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Flux Boundary Conditions (flux + boundary_condition)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

The lattice Boltzmann method and the finite volume method applied to conduction,radiation problems with heat flux boundary conditions

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2009
Bittagopal Mondal
Abstract This article deals with the implementation of the lattice Boltzmann method (LBM) in conjunction with the finite volume method (FVM) for the solution of conduction,radiation problems with heat flux and temperature boundary conditions. Problems in 1-D planar and 2-D rectangular geometries have been considered. The radiating,conducting participating medium is absorbing, emitting and scattering. In the 1-D planar geometry, the south boundary is subjected to constant heat flux, while in the 2-D geometry the south and/or the north boundary is at constant heat flux condition. The remaining boundaries are at prescribed temperatures. The energy equation is solved using the LBM and the radiative information for the same is computed using the FVM. In the direct method, by prescribing temperatures at the boundaries, the temperature profile and heat flux are calculated. The computed heat flux values are imposed at the boundaries to establish the correctness of the numerical code in the inverse method. Effects of various parameters such as the extinction coefficient, the scattering albedo, the conduction,radiation parameter, the boundary emissivity and the total heat flux and boundary temperatures are studied on the distributions of temperature, radiative and conductive heat fluxes. The results of the LBM in conjunction with the FVM have been found to compare very well with those available in the literature. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Parallelization of a vorticity formulation for the analysis of incompressible viscous fluid flows

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2002
Mary J. Brown
Abstract A parallel computer implementation of a vorticity formulation for the analysis of incompressible viscous fluid flow problems is presented. The vorticity formulation involves a three-step process, two kinematic steps followed by a kinetic step. The first kinematic step determines vortex sheet strengths along the boundary of the domain from a Galerkin implementation of the generalized Helmholtz decomposition. The vortex sheet strengths are related to the vorticity flux boundary conditions. The second kinematic step determines the interior velocity field from the regular form of the generalized Helmholtz decomposition. The third kinetic step solves the vorticity equation using a Galerkin finite element method with boundary conditions determined in the first step and velocities determined in the second step. The accuracy of the numerical algorithm is demonstrated through the driven-cavity problem and the 2-D cylinder in a free-stream problem, which represent both internal and external flows. Each of the three steps requires a unique parallelization effort, which are evaluated in terms of parallel efficiency. Copyright © 2002 John Wiley & Sons, Ltd. [source]

One-level Newton,Krylov,Schwarz algorithm for unsteady non-linear radiation diffusion problem

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 10 2004
Serguei Ovtchinnikov
Abstract In this paper, we present a parallel Newton,Krylov,Schwarz (NKS)-based non-linearly implicit algorithm for the numerical solution of the unsteady non-linear multimaterial radiation diffusion problem in two-dimensional space. A robust solver technology is required for handling the high non-linearity and large jumps in material coefficients typically associated with simulations of radiation diffusion phenomena. We show numerically that NKS converges well even with rather large inflow flux boundary conditions. We observe that the approach is non-linearly scalable, but not linearly scalable in terms of iteration numbers. However, CPU time is more important than the iteration numbers, and our numerical experiments show that the algorithm is CPU-time-scalable even without a coarse space given that the mesh is fine enough. This makes the algorithm potentially more attractive than multilevel methods, especially on unstructured grids, where course grids are often not easy to construct. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Landscape memory: the imprint of the past on contemporary landscape forms and processes

AREA, Issue 1 2010
Gary John Brierley
The imprint of the past upon contemporary landscape forms and processes is differentiated in terms of geologic, climatic and anthropogenic memory. Geologic memory refers to controls exerted upon relief, erodibility, erosivity and accommodation space (areas in landscapes where sediments are stored and reworked). These factors set the imposed boundary conditions within which contemporary landscape-forming processes operate. Climatic memory refers to the influence of past climatic conditions upon contemporary landscape forms and processes. Climatic controls exert a primary influence upon the nature of geomorphic processes, while the influence of climate upon ground cover affects the effectiveness of these processes. Climate change may induce profound alterations to the flux boundary conditions under which contemporary landscapes operate. This is exemplified by the variable imprint of glacial/interglacial cycles in differing parts of the world. Anthropogenic memory refers to the imprint of past human activities on contemporary landscapes, whereby human disturbance in the past altered landscape forms, processes and associated flow/sediment fluxes in a manner that continues to affect the way the contemporary landscape works. Contrasting examples from a tectonically stable landscape (Australia) and a tectonically uplifting landscape (New Zealand) are used to highlight the variable influence of geologic, climatic and anthropogenic memory upon the persistence and erasure of landscape forms and resulting implications for sediment flux in differing settings. [source]