GRINS::PressurePinning Class Reference

Class to hold typical boundary condition methods. More...

#include <pressure_pinning.h>

Public Member Functions
	PressurePinning (const GetPot &input, const std::string &physics_name)
	~PressurePinning ()
void	pin_value (libMesh::DiffContext &context, const bool request_jacobian, const GRINS::VariableIndex var, const double penalty=1.0)
	The idea here is to pin a variable to a particular value if there is a null space - e.g. More...

Private Attributes
libMesh::Number	_pin_value
	Value of pressure we wish to pin. More...
libMesh::Point	_pin_location
	Location we want to pin the pressure. More...

Detailed Description

Class to hold typical boundary condition methods.

This class holds functions to apply generic versions of Dirichlet and Neumann boundary conditions.

Definition at line 51 of file pressure_pinning.h.

Constructor & Destructor Documentation

GRINS::PressurePinning::PressurePinning	(	const GetPot &	input,
		const std::string &	physics_name
	)

Definition at line 40 of file pressure_pinning.C.

References _pin_location, and _pin_value.

  {
    _pin_value = input("Physics/"+physics_name+"/pin_value", 0.0 );

    unsigned int pin_loc_dim = input.vector_variable_size("Physics/"+physics_name+"/pin_location");

    // If the user is specifying a pin_location, it had better be at least 2-dimensional
    if( pin_loc_dim > 0 && pin_loc_dim < 2 )
      {
        std::cerr << "Error: pressure pin location must be at least 2 dimensional"
                  << std::endl;
        libmesh_error();
      }

    _pin_location(0) = input("Physics/"+physics_name+"/pin_location", 0.0, 0 );
    _pin_location(1) = input("Physics/"+physics_name+"/pin_location", 0.0, 1 );

    if( pin_loc_dim == 3 ) 
      _pin_location(2) = input("Physics/"+physics_name+"/pin_location", 0.0, 2 );

    return;
  }

GRINS::PressurePinning::~PressurePinning

(

)

Definition at line 64 of file pressure_pinning.C.

  {
    return;
  }

Member Function Documentation

void GRINS::PressurePinning::pin_value	(	libMesh::DiffContext &	context,
		const bool	request_jacobian,
		const GRINS::VariableIndex	var,
		const double	penalty = 1.0
	)

The idea here is to pin a variable to a particular value if there is a null space - e.g.

pressure for IncompressibleNavierStokes.

Todo:

pin_location needs to be const. Currently a libMesh restriction.

Todo:

What the hell is the c.get_elem_solution_derivative() all about?

Definition at line 69 of file pressure_pinning.C.

References _pin_location, and _pin_value.

  {
    AssemblyContext &c = libMesh::libmesh_cast_ref<AssemblyContext&>(context);

    if (c.get_elem().contains_point(_pin_location))
      {
        libMesh::DenseSubVector<libMesh::Number> &F_var = c.get_elem_residual(var); // residual
        libMesh::DenseSubMatrix<libMesh::Number> &K_var = c.get_elem_jacobian(var, var); // jacobian

        // The number of local degrees of freedom in p variable.
        const unsigned int n_var_dofs = c.get_dof_indices(var).size();

        libMesh::Number var_value = c.point_value(var, _pin_location);

        libMesh::FEType fe_type = c.get_element_fe(var)->get_fe_type();
      
        libMesh::Point point_loc_in_masterelem = 
          libMesh::FEInterface::inverse_map(c.get_dim(), fe_type, &c.get_elem(), _pin_location);

        std::vector<libMesh::Real> phi(n_var_dofs);

        for (unsigned int i=0; i != n_var_dofs; i++)
          phi[i] = libMesh::FEInterface::shape( c.get_dim(), fe_type, &c.get_elem(), i, 
                                                point_loc_in_masterelem );
      
        for (unsigned int i=0; i != n_var_dofs; i++)
          {
            F_var(i) += penalty*(var_value - _pin_value)*phi[i];
          
            if (request_jacobian && c.get_elem_solution_derivative())
              {
                libmesh_assert (c.get_elem_solution_derivative() == 1.0);
              
                for (unsigned int j=0; j != n_var_dofs; j++)
                  K_var(i,j) += penalty*phi[i]*phi[j];

              } // End if request_jacobian
          } // End i loop
      } // End if pin_location

    return;
  }

Member Data Documentation

libMesh::Point GRINS::PressurePinning::_pin_location

private

Location we want to pin the pressure.

Definition at line 72 of file pressure_pinning.h.

Referenced by pin_value(), and PressurePinning().

libMesh::Number GRINS::PressurePinning::_pin_value

private

Value of pressure we wish to pin.

Definition at line 69 of file pressure_pinning.h.

Referenced by pin_value(), and PressurePinning().

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

• src/boundary_conditions/include/grins/pressure_pinning.h
• src/boundary_conditions/src/pressure_pinning.C