7.19. CDFEM Options

This section is referenced in the following other sections

7.19.1. Cdfem Options

Scope

Aria Region

Summary

Main block for setting CDFEM options.

Description

This block is where CDFEM options that apply to all CDFEM interfaces in a problem (level sets, CDFEM death, CDFEM isosurfaces, and CDFEM irreversible phase change) can be set. These options include the edge degeneracy handling method, edge tolerance, prolongation model, etc.

begin Cdfem Options

   Cdfem Dof Edge Tolerance {=} Value

   Cdfem Edge Degeneracy Handling {=} {snap_to_interface_when_quality_allows_then_snap_to_node | snap_to_node}

   Cdfem Edge Tolerance {=} Value

   Cdfem Element Size {=} {conformal | nonconformal}

   Cdfem Internal Side Stabilization [ Multiplier {=} Multiplier  ]

   Cdfem Nonconformal Adaptivity Levels {=} Value

   Cdfem Prolongation Model {=} {ale_nearest_node | ale_nearest_point | interpolation}

   Cdfem Simplex Generation Method {=} {cut_quads_by_global_identifier | cut_quads_by_largest_angle, | cut_quads_by_nearest_edge_cut}

   Constrain Cdfem To Xfem Space {=} {false | no | off | on | true | yes}

   Initial Prolongation Field For DestFieldName {=} SrcFieldName

   Length Scale For Interface Courant Limit {=} {constant | l1_norm | local} [ Value {=} ConstantLengthScaleVelue  ]

   Levelset Refinement Interval {=} interval1 interval2

   Max Edge Snap {=} value

   Nonconformal Adaptivity Target Element Count {=} Value

   Number Of Initial Decomposition Cycles {=} Value

   Perform Volume Correction After Levelset Solve {=} {false | no | off | on | true | yes}

   Preserve Sharp Features When Snapping [ Feature_Angle {=} Angle  ]

   Prolongate Additional Fields {=} FieldNames...

   Resnap Mesh Using Interface On Previous Snapped Mesh {=} {false | no | off | on | true | yes}

   Resnap Mesh Using Interpolation {=} {false | no | off | on | true | yes}

   Use Ale Prolongation For FieldName

   Use Hierarchical Dofs {=} {false | no | off | on | true | yes}

   Use Interpolation To Unsnap Mesh {=} {false | no | off | on | true | yes}

   Use Velocity To Evaluate Interface Courant Limit {=} {false | no | off | on | true | yes}

end Cdfem Options

7.19.1.1. Line Commands

Cdfem Dof Edge Tolerance

Syntax

Cdfem Dof Edge Tolerance {=} Value

Summary

Specify the tolerance used to “snap” the DOFs to the edge node values on CDFEM meshes.

Parameter

Value

Default

{=}

{= | are | is}

–

Value

real

0.0

Cdfem Edge Degeneracy Handling

Syntax

Cdfem Edge Degeneracy Handling {=} {snap_to_interface_when_quality_allows_then_snap_to_node | snap_to_node}

Summary

Specify the strategy for handling edges that are cut very close to a node.

Parameter

Value

Default

{=}

{= | are | is}

–

CDFEMEdgeDegeneracyHandlingType

{snap_to_interface_when_quality_allows_then_snap_to_node | snap_to_node}

GLOBAL_SNAP_TO_NODE

Cdfem Edge Tolerance

Syntax

Cdfem Edge Tolerance {=} Value

Summary

Specify the tolerance used to “snap” the CDFEM conformal interface to the nonconformal mesh.

Parameter

Value

Default

{=}

{= | are | is}

–

Value

real

1.0e-3

Cdfem Element Size

Syntax

Cdfem Element Size {=} {conformal | nonconformal}

Summary

Specify whether the element size is based on CONFORMAL OR NONCONFORMAL element (used for pressure stabilization).

Parameter

Value

Default

{=}

{= | are | is}

–

CDFEMElementSize

{conformal | nonconformal}

NONCONFORMAL

Cdfem Internal Side Stabilization

Syntax

Cdfem Internal Side Stabilization [ Multiplier {=} Multiplier ]

Summary

Turn on internal face stabilization on equations that support it, optionally specifying a multiplier (default = 1.0).


Cdfem Nonconformal Adaptivity Levels

Syntax

Cdfem Nonconformal Adaptivity Levels {=} Value

Summary

Specify the number of levels of non-conformal adaptivity that should be performed before the conformal decomposition is performed.

Parameter

Value

Default

{=}

{= | are | is}

–

Value

integer

0

Cdfem Prolongation Model

Syntax

Cdfem Prolongation Model {=} {ale_nearest_node | ale_nearest_point | interpolation}

Summary

Specify the strategy for prolonging nodes created by conformal decomposition.

Parameter

Value

Default

{=}

{= | are | is}

–

CDFEMEProlongationModelType

{ale_nearest_node | ale_nearest_point | interpolation}

ALE_NEAREST_NODE

Cdfem Simplex Generation Method

Syntax

Cdfem Simplex Generation Method {=} {cut_quads_by_global_identifier | cut_quads_by_largest_angle, | cut_quads_by_nearest_edge_cut}

Summary

Specify how the quadrilateral elements (2D) or quadrilateral faces (3D) that are generated by the conformal decomposition process are subdivided into triangles. Default: For 2D: CUT_QUADS_BY_LARGEST_ANGLE, For 3D: CUT_QUADS_BY_NEAREST_EDGE_CUT

Parameter

Value

Default

{=}

{= | are | is}

–

CDFEMSimplexGenerationMethod

{cut_quads_by_global_identifier | cut_quads_by_largest_angle, | cut_quads_by_nearest_edge_cut}

–

Constrain Cdfem To Xfem Space

Syntax

Constrain Cdfem To Xfem Space {=} {false | no | off | on | true | yes}

Summary

Specify whether the CDFEM DOFs should be constrained to the coarser XFEM discrete space. Default = FALSE.

Parameter

Value

Default

{=}

{= | are | is}

–

constrainCDFEMtoXFEM

{false | no | off | on | true | yes}

FALSE

Initial Prolongation Field For

Syntax

Initial Prolongation Field For DestFieldName {=} SrcFieldName

Summary

Specifies that the field DestFieldName will use the field SrcFieldName for prolongation if (no prolongation node is found OR DestFieldName is not defined on the prolongation node) AND DestFieldName was not defined on the node at the last time step. For example this could be used in a foam decomposition problem where no fluid region is initially present, but one appears as the foam decomposes and the fluid field values should be populated based on the foam field values, e.g. INITIAL PROLONGATION FIELD FOR solution->pressure is solution->gas_phase_pressure

Parameter

Value

Default

DestFieldName

string

–

{=}

{= | are | is}

–

SrcFieldName

string

–

Length Scale For Interface Courant Limit

Syntax

Length Scale For Interface Courant Limit {=} {constant | l1_norm | local} [ Value {=} ConstantLengthScaleVelue ]

Summary

Specify how the length scale is computed in the Interface CFL calculation. If CONSTANT is specified then the value is also given via VALUE=NNN. If L1_NORM is specified, the average element size across the conforming interfaces is used. Default is LOCAL, meaning that the local element size is used.

Parameter

Value

Default

{=}

{= | are | is}

–

InterfaceCFLLengthScaleType

{constant | l1_norm | local}

–

Levelset Refinement Interval

Syntax

Levelset Refinement Interval {=} interval1 interval2

Summary

Use this command to specify the range of level set values that should be fully refined. If this is not specified, the elements that span the zero level set are refined.

Parameter

Value

Default

{=}

{= | are | is}

–

interval

real1 real2

–

Max Edge Snap

Syntax

Max Edge Snap {=} value

Summary

Use this command to specify the largest relative snap that should be performed on cut edges. If this is not specified, any size edge snap is allowed (default = 1.0).

Parameter

Value

Default

{=}

{= | are | is}

–

value

real

–

Nonconformal Adaptivity Target Element Count

Syntax

Nonconformal Adaptivity Target Element Count {=} Value

Summary

Specify a target element count for the nonconformal adaptivity. This will cause the non-conformal adaptivity to use at most “CDFEM NONCONFORMAL ADAPTIVITY LEVELS” levels of refinement of a given parent element and will only refine as elements until the target element count is reached instead of refining all elements cut by the interface. At present this capability only works with analytic initial conditions in krino.

Parameter

Value

Default

{=}

{= | are | is}

–

Value

real

0

Number Of Initial Decomposition Cycles

Syntax

Number Of Initial Decomposition Cycles {=} Value

Summary

Specify the number of times the mesh is decomposed and the fields are (re)initialized. Repeated decomposition and initialization improves the accuracy of the interface location because the added nodes are also initialized.

Parameter

Value

Default

{=}

{= | are | is}

–

Value

integer

1

Perform Volume Correction After Levelset Solve

Syntax

Perform Volume Correction After Levelset Solve {=} {false | no | off | on | true | yes}

Summary

Use this command to specify whether interpolation should be used to unsnap the mesh. Default is false (in which case ALE is used in aria).

Parameter

Value

Default

{=}

{= | are | is}

–

flag

{false | no | off | on | true | yes}

–

Preserve Sharp Features When Snapping

Syntax

Preserve Sharp Features When Snapping [ Feature_Angle {=} Angle ]

Summary

When snapping the mesh to the interface, respect sharp features, optionally specifying the FEATURE ANGLE in degrees (default = 135.).


Prolongate Additional Fields

Syntax

Prolongate Additional Fields {=} FieldNames…

Summary

Use this command to add additional fields to be prolongated in CDFEM problems (this prolongation is a nearest point projection).

Parameter

Value

Default

{=}

{= | are | is}

–

FieldNames

string…

–

Resnap Mesh Using Interface On Previous Snapped Mesh

Syntax

Resnap Mesh Using Interface On Previous Snapped Mesh {=} {false | no | off | on | true | yes}

Summary

Use this command to specify whether mesh resnapped using interface location on previous snapped mesh. Default is false (in which case ALE unsnap or INTERPOLATION unsnap is used instead in aria).

Parameter

Value

Default

{=}

{= | are | is}

–

flag

{false | no | off | on | true | yes}

–

Resnap Mesh Using Interpolation

Syntax

Resnap Mesh Using Interpolation {=} {false | no | off | on | true | yes}

Summary

Use this command to specify whether mesh resnapped using interpolation from the solution on the previous snapped mesh. Default is currently false (in which case ALE unsnap is used instead in aria).

Parameter

Value

Default

{=}

{= | are | is}

–

flag

{false | no | off | on | true | yes}

–

Use Ale Prolongation For

Syntax

Use Ale Prolongation For FieldName

Summary

WARNING: Use cases for this line command are VERY rare.

Force the use of ALE prolongation for the field specified by FieldName.

Parameter

Value

Default

FieldName

string

–

Use Hierarchical Dofs

Syntax

Use Hierarchical Dofs {=} {false | no | off | on | true | yes}

Summary

Specify whether the CDFEM DOFs should be transformed to hierarchical unknowns. This can significantly improve the performance of iterative solvers, especially in parallel. Default = FALSE.

Parameter

Value

Default

{=}

{= | are | is}

–

useHierarchicalDofs

{false | no | off | on | true | yes}

FALSE

Use Interpolation To Unsnap Mesh

Syntax

Use Interpolation To Unsnap Mesh {=} {false | no | off | on | true | yes}

Summary

Use this command to specify whether interpolation should be used to unsnap the mesh. Default is false (in which case ALE is used in aria).

Parameter

Value

Default

{=}

{= | are | is}

–

flag

{false | no | off | on | true | yes}

–

Use Velocity To Evaluate Interface Courant Limit

Syntax

Use Velocity To Evaluate Interface Courant Limit {=} {false | no | off | on | true | yes}

Summary

Specify whether the Interface Courant Limit should be calculated using the velocity on the interface. If true, the CFL is calculated using the normal of solution->Velocity field on the CDFEM interfaces. If false, the CFL is calculated using the CDFEM Mesh Displacements on the CDFEM interfaces. Default = FALSE.

Parameter

Value

Default

{=}

{= | are | is}

–

useVelocityToEvaluateInterfaceCFL

{false | no | off | on | true | yes}

FALSE