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Dorodnicyn, L.W. (author)The previous theory of artificial boundary conditions in gas dynamics has been elaborated mostly for the Euler equations. However, in practice, such boundary treatments are applied to discrete methods to solution of gasdynamic problems. In this study, based on exact nonreflecting boundary conditions for the 1D linearized Euler equations, we...conference paper 2006
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Wienands, R. (author)Solving discrete boundary value problems with the help of an appropriate multigrid method [1, 3, 4, 5] necessitates the construction of a sequence of coarse grids with corresponding coarse grid approximations for the given fine grid discretization. Popular choices in this context are the Galerkin coarse grid approximation (GCA) and the use of...conference paper 2006
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Köstler, H. (author), Popa, C. (author), Prümmer, M. (author), Rüde, U. (author)In this paper we introduce a multigrid method for sparse, possibly rank-deficient and inconsistent least squares problems arising in the context of tomographic image reconstruction. The key idea is to construct a suitable AMG method using the Kaczmarz algorithm as smoother. We first present some theoretical results about the correction step and...conference paper 2006
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Bernacki, M. (author), Piperno, S. (author)We present in this paper a time-domain Discontinuous Galerkin dissipation-free method for the transient solution of the three-dimensional linearized Euler equations around a steady-state solution. In the general context of a non-uniform supporting flow, we prove, using the well-known symmetrization of Euler equations, that some aeroacoustic...conference paper 2006
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Idelsohn, S.R. (author), Onate, E. (author), Marti, J. (author), Celigueta, M.A. (author), Limache, A. (author)We present a general formulation for analysis of fluid-structure interaction problems using the particle finite element method (PFEM). The key feature of the PFEM is the use of an updated Lagrangian description to model the motion of nodes (particles) in both the fluid and the structure domains. Nodes are viewed as material points (called...conference paper 2006
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Greaves, D.M. (author)This work involves the application of adaptive hierarchical grids to free surface Navier-Stokes simulation of viscous waves in a stationary tank and their interaction with a cylinder. Adapting quadtree grids are combined with a volume of fluid (VoF) approach, in which a high resolution interface capturing scheme is used for advection of the...conference paper 2006
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Yakovenko, S.N. (author), Chang, K.C. (author)In the present study, the surface tension is introduced as volume forces according to the continuum surface force (CSF) model [1] using the surface tension coefficient and the mollified volume fraction (color) function. The latter can be taken in the first approximation as the volume fraction defined numerically due to (possible) smoothing of...conference paper 2006
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Geurts, B.J. (author)Non-uniform filtering of the Navier-Stokes equations expresses itself, next to the turbulent stresses, in additional closure terms known as commutator errors. These terms require explicit subgrid modeling if the non-uniformity of the filter is sufficiently pronounced. We derive expressions for the magnitude of the mean flux, the turbulent stress...conference paper 2006
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Ito, K. (author), Toivanen, J. (author)The time-harmonic acoustic scattering in multi-layered media is modeled with an inhomogeneous Helmholtz equation for the pressure field. For example, such problems result from acoustic geological surveys. The exterior problem is truncated into a rectangle and an absorbing boundary condition is posed on its boundaries. A low-order finite...conference paper 2006
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Trias, F.X. (author), Soria, M. (author), Oliva, A. (author), Verstappen, R.W.C.P. (author)Since direct numerical simulations (DNS) of natural convection in a differentially heated cavity can not be performed at high Ra-numbers, a dynamically less complex mathematical formulation is sought. In the quest for such a formulation, we consider regularizations (smooth approximations) of the nonlinearity. The regularization method basically...conference paper 2006
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Arioli, M. (author), Loghin, D. (author)Abstract only.conference paper 2006
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Titarev, V.A. (author)Model kinetic equations are often used to describe rarefied gas flows in the broad range of flow regimes. Accurate model kinetic equations were proposed by Shakhov [1] for monatomic gases and by Rykov [2] for diatomic gases. The main advantage of these model equations over other models reported in the literature is that the model collision...conference paper 2006
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Blanquet, E. (author), Chaussende, D. (author), Nishizawa, S. (author), Pons, M. (author)Over the last twenty years, processes which lead to materials synthesis from a gaseous phase constitute an important technology in many applications fields such as microelectronics or protective coating industry. Due to the complexity of the involved phenomena, computational modeling had been required to improve technological processes and help...conference paper 2006
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Augarde, C.E. (author), Ramage, A. (author), Staudacher, J. (author)Abstract only.conference paper 2006
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Moura Neto, F.D. (author), Goncalves, F. (author)This work presents some results concerning the interface evolution of two imiscible fluids flowing inside an isotropic porous medium in a typical viscous instability problem, known as the Saffman-Taylor instability. This involves the application of an iterative parallelizable graph based algorithm coupled with a semi-Lagrangian level set...conference paper 2006
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SenthilKumar, S. (author), Delauré, Y.M.C. (author)A Volume of Fluid (VOF)-Youngs model for the solution of an incompressible immiscible two-phase flows is presented. The solver computes the flow field by solving the family of Navier Stokes equations using SIMPLE algorithm and tracks the position of interface between two fluids with different fluid properties by Piecewise Linear Interface...conference paper 2006
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Lüddeke, H. (author), Calvo, J.B. (author), Filimon, A. (author)Substantial requirements for future rocket technologies are the cost-efficient access to orbit as well as the increase in the system reliability. Concerning these requirements the engine is one of the most important parts and a deeper insight into the unsteady phenomena during the start phase of modern launchers is essential. Especially unsteady...conference paper 2006
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Turkel, E. (author), Erlangga, Y.A. (author)We consider acoustic scattering about a general body. This is described by the Helmholtz equation exterior to the body. In order to truncate the infinite domain we use the BGT absorbing boundary condition. The resultant problem in a finite domain is solved by a finite element procedure. This yields a large sparse system of linear equations which...conference paper 2006
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Schroeder, G. (author), Schlünzen, K.H. (author)In this work numerical dispersion relations for atmospheric gravity waves are experimentally analyzed using the anelastic mesoscale model METRAS. The dependency of the group velocity on grid size and advection scheme (central scheme (CDF) and methods based on the essentially non-oscillatory (ENO) method) is presented showing a retardation of the...conference paper 2006
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Vigneron, D. (author), Deliége, G. (author), Essers, J.A. (author)This paper presents a density-based finite volumes method for solving the unsteady Navier-Stokes equations on 3D unstructured grids. The second order Crank-Nicolson scheme is applied to perform the time integration. At each time step, the system of non linear equations is solved by means of a fully implicit dual time stepping method. An...conference paper 2006