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International Conference on Computational Heat and Mass Transfer-2015

作者： Nagarajan, Nithyadevi Periyasamy, Umadevi Bharathiar Univ Dept Math Coimbatore 641046 Tamil Nadu India

Steady laminar natural convection around a heat conducting and generating solid body inside a two-dimensional tilted square enclosure with different thermal boundaries are investigated numerically. The mathematical model is governed by the coupled equation of mass, momentum and energy. These equations are solved using simple algorithm by means of the finite-volume method together with under-relaxation technique. Effect of angle of inclination of enclosure, aspect ratio of solid-enclosure, temperature difference ratio of solid-fluid and the thermal conductivity ratio of solid-fluid are analyzed. The fluid circulation and the corresponding heat transport inside the enclosure are represented in terms of streamlines and isotherms respectively. (C) 2015 The Authors. Published by Elsevier Ltd.

关键词： Natural convection Thermal conductivity ratio simple algorithm Finite volume method

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Natural Convection in a Tilted Square Enclosure Having Heat Generating Solid Body and with Various Thermal Boundaries

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Procedia Engineering 2015年 127卷 1235-1242页

作者： Nithyadevi Nagarajan Umadevi Periyasamy Department of Mathematics Bharathiar University Coimbatore-641046 India

关键词： Natural convection Thermal conductivity ratio simple algorithm Finite volume method.

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Numerical simulation of the internal wave propagation in continuously densitystratified ocean

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Journal of Hydrodynamics 2014年第5期26卷 770-779页

作者：张洪生贾海青辜俊波李朋辉 College of Ocean Science and Engineering Shanghai Maritime University East China Electric Power Design Institute China Power Engineering Consulting Group

A numerical model is proposed to simulate the internal wave propagation in a continuously density-stratified ocean, and in the model, the momentum equations are derived from the Euler equations on the basis of the Boussinesq approximation. The governing equations, including the continuity equation and the momentum equations, are discretized with the finite volume method. The advection terms are treated with the total variation diminishing （TVD） scheme, and the simple algorithm is employed to solve the discretized governing equations. After the modeling test, the suitable TVD scheme is selected. The simple algorithm is modified to simplify the calculation process, and it is easily made to adapt to the TVD scheme. The Sommerfeld＇s radiation condition combined with a sponge layer is adopted at the outflow boundary. In the water flume with a constant water depth, the numerical results are compared to the analytical solutions with a good agreement. The numerical simulations are carried out for a wave flume with a submerged dike, and the model results are analyzed in detail. The results show that the present numerical model can effectively simulate the propagation of the internal wave.

关键词： internal wave continuously density-stratified fluid finite volume method simple algorithm numerical simulation

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Numerical algorithm for moving-boundary fluid dynamics problems and its testing

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COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2014年第10期54卷 1560-1570页

作者： Minakov, A. V. Siberian Fed Univ Krasnoyarsk 660041 Russia Russian Acad Sci Kutateladze Inst Thermal Phys Siberian Branch Novosibirsk 630090 Russia

A new Eulerian algorithm is proposed for computing incompressible flows with moving boundaries of arbitrary geometry. The algorithm can be regarded as an extension of Hirt's classical volume-of-fluid method. The results of its implementation and testing are presented. A comparison of the numerical results with experimental data and computations of other authors reveals good agreement.

关键词： moving boundary problems in fluid dynamics VOF method simple algorithm control volume method

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NUMERICAL MODELING FOR STEADY-STATE TWO PHASE FLOW IN GAS CONDENSATE PIPELINE 10

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10th International Pipeline Conference

作者： Wang, Zhi Gong, Jing Yin, Tienan China Univ Petr Natl Engn Lab Piping Safety 18 Fuxue Rd Beijing 102249 Peoples R China

ISBN: (纸本)9780791846131

Based on two-fluid approach, a numerical model coupled with phase behavior model and hydro-thermodynamic model, is presented for simulating steady-state two phase flow in gas condensate pipeline. In this model, two-fluid model is adopted for hydraulic computation and a simplified mixture energy equation is developed to couple hydraulic and thermodynamic calculation. simple algorithm is improved for application in one-dimensional steady-state simulation of two phase flow. Hydraulic and thermal is coupled as one-way coupling. The model was validated through comparison to field data from five operational gas-Condensate pipelines. It turns out that the numerical simulation in this paper has good stability and convergence and is capable of simulating the steady-state flow in gas-condensate pipelines.

关键词： two-fluid model gas-condensate pipeline steady-state simple algorithm

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A GENERALISED CONVERGENCE ACCELERATED PRESSURE-BASED SEGREGATED algorithm 11

A GENERALISED CONVERGENCE ACCELERATED PRESSURE-BASED SEGREGA...

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11th World Congress on Computational Mechanics (WCCM) / 5th European Conference on Computational Mechanics (ECCM) / 6th European Conference on Computational Fluid Dynamics (ECFD)

作者： Przulj, V. Ricardo UK Ltd Ricardo Software Shoreham By Sea BN43 5FG West Sussex England

ISBN: (纸本)9788494284472

This paper reports on the generalised pressure-based sequential algorithm applicable to polyhedral grids and incompressible/compressible flows. The algorithm is formulated in the context of a cell-centred finite-volume method. The central theme of the paper is the convergence acceleration of the algorithm. This is achieved by a straightforward treatment of cell neighbours velocity corrections as well as the pressure corrections due to grid non-orthogonality. These corrections appear in the pressure correction equation of the well-known simple method but they are commonly neglected. Here, and akin to the PISO method, the above corrections are treated explicitly by designing two or more correction steps. The full inclusion of the cell neighbour corrections requires an under-relaxation typically equal to the pressure under-relaxation. The algorithm is applied to a number of benchmark problems, covering laminar and turbulent as well as incompressible and compressible flows. The significantly improved convergence rate and satisfactory accuracy of the algorithm are demonstrated. An appreciable reduction of computing time is possible when using optimal under-relaxation factors and an optimal number of pressure corrections.

关键词： CFD Pressure-Based Method simple algorithm PISO Finite-Volume Co-located Unstructured Grid

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A new implicit fictitious domain method for the simulation of flow in complex geometries with heat transfer

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JOURNAL OF COMPUTATIONAL PHYSICS 2013年 237卷 21-45页

作者： Haeri, S. Shrimpton, J. S. Univ Southampton Sch Engn Sci Southampton SO17 1BJ Hants England

A numerical algorithm for the simulation of flow past immersed objects with heat transfer is proposed and validated which conforms with the ideas of the fictitious domain method. A momentum source term is added to account for the presence of the object and a heat source term is proposed to impose the Dirichlet boundary condition on the surface of the objects. The algorithm is an implicit fictitious domain based method where the entire fluid-immersed object domain assumed to be an incompressible fluid. The flow domain is constrained to be divergence free, whereas a rigidity constraint is imposed on the body domain. Heat transfer is similarly considered by assuming that the object domain is filled with a fluid with different thermal properties. The simple algorithm with a collocated grid arrangement is used for pressure-velocity coupling which is unconditionally stable. The algorithm is validated by considering stationary, forced motion and freely moving objects with both isothermal and freely variable temperature inside the object. Good agreement with previous numerical and experimental studies for all the test cases is observed. (c) 2012 Elsevier Inc. All rights reserved.

关键词： Fictitious domain Forced convection Free convection simple algorithm Collocated grid

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Numerical analysis of non-Newtonian blood flow and wall shear stress in realistic single, double and triple aorto-coronary bypasses

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013年第10期29卷 1057-1081页

作者： Vimmr, J. Jonasova, A. Bublik, O. Univ W Bohemia Fac Sci Appl NTIS European Ctr Excellence CZ-30614 Plzen Czech Republic

Considering the fact that hemodynamics plays an important role in the patency and overall performance of implanted bypass grafts, this work presents a numerical investigation of pulsatile non-Newtonian blood flow in three different patient-specific aorto-coronary bypasses. The three bypass models are distinguished from each other by the number of distal side-to-side and end-to-side anastomoses and denoted as single, double and triple bypasses. The mathematical model in the form of time-dependent nonlinear system of incompressible Navier-Stokes equations is coupled with the Carreau-Yasuda model describing the shear-thinning property of human blood and numerically solved using the principle of the simple algorithm and cell-centred finite volume method formulated for hybrid unstructured tetrahedral grids. The numerical results computed for non-Newtonian and Newtonian blood flow in the three aorto-coronary bypasses are compared and analysed with emphasis placed on the distribution of cycle-averaged wall shear stress and oscillatory shear index. As shown in this study, the non-Newtonian blood flow in all of the considered bypass models does not significantly differ from the Newtonian one. Our observations further suggest that, especially in the case of sequential grafts, the resulting flow field and shear stimulation are strongly influenced by the diameter of the vessels involved in the bypassing. Copyright (c) 2013 John Wiley & Sons, Ltd.

关键词： patient-specific aorto-coronary bypass pulsatile blood flow Carreau-Yasuda model finite volume method hybrid grid system simple algorithm

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Conjugate Heating Inside a Large Aspect Ratio Cavity with Finite Conductive Walls

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JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2013年第4期27卷 679-691页

作者： Pastrana, D. Cajas, J. C. Trevino, C. Univ Nacl Autonoma Mexico Fac Sci Mexico City 04510 DF Mexico Univ Nacl Autonoma Mexico Unidad Multidisciplinaria Docencia & Invest Fac Ciencias Sisal Yucatan Mexico

In this work, the transient two-dimensional conjugated (conduction-natural convection) heating of a fluid in a rectangular large aspect ratio cavity (height to length ratio = 12) is studied, with solid conductive walls of finite thickness. The equations of motion, written in nondimensional form, depending on five nondimensional parameters (the Rayleigh and Prandtl numbers, the ratio of the thermal conductivities and diffusivities of the fluid, the material of the cavity, and the nondimensional width of the walls), are solved numerically by the use of the simple algorithm. Three different heat transfer regimes were detected. The first one is the diffusive and quasi-diffusive, where heat is rapidly transferred along the cavity walls and then transmitted to the fluid from the internal boundary of the cavity, being almost independent on the Rayleigh number with a symmetrical response of the temperature and velocity fields. The second is diffusive-convective, where convection plays a more important role than in the previous case, symmetry is no longer preserved and different mechanisms of symmetry breakdown are present. The third one is the convective regime, where heat conduction along the walls is negligible and they can be assumed to be perfect insulators. Finally, it was found that the presence of conductive walls helps to stabilize and speed up the heating process, changing not only the magnitude of the heat flux to the system, but the physical response of the fluid inside the cavity.

关键词： High Aspect Ratio Natural Convection Thermal Diffusivity Convective Heat Transfer Heat Flux simple algorithm Thermal Conductivity Vortex Structure Entropy Generation Temperature Fields

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A simple based discontinuous Galerkin solver for steady incompressible flows

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JOURNAL OF COMPUTATIONAL PHYSICS 2013年 237卷 235-250页

作者： Klein, Benedikt Kummer, Florian Oberlack, Martin Tech Univ Darmstadt Dept Mech Engn Chair Fluid Dynam D-64287 Darmstadt Germany Tech Univ Darmstadt Ctr Smart Interfaces D-64287 Darmstadt Germany Tech Univ Darmstadt Grad Sch Computat Engn D-64293 Darmstadt Germany

In this paper we present how the well-known simple algorithm can be extended to solve the steady incompressible Navier-Stokes equations discretized by the discontinuous Galerkin method. The convective part is discretized by the local Lax-Friedrichs fluxes and the viscous part by the symmetric interior penalty method. Within the simple algorithm, the equations are solved in an iterative process. The discretized equations are linearized and an equation for the pressure is derived on the discrete level. The equations obtained for each velocity component and the pressure are decoupled and therefore can be solved sequentially, leading to an efficient solution procedure. The extension of the proposed scheme to the unsteady case is straightforward, where fully implicit time schemes can be used. Various test cases are carried out: the Poiseuille flow, the channel flow with constant transpiration, the Kovasznay flow, the flow into a corner and the backward-facing step flow. Using a mixed-order formulation, i.e. order k for the velocity and order k - 1 for the pressure, the scheme is numerically stable for all test cases. Convergence rates of k + 1 and k in the L-2-norm are observed for velocity and pressure, respectively. A study of the convergence behavior of the simple algorithm shows that no under-relaxation for the pressure is needed, which is in strong contrast to the application of the simple algorithm in the context of the finite volume method or the continuous finite element method. We conclude that the proposed scheme is efficient to solve the steady incompressible Navier-Stokes equations in the context of the discontinuous Galerkin method comprising hp-accuracy. (c) 2012 Elsevier Inc. All rights reserved.

关键词： Finite element methods Discontinuous Galerkin methods Navier-Stokes equations Incompressible flows Segregated solution algorithms simple algorithm

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