Mechanical APDL Basic Analysis Guide

memory parallelism on shared memory parallel hardware (e.g., a desktop or workstation) or distributed
memory parallel hardware (e.g., a cluster). MDOF indicat es million degrees of freedom.

Table 5.1: Shared Memory Solver Selection Guidelines

Disk

(I/O)

Use

Ideal Model Memory Use

Size

Solver Typical Applications

Op-

tim-

Optimal

out-of-

100,000 DOF

to 5 MDOF

When robustness and solution

speed are required (nonlinear ana-

Sparse Dir-

ect Solver

core: 1 al

GB/MDOF

(works well

outside this

range)

lysis); for linear analysis where iterat-

ive solvers are slow to converge

(especially for ill-conditioned

(direct elim-

ination) out-

of-

In-core:

10

GB/MDOF

matrices, such as poorly shaped

elements).

core:

10

GB/MDOF

In-

core:

1

GB/MDOF

0.5

GB/MDOF

0.3 GB/MDOF

w/MSAVE,ON;

500,000 DOF

to 20

MDOF+

Reduces disk I/O requirement relat-

ive to sparse solver. Best for large

models with solid elements and fine

PCG Solver

(iterative

solver) 1 GB/MDOF

meshes. Most robust iterative solver

in ANSYS.

without

MSAVE

0.5

GB/MDOF

500,000 DOF 0.5 GB/MDOF

to 20

MDOF+

Best for single field problems -

(thermal, magnetics, acoustics, and

multiphysics). Uses a fast but simple

JCG Solver

(iterative

solver)

preconditioner with minimal

memory requirement. Not as robust

as PCG solver.

0.5

GB/MDOF

50,000 to 1.5 GB/MDOF

1,000,000+

DOF

More sophisticat ed preconditioner

than JCG. Best for more difficult

problems where JCG fails, such as

unsymmetric thermal analyses.

ICCG Solver

(iterative

solver)

0.5

GB/MDOF

50,000 to 1.5 GB/MDOF

1,000,000+

DOF

QMR Solver High-frequency electromagnetics.

(iterative

solver)

Table 5.2: Distributed Memory Solver Selection Guidelines

Disk

(I/O)

Use

Ideal Model Memory Use

Size

Solver Typical Applications

Op-

tim-

Optimal

out-of-

500,000 DOF

to 10 MDOF

Same as sparse solver but can also

be run on distributed memory par-

allel hardware systems.

Distributed

Memory

Sparse Dir-

ect Solver

al

out-

core: 1.5

GB/MDOF

(works well

outside this

range) on mas- of-

ter ma- core:

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Solution