NOX Preconditioner Reuse

The optional Reuse Preconditioner sublist configures the preconditioner-reuse observer installed by Vertex-CFD.

<Reuse Preconditioner>

This optional sublist enables the NOX preconditioner-reuse observer installed by Vertex-CFD. At least one update trigger must be enabled, and the configured linear solver must provide a preconditioner.

Update prec at start of nonlinear solve
Type:

bool

Value:

true or false

Usage:

Optional

Default:

true

Description:

Rebuilds the preconditioner at nonlinear iteration zero of every solve.

Update prec after this many nonlinear solves
Type:

integer

Value:

Positive interval; zero or negative disables

Usage:

Optional

Default:

0

Description:

Rebuilds the preconditioner at the start of every specified number of nonlinear solves.

Reset nonlinear solve count on failed solve
Type:

bool

Value:

true or false

Usage:

Optional

Default:

true

Description:

Resets the nonlinear-solve interval counter when a solve fails. This entry applies when periodic updates by nonlinear-solve count are enabled.

Update prec after this many nonlinear iterations
Type:

integer

Value:

Positive interval; zero or negative disables

Usage:

Optional

Default:

0

Description:

Rebuilds the preconditioner at the specified nonlinear-iteration interval.

Update prec after this many stalled linear solves
Type:

integer

Value:

Positive count; zero or negative disables

Usage:

Optional

Default:

0

Description:

Rebuilds the preconditioner after this many consecutive stalled linear solves. A failed linear solve also triggers an update.

Max linear iterations for stall
Type:

integer

Value:

Linear-iteration threshold

Usage:

Optional when stalled-linear-solve updates are enabled

Default:

50

Description:

Declares a linear solve stalled when its iteration count reaches this threshold.

Example

Listing 21 Rebuild the preconditioner at every solve and after every two nonlinear solves.
1          <ParameterList name="Reuse Preconditioner">
2            <Parameter name="Update prec at start of nonlinear solve" type="bool" value="true"/>
3            <Parameter name="Update prec after this many nonlinear solves" type="int" value="2"/>
4          </ParameterList> <!-- Reuse Preconditioner -->