. The area is a transition zone between the African and European plates. The more tectonically active northern Alpine domain does not exhibit an obvious geothermal trend, and high heat flow anomalies that occur there may be related to structure rather than hydrodynamics. The more stable southern Saharan tectonic domain, with background heat flow of approximately [Formula: see text], exhibits anomalous zones correlated to the hydrodynamic regime with low values in recharge areas (Algerian Tinrhert and High Plateaux) and values in discharge areas (Tunisian Jeffara and Algerian Tademait). The hydrodynamic perturbation to the normal heat flow is estimated to be as great as [Formula: see text] in recharge and discharge zones.

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35

Gorev, V. N., e A. I. Sokolovsky. "Non-dissipative hydrodynamic equations based on a nonlocal collision integral". Journal of Physics and Electronics 26, n. 1 (3 dicembre 2018): 11–18. http://dx.doi.org/10.15421/331802.

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Abstract (sommario):

We consider a slightly non-uniform one-component gas with weak potential interaction. The basis of the investigation is the known kinetic equation in the case of small interaction which is truncated up to the second order of smallness. This equation contains a nonlocal collision integral of the second order in small interaction. In this paper we consider the hydrodynamic stage of the system evolution, and, in contrast to the standard hydrodynamics, we take into account the non-locality of the collision integral. We propose the following set of the reduced description parameters which are the densities of the conserved quantities: the particle number density, the momentum density, and the total energy density. It should be stressed that in contrast to the standard hydrodynamics, the kinetic energy is not conserved, and only the total system energy is conserved if the nonlocal collision integral is used. Definitions of the system velocity and temperature are proposed; it should be stressed that the proposed temperature definition is based on the total system energy rather than on the kinetic one. The hydrodynamics in the leading order in small gradients is investigated, and it is shown that the system one-particle distribution function in the leading-in-gradients order coincides with the Maxwellian one. Particle number density, velocity and temperature time evolution equations (hydrodynamic equations) are derived in the non-dissipative case. The leading-in-interaction orders of the obtained equations coincide with the corresponding equations in the framework of the standard hydrodynamics. The corrections of the first and second order in small interaction are also obtained.

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36

Atamanyuk, Volodymyr, Zoriana Gnativ, Diana Kindzera, Dauren Janabayev, Alisher Khusanov e Botagoz Kaldybaeva. "Hydrodynamics of Cotton Filtration Drying". Chemistry & Chemical Technology 14, n. 3 (22 settembre 2020): 426–32. http://dx.doi.org/10.23939/chcht14.03.426.

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37

Sarbassov, Yerbol, Azd Zayoud, Pinakeswar Mahanta, Sai Gu, Panneerselvam Ranganathan e Ujjwal Saha. "Hydrodynamic experiments on a small-scale circulating fluidized bed reactor at elevated operating pressure, and under an O2/CO2 environment". Thermal Science 21, n. 2 (2017): 1093–104. http://dx.doi.org/10.2298/tsci150921068s.

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Abstract (sommario):

Pressurized circulating fluidized bed technology is a potentially promising development for clean coal technologies. The current work explores the hydrodynamics of a small-scale circulating fluidized bed at elevated operating pressures ranging from 0.10 to 0.25 MPa. The initial experiments were performed at atmospheric pressure with air and O2/CO2 environments as the fluidization gas to simulate the hydrodynamics in a circulating fluidized bed. A comparison between the effects of air and O2/CO2 mixtures on the hydrodynamics was outlined in this paper for particles of 160 ?m diameter. A small but distinct effect on axial void-age was observed due to the change in gas density in the dense zone of the bed at lower gas velocity, while only minimal differences were noticed at higher gas velocities. The hydrodynamic parameters such as pressure drop and axial voidage profile along the height were reported at two different bed inventories (0.5 and 0.75 kg) for three mean particle sizes of 160, 302, and 427 ?m and three superficial gas velocities. It was observed that the operating pressure had a significant effect on the hydrodynamic parameters of bed pressure drop and axial bed void-age profiles. The effect of solids loading resulted in an exponential change in pressure drop profile at atmospheric pressure as well as at elevated pressure. The experimental results on hydrodynamic parameters are in reasonable agreement with published observations in the literature.

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38

Bouchette, Frédéric, Mathieu Schuster, Jean-François Ghienne, Cléa Denamiel, Claude Roquin, Abderamane Moussa, Patrick Marsaleix e Philippe Duringer. "Hydrodynamics in Holocene Lake Mega-Chad". Quaternary Research 73, n. 2 (marzo 2010): 226–36. http://dx.doi.org/10.1016/j.yqres.2009.10.010.

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Abstract (sommario):

Holocene Lake Mega-Chad (LMC) was the largest late Quaternary water-body in Africa. The development of this giant paleo-lake is related to a northward shift of the isohyetes interpreted as evidence for an enhanced Monsoon (African Humid Period). Numerous preserved coastal features have been described all around the LMC shore. Such features reveal the main paleo-hydrodynamical tendencies. In the context of a closed water-body like LMC, hydrodynamics are forced mainly by winds. We use a three-dimensional numerical model (SYMPHONIE) to simulate the mean hydrodynamics in LMC under both Harmattan-like (northeasterly trade winds) and Monsoon-like (southwesterly winds) forcings. The northern part of LMC displays coastal features, such as sand spits, that are consistent with the simulations forced by Harmattan-like winds. Geomorphic features related to Monsoon-driven hydrodynamics are not clearly expressed. They could have developed during the early stage of LMC but subsequently reworked. At the time of sand-spit building, Harmattan-like driven hydrodynamics prevailed and related coastal features were preferentially preserved in the sedimentary record.

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39

Khamraeva, L. S., L. Yu Bobokha e N. Sh Akhmedova. "Eye hydrodynamics in children subject to total intravenous anesthesia". Russian Ophthalmological Journal 12, n. 1 (16 marzo 2019): 70–74. http://dx.doi.org/10.21516/2072-0076-2019-12-1-70-74.

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Purpose: to study eye hydrodynamics in children subjected to total intravenous anesthesia during ophthalmic operations. Materials and methods. 50 children (100 eyes) aged 15 days to 14 years were examined. 21 children showed impaired hydrodynamics while the remaining 29 had no hydrodynamic disorders. All patients received combined endotracheal anesthesia for ophthalmic operations.Results. The patients with undisturbed hydrodynamics showed a significant increase in true intraocular pressure (Po) (by 3.8 ± 0.12 mm Hg) after an injection of anesthesia with ketamine, due to a significant increase in aqueous humor production. Children with disturbed hydrodynamics, who received an antihypertensive ophthalmic drug (arutimol 0.25–0.5 %), after an injection of anesthesia with fentanyl, showed a significant Po decrease (by 3.9 ± 0.12 mm Hg) due to a significant increase of outflow facility rate (C) and a decrease in aqueous humour volume (F). The patients who received no antihypertensive therapy showed a significant decrease in Po (by 2.08 ± 0.7 mm Hg) due to a significant increase in C. In contrast, the decrease in F proved to be insignificant.Conclusion. For an objective assessment of tonographic parameters in children with impaired eye hydrodynamics who received antihypertensive therapy (arutimol 0.25–0.5 %) and anesthesized with fentanyl, we recommend that the Po indices be adjusted upwards by 3.9 ± 0.12 mm Hg, without arutimol by 2.08 ± 0.7 mm Hg, which will help in choosing the type and volume of antiglaucomatous operations. It is also necessary to take into account the increase in Po under the action of ketamine (by 3.8 ± 0.12 mm Hg) in children with undisturbed eye hydrodynamics to prevent possible intra- and postoperative complications.

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40

DUFTY, JAMES W. "KINETIC THEORY AND HYDRODYNAMICS FOR A LOW DENSITY GRANULAR GAS". Advances in Complex Systems 04, n. 04 (dicembre 2001): 397–406. http://dx.doi.org/10.1142/s0219525901000395.

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Abstract (sommario):

Many features of real granular fluids under rapid flow are exhibited as well by a system of smooth hard spheres with inelastic collisions. For such a system, it is tempting to apply standard methods of kinetic theory and hydrodynamics to calculate properties of interest. The domain of validity for such methods is a priori uncertain due to the inelasticity, but recent systematic studies continue to support the utility of kinetic theory and hydrodynamics as both qualitative and quantitative descriptions for many physical states. The basis for kinetic theory and hydrodynamic descriptions is discussed briefly for the special case of a low density gas.

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41

Al-Shyyab, Ahmad, Suleiman E. Al-Lubani, Muhammad M. Kwafha e A. F. Khadrawi. "Steady Hydrodynamics and Thermal Behaviors of Fluid Flows in Micro – Parallel Plates (Couette Flows)". Applied Mechanics and Materials 110-116 (ottobre 2011): 408–14. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.408.

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The hydrodynamics and thermal behaviors of fluid in micro - Couette flows is investigated numerically. The model that combines both the continuum approach and the possibility of slip at the boundary is adopted in the study. The Effects of Knudsen number Kn, Brinkman number and the pressure gradient on the Couette microchannel hydrodynamics and thermal behaviors are investigated. It is found that as Kn increases the slip in the hydrodynamic and thermal boundary condition increases. Also, it is found that the slip velocity and the temperature jump at the boundaries increases as the Brinkman number and the pressure gradient increases.

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42

Williams, A. N., e W. Li. "The Hydrodynamics of Floating Compound Cylinders". Journal of Offshore Mechanics and Arctic Engineering 121, n. 4 (1 novembre 1999): 213–18. http://dx.doi.org/10.1115/1.2829570.

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The hydrodynamics of a freely floating compound cylinder consisting of a surface-piercing cylindrical column resting on a larger, concentric cylindrical base are investigated theoretically. Linear wave theory and small-amplitude structural oscillations are assumed, and an eigenfunction expansion approach is used to obtain semi-analytical expressions for the hydrodynamic excitation and reaction loads on the structure. Numerical results are presented for a range of wave and structural parameters. It is found that for certain parameter combinations, negative surge/sway added mass coefficients are predicted. The numerical results for the hydrodynamic quantities obtained by the eigenfunction approach have been verified with those obtained by the linear radiation/diffraction program UHWAVE. These results have implications for the tow-out analysis of large gravity-base oil production platforms.

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43

Dias, João Miguel, Francisco Pereira, Ana Picado, Carina Lurdes Lopes, João Pedro Pinheiro, Sérgio Miguel Lopes e Paulo Gabriel Pinho. "A Comprehensive Estuarine Hydrodynamics-Salinity Study: Impact of Morphologic Changes on Ria de Aveiro (Atlantic Coast of Portugal)". Journal of Marine Science and Engineering 9, n. 2 (22 febbraio 2021): 234. http://dx.doi.org/10.3390/jmse9020234.

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Shallow coastal lagoons driven by tidal processes are extremely dynamic environments prone to continuous natural and anthropogenic pressures. The hydrodynamics of these systems deeply depends on the effect of local morphology on the tidal propagation, so their permanent evolution constantly changes tidal dependent processes. For this reason, the present work aims to review the main characteristics of Ria de Aveiro hydrodynamics, a shallow lagoon located at the Atlantic Coast of Portugal, evaluating its evolution over the last 30 years (between 1987 and 2020) and investigating the main morphological changes in its origin. For this purpose, a comparative analysis is performed to determine the main process, including the observed hydrodynamic changes: Deepening of the inlet channel or of the main lagoon channels. To achieve these goals, the authors explored a remarkable database including bathymetric, tide gauge, and salinity data from 1987 until the present. This analysis is completed by the exploitation of a hydrodynamical model (Delft3D), validated against field data. Several simulations were performed to analyse changes in tidal propagation along the lagoon channels (considering the main semi-diurnal constituent M2), tidal asymmetry, tidal currents, tidal prism, and salinity patterns. The results show that the general deepening of the lagoon observed between 1987 and 2020 led to important changes in the lagoon hydrodynamics, namely the increase/decrease of the M2 constituent amplitude/phase, as well as the increase of tidal currents and salt intrusion within the entire lagoon, with the changes being amplified towards the head of the main channels. Although the inlet deepening partially contributed to the modifications found, the results revealed that the deepening of the main lagoon channels had the most significant contribution to the changes observed during the last 30 years.

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44

Chrzanowska, Agnieszka, e Pawel T. Jochym. "Microscopic Stress Tensor of Nematic Liquid Crystal Binary Mixtures". Zeitschrift für Naturforschung A 51, n. 3 (1 marzo 1996): 147–50. http://dx.doi.org/10.1515/zna-1996-0302.

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Abstract (sommario):

A microscopic stress tensor for the binary nematic mixture of anisotropic molecules is presented. Its simple additive character is beneficial for hydrodynamics studies. We pay attention to mixtures of disc and rodlike molecules which may exhibit interesting hydrodynamic properties.

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45

Chiravalle, Vincent P. "Verification and Validation of Two Hydrodynamic Methods for Simulations of High Energy Density Physics Problems". Laser and Particle Beams 2022 (11 ottobre 2022): 1–15. http://dx.doi.org/10.1155/2022/8720064.

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Abstract (sommario):

A 3D verification and validation suite of test problems is presented and used to evaluate hydrodynamic methods within a radiation hydrodynamics code, xRAGE. These test problems exercise different levels of complexity, building towards ICF problems which in addition to hydrodynamics also include three temperature plasma physics, thermal conduction, and radiation diffusion. Among the problems in the test suite are the Kidder ball problem, the Verney shell problem, and a 5-material compression problem, which exercise different purely hydrodynamic methods implemented within xRAGE. There is excellent agreement between 2D and 3D XRAGE simulation results and between the xRAGE results and the benchmark solutions. Two 3D ICF test problems are also presented, based on an OMEGA direct drive capsule experiment and on a NIF indirect drive capsule experiment. It is demonstrated that the newer unsplit hydrodynamic method in xRAGE produces more vorticity relative to the older default method. For the indirect drive capsule, the 3D simulations are in reasonable agreement with the experimental values of ion temperature and neutron production.

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46

ZHANG, SUN, e FAN WANG. "RELATIVISTIC HYDRODYNAMICS WITH SPONTANEOUS CHIRAL SYMMETRY BREAKING". International Journal of Modern Physics E 12, n. 05 (ottobre 2003): 675–81. http://dx.doi.org/10.1142/s0218301303001491.

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Abstract (sommario):

We study the hydrodynamics of the nuclear matter of two flavors of light quarks with spontaneous chiral symmetry breaking based on the Poisson bracket method. The effects of mass are included and the full hydrodynamic equation for pions is given. The in-medium dispersion relation of pions in the neutron rich background state and the possibility of the phase transition to pion condensation are also discussed.

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47

Chen, Xiao Ying, Dai Hai Liu e Jing Lu. "The Sedimentary Environment of Current Estuary and Abandoned Estuary at the Modern Yellow River Delta". Advanced Materials Research 356-360 (ottobre 2011): 914–19. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.914.

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Abstract (sommario):

Based upon statistics of sediment parameters and sediment moving modes from probability cumulative distribution curves, and combined with topography and hydrodynamics, the sedimentary environment at the intertidal flats of Qing 8 estuary (1996-now) and Diaokou estuary (1964-1976) at the Yellow River Delta was discussed in depth in present study. The results demonstrated that sediment grain size parameters can clearly reveal hydrodynamic condition of the sedimentary environment. Core C1 at current estuary was divided into four layers. The corresponding hydrodynamic conditions from top to bottom varied from strong to fluctuating between strong and weak, and finally to weak. Meanwhile, Core A1 at abandoned estuary can be divided into three layers and corresponding hydrodynamics from top to bottom changed from fairly strong to rather strong. Furthermore, the sedimentary facies of two cores were identified and they depended on water and sediment discharge from the Yellow River.

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48

Zhong, Fusheng, e Anlin Wang. "Rule Optimization of Self-organization Control of Traffic Signals in Urban Net Based on Hydrodynamic". MATEC Web of Conferences 237 (2018): 03004. http://dx.doi.org/10.1051/matecconf/201823703004.

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Abstract (sommario):

Prior researchers indicate that hydrodynamics models of traffic-flow is lack of description of changing mechanism under urban traffic, and self-organization control system can not explain the dynamic characteristics of urban traffic flow clearly. The aim of the paper is to puts forward an optimized method on control rules that make the united application of hydrodynamics and self-organization system in signal control. The parameter sets of control rules are built from parameter sets of road network which are evolution under hydrodynamic equations such as the length of each lane, phase, queue length and so on .With the aim of the maximum traffic volume at each intersection in the road network, the control rules optimize its parameter sets to adapt to the dynamic change. By means of the computer simulation, the application of signal self-organizing control under hydrodynamic is proved effective in urban traffic.a

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49

Malang, Jameson, Perumal Kumar e Agus Saptoro. "Computational Fluid Dynamics-Based Hydrodynamics Studies in Packed Bed Columns: Current Status and Future Directions". International Journal of Chemical Reactor Engineering 13, n. 3 (1 settembre 2015): 289–303. http://dx.doi.org/10.1515/ijcre-2014-0121.

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Abstract (sommario):

Abstract A careful review of the literature reveals that extensive research has been done on the hydrodynamics in packed bed columns using turbulence models. It can be noted that the choice of turbulence model is influenced by the number of phases, type of fluid, Reynolds number range and the type of packing. Thus, comparison of turbulence models for the selection of a suitable model assumes great importance for the better prediction of flow pattern. This is due to the fact that poor prediction of the flow pattern can lead to a limited heat and mass transfer model as the rate of transfer processes in packed bed is governed by the hydrodynamics of the packed bed. The aim of this paper is to give a review of the computational fluid dynamics (CFD)-based hydrodynamics studies of packed bed columns with the primary interest of studying pressure drop and drag coefficient in packed beds. From the literature survey in Science Direct database, more than 48,000 papers related to packed bed columns have been published with more than 3,000 papers focused on the hydrodynamic studies of the bed to date. Unfortunately, there are only a few studies reported on the hydrodynamics of packed columns under supercritical fluid condition. Therefore, it is imperative that the future work has to focus on the hydrodynamics of supercritical packed column and particularly on the selection of suitable turbulence model.

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50

KODAMA, T., T. KOIDE, G. S. DENICOL e P. MOTA. "OPEN PROBLEMS IN THE HYDRODYNAMICAL APPROACH TO RELATIVISTIC HEAVY ION COLLISIONS". International Journal of Modern Physics E 16, n. 03 (aprile 2007): 763–75. http://dx.doi.org/10.1142/s0218301307006265.

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Abstract (sommario):

We discuss some open problems in hydrodynamical approach to the relativistic heavy ion collisions. In particular, we propose a new, very simple alternative approach to the relativistic dissipative hydrodynamics of Israel and Stewart.

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