7.20. CDFEM Options

This section is referenced in the following other sections

Simulation Setup: Level Set/CDFEM

7.20.1. 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_closest_node | ale_closest_point | 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

7.20.1.1. 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_closest_node | ale_closest_point | 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_closest_node \| ale_closest_point \| ale_nearest_node \| ale_nearest_point \| interpolation}	ALE_CLOSEST_POINT

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