SOR Vector
The SOR Vector node () handles settings for the SOR vector iterative method. This is a method of SOR type with added functionality useful for electromagnetics problems involving the ∇ × (a∇ × .) curl-curl operator and where you use vector elements (available primarily for electromagnetic wave simulations in the RF Module). In short, the added functionality consists of performing SOR iterations on an auxiliary linear system in addition to the ordinary SOR iterations. This node can be used as preconditioner/smoother together with the Iterative, Krylov Preconditioner, Presmoother, Postsmoother, or Coarse Solver nodes. Also see The SOR Vector Algorithm.
Main
Settings When Used with Any Attribute Node
Use the Solver list to specify which variant of the SOR Vector algorithm to use. Select:
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SSOR vector to perform one ordinary SOR iteration on the main system followed by a number of SSOR iterations on an auxiliary (projected) system and then one ordinary SORU iteration. This is repeated in each SSOR vector iteration.
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SOR vector to perform one ordinary SOR iteration followed by a number of SOR iterations on an auxiliary system. This is repeated in each SOR vector iteration.
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SORU vector to perform a number of SORU iterations on an auxiliary system followed by one ordinary SORU iteration. This is repeated in each SORU vector iteration.
The algorithms perform these iterations to preserve symmetry as a preconditioner and also when used as symmetric presmoother and postsmoother in a multigrid setting.
Specify a scalar Relaxation factor ω. The allowed values of this factor are between 0 and 2 (default: 1). See About the Relaxation Factor for more information.
The Blocked version check box is selected by default and it uses a version of the SOR Vector method that is optimized for parallel computations.
Select the Reuse data check box (selected by default) to reuse the data in the blocks that define the SOR method. If you have selected that check box, the Reuse sparsity pattern check box is available. It is elected by default to store the sparsity patterns of the assembled matrices and try to reuse them for successive assembly processes within the same solution process. In many cases, the sparsity pattern of the system matrices does not change from one nonlinear iteration or time step to the others. Reusing the sparsity pattern from the previous iteration or step can then improve the solution performance at the cost of a usually small amount of memory.
Use the Variables list to specify variables to be included in the auxiliary system of the SOR Vector method.
Settings with and Without a Coarse Solver
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If used with a Coarse Solver, select a Termination technique. These are described for the SCGS attribute under Settings When Used With a Coarse Solver.
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If a Coarse Solver is not used, enter the Number of iterations to specify a fixed number of iterations to perform when this attribute is used as a preconditioner or smoother (default: 2). Then use the Number of secondary iterations field to specify the number of iterations to perform the auxiliary system for each main iteration (default: 1).