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COMSOL Multiphysics™

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femsolver<br />

TABLE 1-35: MULTIGRID SOLVERS PROPERTY/VALUE PAIRS<br />

PROPERTY VALUES DEFAULT DESCRIPTION<br />

mggeom vector of positive integers all Geometry<br />

numbers for<br />

multigrid<br />

hierarchy (gmg)<br />

mgkeep on | off off Keep generated<br />

mesh cases<br />

(gmg)<br />

mglevels integer>1 6 (amg), 2<br />

(gmg)<br />

postsmooth<br />

postsmoothpar<br />

presmooth<br />

presmoothpar<br />

ssor | ssoru | sor | soru<br />

| jac | ssorvec | sorvec<br />

| soruvec | gmres | cg |<br />

amg | vanka<br />

cell array with property/<br />

value pairs<br />

ssor | ssoru | sor | soru<br />

| jac | ssorvec | sorvec<br />

| soruvec | gmres | cg |<br />

amg | vanka<br />

cell array with property/<br />

value pairs<br />

soru<br />

Maximum<br />

number of<br />

multigrid levels<br />

Postsmoother<br />

{} Postsmoother<br />

properties<br />

sor<br />

Presmoother<br />

{} Presmoother<br />

properties<br />

rmethod regular | longest regular Mesh refinement<br />

method (gmg)<br />

shapechg vector of integers -1 Change in shape<br />

function orders<br />

(gmg)<br />

For the Geometric multigrid solver/preconditioners, the construction of the<br />

multigrid hierarchy is controlled by the properties Mgauto, Mcase, Mglevels,<br />

Meshscale, Shapechg, and Mgassem:<br />

• If Mgauto=both, shape, or meshscale, then the multigrid hierarchy is<br />

automatically constructed starting from the mesh case given in the property<br />

Mcase. This process is described in the section “Constructing a Multigrid<br />

Hierarchy” on page 423 in the <strong>COMSOL</strong> Multiphysics User’s Guide, where the<br />

methods are called Coarse mesh and lower order (both), Lower element order first<br />

(shape), and Coarse mesh (meshscale). The mesh coarsening factor is given in<br />

the scalar Meshscale, the shape function order change amount is given in the<br />

158 | CHAPTER 1: COMMAND REFERENCE

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