“…The last term on the right hand side of Equation (52) is introduced to stabilize the incompressibility equation as discussed in [25]. The remaining stabilizing terms in Equations (52) and (53) can be derived by various techniques including a least squares procedure.…”
Section: A Stabilized Finite Element Scheme For the Momentum Equationsmentioning
confidence: 99%
“…where n en is the number of nodes in the element, N e α is the basis function associated with the local node α, and s is the unit vector in the direction of the local velocity [23,24,25]. The element h # on the other hand is defined to be the diameter of the circle which is area equivalent to the element.…”
Section: A Stabilized Finite Element Scheme For the Momentum Equationsmentioning
SUMMARYA stabilized equal-order velocity-pressure finite element algorithm is presented for the analysis of flow in porous media and in the solidification of binary alloys. The adopted governing macroscopic conservation equations of momentum, energy and species transport are derived from their microscopic counterparts using the volume-averaging method. The analysis is performed in a single-domain with a fixed numerical grid. The fluid flow scheme developed includes SUPG (streamline-upwind/PetrovGalerkin), PSPG (pressure stabilizing/Petrov-Galerkin) and DSPG (Darcy stabilizing/PetrovGalerkin) stabilization terms in a variable porosity medium. For the energy and species equations a classical SUPG-based finite element method is employed. The developed algorithms were tested extensively with bilinear elements and were shown to perform stably and with nearly quadratic convergence in high Rayleigh number flows in varying porosity media. Examples are shown in natural and double diffusive convection in porous media and in the directional solidification of a binary-alloy.
“…The last term on the right hand side of Equation (52) is introduced to stabilize the incompressibility equation as discussed in [25]. The remaining stabilizing terms in Equations (52) and (53) can be derived by various techniques including a least squares procedure.…”
Section: A Stabilized Finite Element Scheme For the Momentum Equationsmentioning
confidence: 99%
“…where n en is the number of nodes in the element, N e α is the basis function associated with the local node α, and s is the unit vector in the direction of the local velocity [23,24,25]. The element h # on the other hand is defined to be the diameter of the circle which is area equivalent to the element.…”
Section: A Stabilized Finite Element Scheme For the Momentum Equationsmentioning
SUMMARYA stabilized equal-order velocity-pressure finite element algorithm is presented for the analysis of flow in porous media and in the solidification of binary alloys. The adopted governing macroscopic conservation equations of momentum, energy and species transport are derived from their microscopic counterparts using the volume-averaging method. The analysis is performed in a single-domain with a fixed numerical grid. The fluid flow scheme developed includes SUPG (streamline-upwind/PetrovGalerkin), PSPG (pressure stabilizing/Petrov-Galerkin) and DSPG (Darcy stabilizing/PetrovGalerkin) stabilization terms in a variable porosity medium. For the energy and species equations a classical SUPG-based finite element method is employed. The developed algorithms were tested extensively with bilinear elements and were shown to perform stably and with nearly quadratic convergence in high Rayleigh number flows in varying porosity media. Examples are shown in natural and double diffusive convection in porous media and in the directional solidification of a binary-alloy.
“…A classical step-size controller is used for time step selection with maximum increase and decrease factors of two and one-tenth, respectively [69, p. 168]. For stabilized CG approximations, the evaluation of τ and ν c is lagged a time step after an initial startup phase in an effort to simplify the nonlinear solves [70]. ∆t is decreased by a factor of ten when a nonlinear solver failure is encountered.…”
“…with the help of element matrix and vector norms [24], the Green's function of the element [12], mathematical error analysis [4,5,16], or model equations [2,9,17].…”
Meshfree stabilised methods are employed and compared for the solution of the incompressible Navier-Stokes equations in Eulerian formulation. These PetrovGalerkin methods are standard tools in the FEM context, and can be used for meshfree methods as well. However, the choice of the stabilisation parameter has to be reconsidered. We find that reliable and successful approximation with standard formulas for the stabilisation parameter can only be expected for shape functions with small supports or dilatation parameters.
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