# Compute Surface Tension KKS

Surface tension of an interface defined by the gradient of an order parameter

## Description

This material generates a surface tension tensor in the interface between two phases in the Kim-Kim-Suzuki (KKS) phase-field model (Kim et al. (1999)). The surface tension consists of two orthogonal principal components lying in plane of the interface. The approach is based on the formulation described in Levitas and Samani (2011). (For solid surfaces where the surface stress is to be specifed rather than surface tension, use the ComputeInterfaceStress kernel instead.)

The surface tension tensor is given by (1) where is the free energy barrier between phases, is the double-well function, is the order parameter, is the gradient energy coefficient, is the identity tensor, and denotes the dyadic product.

## Example Input File Syntax

[./interface_stress]
type = ComputeSurfaceTensionKKS
v = eta
kappa_name = kappa
w = 0.0033
[../]

(modules/combined/test/tests/surface_tension_KKS/surface_tension_KKS.i)

## Input Parameters

• wDouble well height parameter

C++ Type:double

Options:

Description:Double well height parameter

### Required Parameters

• computeTrueWhen false, MOOSE will not call compute methods on this material. The user must call computeProperties() after retrieving the Material via MaterialPropertyInterface::getMaterial(). Non-computed Materials are not sorted for dependencies.

Default:True

C++ Type:bool

Options:

Description:When false, MOOSE will not call compute methods on this material. The user must call computeProperties() after retrieving the Material via MaterialPropertyInterface::getMaterial(). Non-computed Materials are not sorted for dependencies.

• ggBarrier Function Material that provides g(eta)

Default:g

C++ Type:MaterialPropertyName

Options:

Description:Barrier Function Material that provides g(eta)

Default:kappa_op

C++ Type:MaterialPropertyName

Options:

• planar_stress_nameextra_stressMaterial property name for the interfacial planar stress

Default:extra_stress

C++ Type:MaterialPropertyName

Options:

Description:Material property name for the interfacial planar stress

• vOrder parameter that defines the interface, assumed to vary from 0 to 1.

C++ Type:std::vector

Options:

Description:Order parameter that defines the interface, assumed to vary from 0 to 1.

• boundaryThe list of boundary IDs from the mesh where this boundary condition applies

C++ Type:std::vector

Options:

Description:The list of boundary IDs from the mesh where this boundary condition applies

• blockThe list of block ids (SubdomainID) that this object will be applied

C++ Type:std::vector

Options:

Description:The list of block ids (SubdomainID) that this object will be applied

### Optional Parameters

• output_propertiesList of material properties, from this material, to output (outputs must also be defined to an output type)

C++ Type:std::vector

Options:

Description:List of material properties, from this material, to output (outputs must also be defined to an output type)

• outputsnone Vector of output names were you would like to restrict the output of variables(s) associated with this object

Default:none

C++ Type:std::vector

Options:

Description:Vector of output names were you would like to restrict the output of variables(s) associated with this object

### Outputs Parameters

• enableTrueSet the enabled status of the MooseObject.

Default:True

C++ Type:bool

Options:

Description:Set the enabled status of the MooseObject.

• use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

Default:False

C++ Type:bool

Options:

Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

• control_tagsAdds user-defined labels for accessing object parameters via control logic.

C++ Type:std::vector

Options:

Description:Adds user-defined labels for accessing object parameters via control logic.

• seed0The seed for the master random number generator

Default:0

C++ Type:unsigned int

Options:

Description:The seed for the master random number generator

• implicitTrueDetermines whether this object is calculated using an implicit or explicit form

Default:True

C++ Type:bool

Options:

Description:Determines whether this object is calculated using an implicit or explicit form

• constant_onNONEWhen ELEMENT, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps.When SUBDOMAIN, MOOSE will only call computeSubdomainProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped

Default:NONE

C++ Type:MooseEnum

Options:NONE ELEMENT SUBDOMAIN

Description:When ELEMENT, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps.When SUBDOMAIN, MOOSE will only call computeSubdomainProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped