Namelist "HomeData_PoissonSolver"

This namelist contains all parameters on the iterative solvers and the nV-cycle multigrid method directly implemented in the code for solving the Poisson's equation (“homemade” development). The iterative solvers are based on the Successive Over Relaxation methods (SOR).

These data are only associated with the SOR-type solvers directly implemented in the code (“homemade” development) These data are taken into account only when the variable “Poisson_NumericalMethod” in the Namelist “Numerical_Methods” is correctly set (see Numerical_Methods (new version)). Poisson_NumericalMethod= Home-Multigrid-ConstantMatrixCoef Poisson_NumericalMethod= Home-Multigrid-VariableMatrixCoef Not for the release SUNFLUIDH_EDU

Full data set of the namelist

&HomeData_PoissonSolver SolverName="SOR-Redblack-MPI",
Number_max_Grid= 5,
Number_max_Cycle= 10,
Number_Iteration= 0,
Number_Iteration_FineToCoarseGrid= 1,
Number_Iteration_CoarseToFineGrid= 5,
Number_Iteration_CoarsestGrid= 10 ,
Relaxation_Coefficient= 1.7 ,
Convergence_Criterion= 1.D-15,
Off_Set_Poisson_Source_term= .false. /

Following the problem treated, some numerical methods are better adapted than others, this point is precised for each available option.

Definition of the data set

SolverName

Type: Character string

Selection of the iterative solver coupled with the multigrid method.

Jacobi : Successive Over Relaxed solver based on the Jacobi's method

SOR : Successive Over Relaxed solver based on the Gauss-Seidel method

SOR-Redblack : Successive Over Relaxed solver based on a “Red-Black” algorithm (useful with OpenMP-parallel computations)

SOR-Redblack-MPI : Successive Over Relaxed solver based on a “Red-Black” algorithm optimized for the domain decomposition approach (MPI-parallel computations)

Number_max_Grid (multigrid method only)

Type : Integer value

Maximum number of grid levels used in the multigrid method.

Number_max_Cycle (multigrid method only)

Type : Integer value

Maximum number of V-cycles permitted in the multigrid method.

Number_Iteration (only if the SOR method is used)

Type : integer value

Number of iterations performed by the SOR method in order to approach the solution on each grid level. This value is the same for any grid level of the Multigrid procedure.

Number_Iteration_FineToCoarseGrid (only if the SOR method is used)

Type : integer value

Number of iterations performed by the SOR solver during the restriction step of each V-cycle of the multigrid procedure. For some problems, the minimization of iterations during the restriction step can improve the time-performance of the code.
BEWARE : this data is enabled only if the variable Number_Iteration= 0 or is removed from the Namelist.

Number_Iteration_CoarsestGrid (only if the SOR method is used)

Type : integer value

Number of iterations performed by the SOR solver on the coarsest grid of each V-cycle of the multigrid procedure.
BEWARE : this data is enabled only if the variable Number_Iteration= 0 or is removed from the Namelist.

Number_Iteration_CoarseToFineFGrid (only if the SOR method is used)

Type : integer value

Number of iterations performed by the SOR solver during the prolongation step of each V-cycle of the multigrid procedure.
BEWARE : this data is enabled only if the variable Number_Iteration= 0 or is removed from the Namelist.

Relaxation_Coefficient (only if the SOR method is used)

Type : real value between one and two

over-relaxation coefficient used in the SOR method.

Convergence_Criterion (only if the SOR method is used)

Type : real value

The nV-cycle procedure of the multigrid method is stopped if the L2-norm of the Poisson equation's residu is lower than the criterion chosen.

Off_Set_Poisson_Source_term

Type : Boolean value. Not for the release SUNFLUIDH_EDU.

The source term is shifted from its averaged value such as its integral value over the domain is zero. This could facilitate the convergence in some particuliar cases. this option must be used with caution. For expert users only.