MomentumFreeSlipBC Class Reference

Boundary condition that applies free slip condition at nodes. More...

#include <MomentumFreeSlipBC.h>

Inheritance diagram for MomentumFreeSlipBC:

Public Member Functions
	MomentumFreeSlipBC (const InputParameters &parameters)
virtual	~MomentumFreeSlipBC ()
virtual bool	shouldApply () override

Protected Member Functions
virtual Real	computeQpResidual () override

Protected Attributes
const unsigned int	_mesh_dimension
	The dimension of the mesh. More...
const VariableValue &	_rho_u
	Momentum in x-direction. More...
const VariableValue &	_rho_v
	Momentum in y-direction. More...
const VariableValue &	_rho_w
	Momentum in z-direction. More...

Detailed Description

Boundary condition that applies free slip condition at nodes.

Definition at line 22 of file MomentumFreeSlipBC.h.

Constructor & Destructor Documentation

MomentumFreeSlipBC()

MomentumFreeSlipBC::MomentumFreeSlipBC

(

const InputParameters &

parameters

)

Definition at line 31 of file MomentumFreeSlipBC.C.

  : NodalNormalBC(parameters),
    _mesh_dimension(_mesh.dimension()),
    _rho_u(coupledValue("rho_u")),
    _rho_v(_mesh_dimension >= 2 ? coupledValue("rho_v") : _zero),
    _rho_w(_mesh_dimension >= 3 ? coupledValue("rho_w") : _zero)
{
}

~MomentumFreeSlipBC()

MomentumFreeSlipBC::~MomentumFreeSlipBC ( )

virtual

Definition at line 40 of file MomentumFreeSlipBC.C.

{}

Member Function Documentation

computeQpResidual()

Real MomentumFreeSlipBC::computeQpResidual ( )

overrideprotectedvirtual

Definition at line 50 of file MomentumFreeSlipBC.C.

{
  for (auto tag : _vector_tags)
    if (_sys.hasVector(tag) && _var.isNodalDefined())
    {
      auto & residual = _sys.getVector(tag);
 
      if (_mesh_dimension == 1)
      {
        mooseError(name(), ": Not implemented yet");
      }
      else if (_mesh_dimension == 2)
      {
        MooseVariable & rho_u_var = *getVar("rho_u", 0);
        auto && rho_u_dof_idx = rho_u_var.nodalDofIndex();
 
        MooseVariable & rho_v_var = *getVar("rho_v", 0);
        auto && rho_v_dof_idx = rho_v_var.nodalDofIndex();
 
        Real rho_un = _normal(0) * _rho_u[0] + _normal(1) * _rho_v[0];
        Real Re_u = residual(rho_u_dof_idx);
        Real Re_v = residual(rho_v_dof_idx);
 
        // We obtain these contributions in 3 steps:
        // 1.) Tranform the momentum residuals into (tangential, normal)
        //     components by left-multiplying the residual by:
        //     R = [tx ty] = [-ny nx]
        //         [nx ny]   [ nx ny]
        // 2.) Impose the no-normal-flow BC, rho_un = 0, in the normal momentum component's
        // residual.
        // 3.) Transform back to (x,y) momentum components by left-multiplying the residual by
        // R^{-1} = R^T.
        Real rho_u_val =
            (Re_u * _normal(1) * _normal(1) - Re_v * _normal(0) * _normal(1)) + rho_un * _normal(0);
        Real rho_v_val = (-Re_u * _normal(0) * _normal(1) + Re_v * _normal(0) * _normal(0)) +
                         rho_un * _normal(1);
 
        // NOTE: we have to handle all components at the same time, otherwise we'd work with the
        // modified residual and we do not want that
        residual.set(rho_u_dof_idx, rho_u_val);
        residual.set(rho_v_dof_idx, rho_v_val);
      }
      else if (_mesh_dimension == 3)
      {
        mooseError(name(), ": Not implemented yet");
      }
    }
 
  // The return value is not used for anything, so we simply return 0.
  return 0.;
}

shouldApply()

bool MomentumFreeSlipBC::shouldApply ( )

overridevirtual

Definition at line 43 of file MomentumFreeSlipBC.C.

{
  // this prevents zeroing out the row
  return !_fe_problem.currentlyComputingJacobian();
}

Member Data Documentation

_mesh_dimension

const unsigned int MomentumFreeSlipBC::_mesh_dimension

protected

The dimension of the mesh.

Definition at line 34 of file MomentumFreeSlipBC.h.

Referenced by computeQpResidual().

_rho_u

const VariableValue& MomentumFreeSlipBC::_rho_u

protected

Momentum in x-direction.

Definition at line 37 of file MomentumFreeSlipBC.h.

Referenced by computeQpResidual().

_rho_v

const VariableValue& MomentumFreeSlipBC::_rho_v

protected

Momentum in y-direction.

Definition at line 39 of file MomentumFreeSlipBC.h.

Referenced by computeQpResidual().

_rho_w

const VariableValue& MomentumFreeSlipBC::_rho_w

protected

Momentum in z-direction.

Definition at line 41 of file MomentumFreeSlipBC.h.

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The documentation for this class was generated from the following files:

• navier_stokes/include/bcs/MomentumFreeSlipBC.h
• navier_stokes/src/bcs/MomentumFreeSlipBC.C