# 7.29. Level Set

This section is referenced in the following other sections

- Simulation Setup: Level Set/CDFEM

## 7.29.1. Level Set Interface

Scope

  Aria Region

Summary

  Main block for krino level set interface control mechanics.

Description

  This is the main block for the level set interface control mechanics. This block specifies a level set interface that is integrated in time using an extension velocity. The plan is that the physics application code will see only this mechanics, although there may be several other supporting mechanics that are plugged in.

    begin Level Set Interface InterfaceName

       Composite Name {=} Variable

       Distance Variable {=} Variable

       Initial Offset Distance {=} Offset

       Initial Scale Factor {=} Scale

       Max Feature Size On Surfaces {=} Value

       Narrow Band Element Size Multiplier {=} Value

       Narrow Band Width {=} Value

       Perform Initial Redistance {=} {false | no | off | on | true | yes}

       Redistance Method {=} {closest_point | fast_marching}

       Reinitialize Every Step

       Simple Max Feature Size On Surfaces {=} Value

       begin Analytic Initial Condition BlockName
       end

       begin Compute_Surface_Distance SurfaceName
       end

       begin Motion Specification Motion
       end

    end Level Set Interface InterfaceName

### 7.29.1.1. Line Commands

###### Composite Name

Syntax

  Composite Name {=} Variable

Summary

  Optionally specify a composite level set name which may be used across multiple level sets to define composite phases.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Variable | string | –

###### Distance Variable

Syntax

  Distance Variable {=} Variable

Summary

  Specify the distance variable name.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Variable | string | –

###### Initial Offset Distance

Syntax

  Initial Offset Distance {=} Offset

Summary

  Specify an offset distance to be applied to the initial level set. Allows the user to grow or shrink the initialized level set.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Offset | real | –

###### Initial Scale Factor

Syntax

  Initial Scale Factor {=} Scale

Summary

  Specify an scale factor to be applied to the initial level set. Allows the user to multiple the entire level set by a constant, primarily useful for nested (concentric) level sets. This modifier gets applied after the INITIAL OFFSET DISTANCE, if there is one.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Scale | real | –

###### Max Feature Size On Surfaces

Syntax

  Max Feature Size On Surfaces {=} Value

Summary

  Specify the maximum feature size on surfaces, features smaller than this will be destroyed near all surfaces. IN BETA TESTING!

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Value | real | –

###### Narrow Band Element Size Multiplier

Syntax

  Narrow Band Element Size Multiplier {=} Value

Summary

  Specify the width of the narrow band width used for the level set field as the given multiplier times the maximum element length scale. If this command is omitted, the distance will be computed throughout the entire domain, but this is not generally scalable in terms of memory or cpu time.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Value | real | –

###### Narrow Band Width

Syntax

  Narrow Band Width {=} Value

Summary

  Specify the width of the narrow band. This form is deprecated. Use NARROW BAND ELEMENT SIZE MULTIPLIER instead.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Value | real | –

###### Perform Initial Redistance

Syntax

  Perform Initial Redistance {=} {false | no | off | on | true | yes}

Summary

  Perform redistancing operation just after initial conditions are applied.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
performInitialRedistance | {false | no | off | on | true | yes} | FALSE

###### Redistance Method

Syntax

  Redistance Method {=} {closest_point | fast_marching}

Summary

  Specify the algorithm to be used for redistancing.

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
RedistanceMethodType | {closest_point | fast_marching} | CLOSEST_POINT

###### Reinitialize Every Step

Syntax

  Reinitialize Every Step

Summary

  Specify that this level set interface should be re-initialized every time step. For example this can be combined with an analytic mesh surface initial condition that is moving due to applied displacements to move the CDFEM interface location with the mesh surface.

###### Simple Max Feature Size On Surfaces

Syntax

  Simple Max Feature Size On Surfaces {=} Value

Summary

  Specify the maximum feature size on surfaces, features smaller than this will be destroyed near all surfaces (simple version) IN BETA TESTING!

Parameter | Value | Default
--- | --- | ---
{=} | {= | are | is} | –
Value | real | –