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Littérature scientifique sur le sujet « Stationary micropolar fluids equations »

Auteur : Grafiati

Publié le 21 décembre 2024

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Articles de revues sur le sujet "Stationary micropolar fluids equations"

Duarte-Leiva, Cristian, Sebastián Lorca et Exequiel Mallea-Zepeda. « A 3D Non-Stationary Micropolar Fluids Equations with Navier Slip Boundary Conditions ». Symmetry 13, n^o 8 (26 juillet 2021) : 1348. http://dx.doi.org/10.3390/sym13081348.

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Micropolar fluids are fluids with microstructure and belong to a class of fluids with asymmetric stress tensor that called Polar fluids, and include, as a special case, the well-established Navier–Stokes model. In this work we study a 3D micropolar fluids model with Navier boundary conditions without friction for the velocity field and homogeneous Dirichlet boundary conditions for the angular velocity. Using the Galerkin method, we prove the existence of weak solutions and establish a Prodi–Serrin regularity type result which allow us to obtain global-in-time strong solutions at finite time.

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Kocić, Miloš, Živojin Stamenković, Jelena Petrović et Jasmina Bogdanović-Jovanović. « MHD micropolar fluid flow in porous media ». Advances in Mechanical Engineering 15, n^o 6 (juin 2023) : 168781322311784. http://dx.doi.org/10.1177/16878132231178436.

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The analysis of mass and heat transfer in magnetohydrodynamic (MHD) flows has significant applications in heat exchangers, cooling nuclear reactors, designing energy systems and casting and injection processes of different types of fluids. On the other hand, extraction of crude oil, the flow of human or animal blood, as well as other polymer fluids or liquid crystals are just some examples of micropolar fluid flows. Due to the broad application spectrum of the theory of micropolar fluid flows, and the significance the impact the external magnetic field has on the flow of these fluids, this paper considers the stationary flow of a micropolar fluid between two plates under the influence of an external magnetic field which is perpendicular to the direction of the flow. Stationary plates are maintained at constant and different temperatures, while the whole problem is considered in the non-inductive approximation. The equation system used to define the physical problem under consideration is reduced to the system of differential equations that have been solved analytically and the solutions of which are of general nature. In addition to the solutions for velocity, microrotation and temperature, the paper gives solutions for shear stress at plates, the Nusselt number and flow rate. The provided solutions have been applied in order to reach some general conclusions about the influence of the magnetic field and physical characteristics of a micropolar fluid and the characteristics of porous media on the nature of micropolar fluid flows in porous media by means of chart analysis. General conclusions, obtained in the result analysis in this paper, give us the opportunity to understand the flows of micropolar fluids and highlight their significance.

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Eldabe, N. T., et M. Y. Abou-Zeid. « The Wall Properties Effect on Peristaltic Transport of Micropolar Non-Newtonian Fluid with Heat and Mass Transfer ». Mathematical Problems in Engineering 2010 (2010) : 1–40. http://dx.doi.org/10.1155/2010/898062.

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The problem of the unsteady peristaltic mechanism with heat and mass transfer of an incompressible micropolar non-Newtonian fluid in a two-dimensional channel. The flow includes the viscoelastic wall properties and micropolar fluid parameters using the equations of the fluid as well as of the deformable boundaries. A perturbation solution is obtained, which satisfies the momentum, angular momentum, energy, and concentration equations for case of free pumping (original stationary fluid). Numerical results for the stream function, temperature, and concentration distributions are obtained. Several graphs of physical interest are displayed and discussed.

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WENG, HUEI CHU, CHA'O-KUANG CHEN et MIN-HSING CHANG. « Stability of micropolar fluid flow between concentric rotating cylinders ». Journal of Fluid Mechanics 631 (17 juillet 2009) : 343–62. http://dx.doi.org/10.1017/s0022112009007150.

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In this study, the theory of micropolar fluids is employed to study the stability problem of flow between two concentric rotating cylinders. The field equations subject to no-slip conditions (non-zero velocity and microrotation velocity components) at the wall surfaces are solved. The analytical solutions of the velocity and microrotation velocity fields as well as the shear stress difference, couple stress and strain rate for basic flow are obtained. The equations with respect to non-axisymmetric disturbances are derived and solved by a direct numerical procedure. It is found that non-zero wall-surface microrotation velocity makes the flow faster and more unstable. Moreover, it tends to reduce the limits of critical non-axisymmetric disturbances. The effect on the stability characteristics can be magnified by increasing the microstructure or couple-stress parameter or the microinertia parameter for the cases of corotating cylinders and a stationary outer cylinder or by decreasing the radius ratio or the microinertia parameter for the case of counterrotating cylinders.

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Xing, Xin, et Demin Liu. « Numerical Analysis and Comparison of Three Iterative Methods Based on Finite Element for the 2D/3D Stationary Micropolar Fluid Equations ». Entropy 24, n^o 5 (29 avril 2022) : 628. http://dx.doi.org/10.3390/e24050628.

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In this paper, three iterative methods (Stokes, Newton and Oseen iterative methods) based on finite element discretization for the stationary micropolar fluid equations are proposed, analyzed and compared. The stability and error estimation for the Stokes and Newton iterative methods are obtained under the strong uniqueness conditions. In addition, the stability and error estimation for the Oseen iterative method are derived under the uniqueness condition of the weak solution. Finally, numerical examples test the applicability and the effectiveness of the three iterative methods.

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Salemovic, Dusko, Aleksandar Dedic et Bosko Jovanovic. « Micropolar fluid between two coaxial cylinders (numerical approach) ». Theoretical and Applied Mechanics 48, n^o 2 (2021) : 159–69. http://dx.doi.org/10.2298/tam210823012s.

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The paper describes the flow of a suspension which is a mixture of two phases: liquid and solid granules. The continuum model with microstructure is introduced, which involves two independent kinematic quantities: the velocity vector and the micro-rotation vector. The physical analogy is based on the movement of the suspension between two coaxial cylinders. The inner cylinder is stationary and the outer one rotates with constant angular velocity. This physical analogy enabled a mathematical model in a form of two coupled differential equations with variable coefficients. The aim of the paper is to present the numerical aspect of the solution for this complex mathematical model. It is assumed that the solid granules are identically oriented and that under the influence of the fluid they move translationally or rotate around the symmetry axis but the direction of their symmetry axes does not change. The solution was obtained by the ordinary finite difference method, and then the corresponding sets of points (nodes) were routed by interpolation graphics.

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Burmasheva, N. V., et E. Yu Prosviryakov. « Exact solutions to the NAVIER–STOKES equations for unidirectional flows of micropolar fluids in a mass force field ». Diagnostics, Resource and Mechanics of materials and structures, n^o 3 (juin 2024) : 41–63. http://dx.doi.org/10.17804/2410-9908.2024.3.041-063.

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The paper presents a family of exact solutions to the Navier-Stokes equation system used to describe inhomogeneous unidirectional flows of a viscous fluid taking into account couple stresses. Despite the presence of only one non-zero component of the velocity vector, this component depends on time and two spatial coordinates. In view of the incompressibility equation, which is a special case of the mass conservation law, there is no dependence on the third spatial coordinate. The resulting redefined system of equations is considered in a non-stationary formulation. The construction of a family of exact solutions for the resulting redefined equation system begins with the analysis of the homogeneous Couette-type solution as the simplest in this class. Further, the structure of the solution gradually becomes more complicated, i.e. the profile of the only non-zero component of the velocity vector is represented as a polynomial depending on one variable (horizontal coordinate). The polynomial coefficients functionally depend on the second (vertical) coordinate and time. It is shown that, due to the strong nonlinearity and heterogeneity of the equation under study, the sum of its individual solutions is not a solution. It is also shown that, in the linearly independent basis of the power functions of the horizontal coordinate, which determine the above-mentioned polynomial, the equation in question decomposes into a chain of the simplest homogeneous and inhomogeneous parabolic partial differential equations. These equations are integrated sequentially, the order of integration being described separately. The results reported in this study extend the family of previously presented exact solutions to describing unidirectional unsteady flows.

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Arnaud, M. M., G. M. de Araùjo, M. M. Freitas et E. F. L. Lucena. « ON A SYSTEM OF EQUATIONS OF A NON-NEWTONIAN MICROPOLAR FLUID IN THE STATIONARY FORM ». Far East Journal of Applied Mathematics 97, n^o 4 (2 décembre 2017) : 125–42. http://dx.doi.org/10.17654/am097040125.

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Chen, James, James D. Lee et Chunlei Liang. « Constitutive equations of Micropolar electromagnetic fluids ». Journal of Non-Newtonian Fluid Mechanics 166, n^o 14-15 (août 2011) : 867–74. http://dx.doi.org/10.1016/j.jnnfm.2011.05.004.

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IDO, Yasushi. « Basic Equations of Micropolar Magnetic Fluids ». Transactions of the Japan Society of Mechanical Engineers Series B 70, n^o 696 (2004) : 2065–70. http://dx.doi.org/10.1299/kikaib.70.2065.

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Thèses sur le sujet "Stationary micropolar fluids equations"

Llerena, Montenegro Henry David. « Sur l'interdépendance des variables dans l'étude de quelques équations de la mécanique des fluides ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASM048.

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Cette thèse est consacrée à l'étude de la relation entre les variables dans les équations des fluides micro-polaires. Ce système, basé sur les équations de Navier-Stokes, consiste en un couplage de deux variables: le champ de vitesse vec{u} et le champ de micro-rotation vec{w}. Notre objectif est de mieux comprendre comment l'information concernant une variable influence le comportement de l'autre. À cette fin, nous avons divisé cette thèse en quatre chapitres, où nous étudierons les propriétés de régularité locale des solutions faibles de type Leray, puis nous nous concentrerons sur la régularité et l'unicité des solutions faibles dans le cas stationnaire. Le premier chapitre présente une rapide déduction physique des équations micro-polaires, suivie de la construction des solutions faibles de type Leray. Dans le chapitre 2, nous commençons par prouver un gain d'intégrabilité pour les deux variables vec{u} et vec{w} lorsque la vitesse appartient à certains espaces de Morrey. Ce résultat souligne un effet de domination de la vitesse. Nous montrons ensuite que cet effet peut également être observé dans le cadre de la théorie de Caffarelli-Kohn-Nirenberg, i.e., sous une hypothèse de petitesse supplémentaire uniquement sur le gradient de la vitesse, nous pouvons démontrer que la solution devient Hölder continue. Pour cela, nous introduisons la notion de solution partiellement adaptée, qui est fondamentale dans ce travail et représente l'une des principales nouveautés. Dans la dernière section de ce chapitre, nous obtenons des résultats similaires dans le contexte du critère de Serrin. Dans le chapitre 3, nous nous concentrons sur le comportement de la norme L^3 de la vitesse vec{u} autour des possibles points où la régularité peut être perdue. Plus précisément, nous établissons un critère d'explosion pour la norme L^3 de la vitesse et améliorons ce résultat en présentant un phénomène de concentration. Nous vérifions également que le cas limite L^infty_t L^3_x du critère de Serrin reste valable pour les équations des fluides micro-polaires. Enfin, le problème de l'existence et de l'unicité des équations stationnaires des fluides micro-polaires est abordé dans le chapitre 4. En effet, nous prouvons l'existence de solutions faibles (vec{u}, vec{w}) dans l'espace d'énergie naturel dot{H}^1(mathbb{R}^3) imes H^1(mathbb{R}^3). De plus, en utilisant la relation entre les variables, nous déduisons que ces solutions sont régulières. Il convient de noter que la solution triviale peut ne pas être unique, et pour surmonter cette difficulté, nous développons un théorème de type Liouville. Ainsi, nous démontrons qu'en imposant une décroissance plus forte à l'infini uniquement sur vec{u}, nous pouvons en déduire l'unicité de la solution triviale (vec{u},vec{w})=(0,0)
This thesis is devoted to the study of the relationship between the variables in the micropolar fluids equations. This system, which is based on the Navier-Stokes equations, consists in a coupling of two variables: the velocity field vec{u} and the microrotation field vec{w}. Our aim is to provide a better understanding of how information about one variable influences the behavior of the other. To this end, we have divided this thesis into four chapters, where we will study the local regularity properties of Leray-type weak solutions, and later we will focus on the regularity and uniqueness of weak solutions for the stationary case. The first chapter presents a brief physical derivation of the micropolar equations followed by the construction of the Leray-type weak solutions. In Chapter 2, we begin by proving a gain of integrability for both variables vec{u} and vec{w} whenever the velocity belongs to certain Morrey spaces. This result highlights an effect of domination by the velocity. We then show that this effect can also be observed within the framework of the Caffarelli-Kohn-Nirenberg theory, i.e., under an additional smallness hypothesis only on the gradient of the velocity, we can demonstrate that the solution becomes Hölder continuous. For this, we introduce the notion of a partial suitable solution, which is fundamental in this work and represents one of the main novelties. In the last section of this chapter, we derive similar results in the context of the Serrin criterion. In Chapter 3, we focus on the behavior of the L^3-norm of the velocity vec{u} near possible points where regularity may get lost. More precisely, we establish a blow-up criterion for the L^3 norm of the velocity and we improve this result by presenting a concentration phenomenon. We also verify that the limit point L^infty_t L^3_x of the Serrin criterion remains valid for the micropolar fluids equations. Finally, the problem of existence and uniqueness for the stationary micropolar fluids equations is addressed in Chapter 4. Indeed, we prove the existence of weak solutions (vec{u}, vec{w}) in the natural energy space dot{H}^1(mathbb{R}^3) imes H^1(mathbb{R}^3). Moreover, by using the relationship between the variables, we deduce that these solutions are regular. It is worth noting that the trivial solution may not be unique, and to overcome this difficulty, we develop a Liouville-type theorem. Hence, we demonstrate that by imposing stronger decay at infinity only on vec{u}, we can infer the uniqueness of the trivial solution (vec{u},vec{w})=(0,0)

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Gumgum, Sevin. « The Dual Reciprocity Boundary Element Method Solution Of Fluid Flow Problems ». Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611605/index.pdf.

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In this thesis, the two-dimensional, transient, laminar flow of viscous and incompressible fluids is solved by using the dual reciprocity boundary element method (DRBEM). Natural convection and mixed convection flows are also solved with the addition of energy equation. Solutions of natural convection flow of nanofluids and micropolar fluids in enclosures are obtained for highly large values of Rayleigh number. The fundamental solution of Laplace equation is used for obtaining boundary element method (BEM) matrices whereas all the other terms in the differential equations governing the flows are considered as nonhomogeneity. This is the main advantage of DRBEM to tackle the nonlinearities in the equations with considerably small computational cost. All the convective terms are evaluated by using the DRBEM coordinate matrix which is already computed in the formulation of nonlinear terms. The resulting systems of initial value problems with respect to time are solved with forward and central differences using relaxation parameters, and the fourth-order Runge-Kutta method. The numerical stability analysis is developed for the flow problems considered with respect to the choice of the time step, relaxation parameters and problem constants. The stability analysis is made through an eigenvalue decomposition of the final coefficient matrix in the DRBEM discretized system. It is found that the implicit central difference time integration scheme with relaxation parameter value close to one, and quite large time steps gives numerically stable solutions for all flow problems solved in the thesis. One-and-two-sided lid-driven cavity flow, natural and mixed convection flows in cavities, natural convection flow of nanofluids and micropolar fluids in enclosures are solved with several geometric configurations. The solutions are visualized in terms of streamlines, vorticity, microrotation, pressure contours, isotherms and flow vectors to simulate the flow behaviour.

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Chapitres de livres sur le sujet "Stationary micropolar fluids equations"

Łukaszewicz, Grzegorz. « Stationary Problems ». Dans Micropolar Fluids, 59–110. Boston, MA : Birkhäuser Boston, 1999. http://dx.doi.org/10.1007/978-1-4612-0641-5_3.

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Shklyaev, Sergey, et Alexander Nepomnyashchy. « Convection in Binary Liquids : Amplitude Equations for Stationary and Oscillatory Patterns ». Dans Longwave Instabilities and Patterns in Fluids, 125–208. New York, NY : Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-7590-7_4.

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Khapalov, Alexander. « Local Controllability of 2D and 3D Swimmers : The Case of Non-stationary Stokes Equations ». Dans Bio-Mimetic Swimmers in Incompressible Fluids, 71–89. Cham : Springer International Publishing, 2012. http://dx.doi.org/10.1007/978-3-030-85285-6_7.

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Merkin, John H., Ioan Pop, Yian Yian Lok et Teodor Grosan. « Basic equations and mathematical methods ». Dans Similarity Solutions for the Boundary Layer Flow and Heat Transfer of Viscous Fluids, Nanofluids, Porous Media, and Micropolar Fluids, 1–21. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-821188-5.00002-3.

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Conca, C., R. Gormaz, E. Ortega et M. Rojas. « Existence and uniqueness of a strong solution for nonhomogeneous micropolar fluids ». Dans Nonlinear Partial Differential Equations and their Applications - Collège de France Seminar Volume XIV, 213–41. Elsevier, 2002. http://dx.doi.org/10.1016/s0168-2024(02)80012-1.

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« ON THE EXISTENCE OF SOLUTIONS FOR NON-STATIONARY SECOND-GRADE FLUIDS ». Dans Navier-Stokes Equations and Related Nonlinear Problems, 15–30. De Gruyter, 1998. http://dx.doi.org/10.1515/9783112319291-003.

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Chimowitz, Eldred H. « Supercritical Adsorption ». Dans Introduction to Critical Phenomena in Fluids. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195119305.003.0008.

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In this chapter, we discuss adsorption phenomena in supercritical systems, a situation that occurs in many application areas in chemical-process and materials engineering. An example of a commercial application in this area, which has achieved wide acceptance as a tool in analytical chemistry, is supercritical fluid chromatography (SFC). Not only is SFC a powerful technique for chemical analysis, but it also is a useful method for measuring transportive and thermodynamic properties in the near-critical systems. In the next section, we analyze adsorption-column dynamics using simple dynamic models, and describe how data from a chromatographic column can be used to estimate various thermodynamic and transport properties.We then proceed to discuss the effects of proximity to the critical point on adsorption behavior in these systems. The closer the system is to its critical point, the more interesting is its behavior. For very dilute solute systems, like those considered here, the energy balance is often ignored to a first approximation; this leads to a simple set of mass-balance equations defining transport for each species. These equations can be developed to various levels of complexity, depending upon the treatment of the adsorbent (stationary phase). The conceptual view of these phases can span a wide range of possibilities ranging from completely nonporous solids (fused structures) to porous materials with complicated ill-defined pore structures. Given these considerations, it is customary to make the following assumptions in the development of a simple model of adsorber-bed dynamics: . . .1. The stationary and mobile phases are continuous in the direction of the flow, with the fluid phase possessing a flat velocity profile (“plug” flow).. . . . . . 2. The porosity of the stationary phase is considered constant irrespective of pressure and temperature conditions (i.e., it is incompressible). . . . . . .3. The column is considered to be radially homogeneous, leading to a set of equations with one spatially independent variable, representing distance along the column axis. . . . . . . 4. The dispersion term in the model equation represents the combined effects of molecular diffusion and dispersion due to convective stirring in the bed. These effects are combined into an effective phenomenological dispersion coefficient, considered to be constant throughout the column. . . .

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Ghergu, Marius, et Vicenţiu D. Rădulescu. « Sublinear Perturbations of Singular Elliptic Problems ». Dans Singular Elliptic Problems : Bifurcation and Asymptotic Analysis, 93–124. Oxford University PressNew York, NY, 2008. http://dx.doi.org/10.1093/oso/9780195334722.003.0004.

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Abstract Singular problems arise in the study of non-Newtonian fluids, boundary layer phenomena for viscous fluids, chemical heterogeneous catalysts, as well as in the theory of heat conduction in electrically conducting materials. The associated singular stationary or evolution equations describe various physical phenomena. For instance, superdiffusivity equations of this type have been proposed by de Gennes [60] as a model for long-range Van der Waals interactions in thin films spreading on solid surfaces. Singular equations also appear in the study of cellular automata and interacting particle systems with self-organized criticality (see [39]), as well as to describe the flow over an impermeable plate (see [38]).

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« Chapter 2 Correctness “IN THE WHOLE” of the Boundary Problems for Equations of One-Dimensional Non-Stationary Motion of a Viscous Gas ». Dans Boundary Value Problems in Mechanics of Nonhomogeneous Fluids, 39–100. Elsevier, 1990. http://dx.doi.org/10.1016/s0168-2024(08)70071-7.

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Actes de conférences sur le sujet "Stationary micropolar fluids equations"

Lasinger, Katrin, Christoph Vogel et Konrad Schindler. « Volumetric Flow Estimation for Incompressible Fluids Using the Stationary Stokes Equations ». Dans 2017 IEEE International Conference on Computer Vision (ICCV). IEEE, 2017. http://dx.doi.org/10.1109/iccv.2017.280.

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Najafi, A., F. Daneshmand et S. R. Mohebpour. « Analysis of Vibrating Micropolar Plate in Contact With a Fluid ». Dans ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-31036.

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Micropolar theory constitutes extension of the classical field theories. It is based on the idea that every particles of the material can make both micro rotation and volumetric micro elongation in addition to the bulk deformation. Since this theory includes the effects of micro structure which could affect the overall behaviour of the medium, it reflects the physical realities much better than the classical theory for the engineering materials. In the micropolar theory, the material points are considered to possess orientations. A material point carrying three rigid directors introduces one extra degree of freedom over the classical theory. This is because in micropolar continuum, a point is endowed with three rigid directors only. A material point is then equipped with the degrees of freedom for rigid rotations, in addition to the classical translational degrees of freedom. In fact, the micropolar covers the results of the classical continuum mechanics. The micropolar theory recently takes attentions in fluid mechanics and mathematicians and engineers are implementing this theory in various theoretical and practical applications. In this paper the fluid-structure analysis of a vibrating micropolar plate in contact with a fluid is considered. The fluid is contained in a cube which all faces except for one of the lateral faces are rigid. The only non-rigid lateral face is made of a flexible micropolar plate and therefore, interacts with the fluid. An analytical approach is utilized to investigate the vibration characteristics of the aforementioned fluid-structure problem. The fluid is non-viscous and incompressible. Duplicate Chebyshev series, multiplied by boundary functions are used as admissible functions and the frequency equations of the micropolar plate are obtained by the use of Chebyshev-Ritz method. Also the vibration analysis of the plates modeled by micropolar theory has been done. This analysis shows that some additional frequencies due to the micropolarity of the plate appears among the values of the frequencies obtained in the classical theory of elasticity, as expected. These new frequencies are called micro-rotational waves. We also observed that when the micropolar material constants vanish, these additional frequencies disappear and only the classical frequencies remain. Specially, we observed that these additional frequencies are more sensitive to the change of the micro elastic constants than the classical frequencies. The frequencies and mode shapes of the coupled fluid structure interaction problem are obtained in the present study based on the micropolar and classical modeling. The numerical results for the problem are compared with those obtained by the analytical method for their differences and to confirm the proposed method. The microrotatinal wave frequencies and mode shapes are also developed. The results show that the natural frequencies and mode shapes for the transverse vibrations of the problem are in good agreement with the classical one and our knowledge from the physical nature of the problem.

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Naumann, Joachim. « On weak solutions to the equations of non-stationary motion of heat-conducting incompressible viscous fluids : defect measure and energy equality ». Dans Parabolic and Navier–Stokes equations. Warsaw : Institute of Mathematics Polish Academy of Sciences, 2008. http://dx.doi.org/10.4064/bc81-0-19.

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Matousˇek, Va´clav. « Pressure Drop in Slurry Pipe With Stationary Deposit ». Dans ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37322.

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Majority of slurry pipelines operates at flow velocities high enough to maintain all transported solid particles in motion. Nevertheless, it happens sometimes that pipeline operations with stationary deposits of solids at the bottom of a pipe are found in practice (e.g. sand transportation through long pipelines connected with a dredge). Many different models are available for a prediction of the pressure drop in a slurry pipe without a deposit. Very little is known about flows with stationary deposits. The paper discusses pipe flows of sand-water slurries at velocities lower than the deposition-limit velocity. Results of laboratory tests of slurry flows with granular beds at the bottom of a slurry pipe are analyzed with an aim to establish a predictive model for the frictional pressure drop associated with this type of slurry flow. The pressure-drop model is based on a description of prevailing mechanisms that are identified to govern solids dispersion and solids friction in slurry flows at different conditions (e.g. different average concentrations of solids above the stationary bed, different dimensions of the discharge area above the bed etc.). The proposed model is composed of continuity, momentum, boundary-friction and particle-dispersion equations. The empirical stratification-ratio equation relates the effect of particle dispersion within the slurry flow with the flow friction at the top of the stationary deposit. This friction is recognized as a major contributor to the total pressure drop in the slurry flow through a pipe with a stationary deposit.

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Shan, Hua, Sung-Eun Kim et Bong Rhee. « A Fully Coupled Flow and 6-DOF Motion Solver in Multiple Reference Frames ». Dans ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-3210.

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In many computational fluid dynamics (CFD) applications involving a single rotating part, such as the flow through an open water propeller rotating at a constant rpm, it is convenient to formulate the governing equations in a non-inertial rotating frame. For flow problems consisting of both stationary and rotating parts, e.g. the stator and the rotor of a turbine, or the hull and propeller of a ship, the multiple reference frames (MRF) approach has been widely used. In most existing MRF models, the computation domain is divided into stationary and rotating zones. In the stationary zone, the flow equations are formulated in the inertial frame, while in the rotating zone, the equations are solved in the non-inertial rotating frame. Also, the flow is assumed to be steady in both zones and the flow solution in the rotating zone can be interpreted as the phase-locked time average result. Compared with other approaches, such as the actuator disk (body-force) model, the MRF approach is superior because it accounts for the actual geometry of the rotating part, e.g. propeller blades. A more complicated situation occurs when the flow solver is coupled to the six degrees of freedom (6-DOF) equations of rigid-body motion in predicting the maneuver of a self-propelled surface or underwater vehicle. In many applications, the propeller is replaced by the actuator disk model. The current work attempts to extend the MRF approach to the 6-DOF maneuvering problems. The governing equations for unsteady incompressible flow in a non-inertial frame have been extended to the flow equations in multiple reference frames: a hull-fixed frame that undergoes translation and rotation predicted by the 6-DOF equations of motion and a propeller-fixed frame in relative rotation with respect to the hull. Because of the large disparity between time scales in the 6-DOF rigid body motion of the hull and the relative rotational motion of the propeller, the phase-locked solution in the propeller MRF zone is considered a reasonable approximation for the actual flow around the propeller. The flow equations are coupled to the 6-DOF equations of motion using an iterative coupling algorithm. The coupled solver has been developed as part of NavyFOAM. The theoretical framework and the numerical implementation of the coupled solver are outlined in this paper. Some numerical test results are also presented.

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Matousˇek, Va´clav, et Jan Krupicˇka. « Liquid-Solid Flows Above Deposit in Pipe : Prediction of Hydraulic Gradient and Deposit Thickness ». Dans ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78125.

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A predictive model for the pressure drop in a slurry flow above a stationary bed was presented at the last Liquid-Solid Flow Symposium in 2007. Since then the model has been further refined and validated using experimental data from the tests performed at the Institute of Hydrodynamics ASCR and from the literature. The new version of the model enables to choose a set of appropriate equations in order to predict the hydraulic gradient (the frictional pressure drop) and the thickness of the stationary bed for pipe flows of various average velocities of slurry and delivered concentrations of solids. The paper describes the structure and components of the model and discusses model predictive abilities by comparing model predictions with the new experimental data gained for slurries of two different fractions of sand (respectively fine to medium and medium sands) at various velocities and solids concentrations in a 100-mm pipe.

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Fleig, Oliver, et Chuichi Arakawa. « Aeroacoustics Simulation Around a Wind Turbine Blade Using Compressible LES and Linearized Euler Equations ». Dans ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45368.

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There is a strong need to investigate aerodynamic noise caused by large and fast rotating wind turbines, especially trailing edge and tip noise. This work constitutes the first part of a project which aims to simulate the broadband tip noise emitted when the wind turbine is in operation. Several aeroacoustics methods are analyzed and their suitability for a typical wind turbine blade is assessed. A stationary wind turbine blade in an incident flow with a large region of separated flow is studied. The surface pressure fluctuations are calculated using compressible Large-Eddy simulation (LES). The aerodynamic noise perceived in the far-field is predicted by simulating the propagation of the pressure perturbations using LES and Linearized Euler equations (LEE) in the near field and Kirchhoff’s integral method in the far-field. It was found that for the present wind turbine blade with a large region of separated flow and thus relatively large fluctuations, LES with a fine enough mesh and a third-order upwind scheme is able to compute the propagation of acoustic waves as accurately as LEE with higher order schemes and separate treatment of acoustic perturbations. The method described in this paper will be used in the future to analyze a full wind turbine blade with the aim of optimizing the tip shape for reduced noise emission.

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Pérez, José, Rafael Baez, Jose Terrazas, Arturo Rodríguez, Daniel Villanueva, Olac Fuentes, Vinod Kumar, Brandon Paez et Abdiel Cruz. « Physics-Informed Long-Short Term Memory Neural Network Performance on Holloman High-Speed Test Track Sled Study ». Dans ASME 2022 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/fedsm2022-86953.

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Abstract Physics Informed Neural Networks (PINNs) incorporate known physics equations into a network to reduce training time and increase accuracy. Traditional PINNs approaches are based on dense networks that do not consider the fact that simulations are a type of sequential data. Long-Short Term Memory (LSTM) networks are a modified version of Recurrent Neural Networks (RNNs) which are used to analyze sequential datasets. We propose a Physics Informed LSTM network that leverages the power of LSTMs for sequential datasets that also incorporates the governing physics equations of 2D incompressible Navier-Stokes fluid to analyze fluid flow around a stationary geometry resembling the water braking mechanism at the Holloman High-Speed Test Track. Currently, simulation data to analyze the fluid flow of the braking mechanism is generated through ANSYS and is costly, taking several days to generate a single simulation. By incorporating physics equations, our proposed Physics-Informed LSTM network was able to predict the last 20% of a simulation given the first 80% within a small margin of error in a shorter amount of time than a non-informed LSTM. This demonstrates the potential that physics-informed networks that leverage sequential information may have at speeding up computational fluid dynamics simulations and serves as a first step towards adapting PINNs for more advanced network architectures.

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Mukherjee, Abhijit, et Satish G. Kandlikar. « Numerical Study of an Evaporating Meniscus on a Moving Heated Surface ». Dans ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56678.

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The present study is performed to numerically analyze an evaporating meniscus on a moving heated surface. This phenomenon is similar to the one observed at the base of a vapor bubble during nucleate boiling. The complete Navier-Stokes equations along with continuity and energy equations are solved. The liquid vapor interface is captured using the level set technique. A column of liquid is placed between two parallel plates with an inlet for water at the top to feed the meniscus. The location of water inlet at the top is kept fixed and the bottom wall is imparted with a velocity. Calculations are done in two-dimensions with a fixed distance between the plates. The main objective is to study the velocity and temperature fields inside the meniscus and calculate the wall heat transfer. The results show that the wall velocity creates a circulation near the meniscus base causing increased wall heat transfer as compared to a stationary meniscus. The local wall heat transfer is found to vary significantly along the meniscus base, the highest being near the advancing contact line.

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Mishra, Srishti, Mukul Tomar, Adeel Ahmad, Satvik Jain et Naveen Kumar. « Numerical Study of Forced Convection in Different Fluids From Stationary Heated Cylinders in a Square Enclosure ». Dans ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87032.

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This paper performs a numerical study of forced convection heat transfer in a square enclosure with four identical stationary cylinders with single inlet and outlet ports. The ratio of the diameter of the cylinder to the length of the enclosure is kept constant at 0.1 with a fixed spacing between the cylinders. The enclosure walls are adiabatic while the cylinders are maintained at a constant temperature. The governing equations are solved for laminar, steady state and incompressible flow for different fluids namely air, water, and ethylene glycol. The study aims to determine the effect of varying Reynolds number (5 ≤ Re ≤ 100) and fluid properties (0.7 ≤ Pr < 200) on heat transfer rate and flow characteristics. The results of the study are presented in terms of streamlines, isotherm contours, and surface-averaged Nusselt numbers. The 2-D modeling and simulation have been conducted using ANSYS 16.0.

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