NSMomentumInviscidFlux.C

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//* This file is part of the MOOSE framework
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//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html
 
// Navier-Stokes includes
#include "NS.h"
#include "NSMomentumInviscidFlux.h"
 
// FluidProperties includes
#include "IdealGasFluidProperties.h"
 
registerMooseObject("NavierStokesApp", NSMomentumInviscidFlux);
 
template <>
InputParameters
validParams<NSMomentumInviscidFlux>()
{
  InputParameters params = validParams<NSKernel>();
  params.addClassDescription(
      "The inviscid flux (convective + pressure terms) for the momentum conservation equations.");
  params.addRequiredCoupledVar(NS::pressure, "pressure");
  params.addRequiredParam<unsigned int>(
      "component",
      "0,1,2 depending on if we are solving the x,y,z component of the momentum equation");
  return params;
}
 
NSMomentumInviscidFlux::NSMomentumInviscidFlux(const InputParameters & parameters)
  : NSKernel(parameters),
    _pressure(coupledValue(NS::pressure)),
    _component(getParam<unsigned int>("component"))
{
}
 
Real
NSMomentumInviscidFlux::computeQpResidual()
{
  // For _component = k,
 
  // (rho*u) * u_k = (rho*u_k) * u <- we write it this way
  RealVectorValue vec(_u[_qp] * _u_vel[_qp],  // (U_k) * u_1
                      _u[_qp] * _v_vel[_qp],  // (U_k) * u_2
                      _u[_qp] * _w_vel[_qp]); // (U_k) * u_3
 
  // (rho*u_k) * u + e_k * P [ e_k = unit vector in k-direction ]
  vec(_component) += _pressure[_qp];
 
  // -((rho*u_k) * u + e_k * P) * grad(phi)
  return -(vec * _grad_test[_i][_qp]);
}
 
Real
NSMomentumInviscidFlux::computeQpJacobian()
{
  // The on-diagonal entry corresponds to variable number _component+1.
  return computeJacobianHelper(_component + 1);
}
 
Real
NSMomentumInviscidFlux::computeQpOffDiagJacobian(unsigned int jvar)
{
  if (isNSVariable(jvar))
    return computeJacobianHelper(mapVarNumber(jvar));
  else
    return 0.0;
}
 
Real
NSMomentumInviscidFlux::computeJacobianHelper(unsigned int m)
{
  const RealVectorValue vel(_u_vel[_qp], _v_vel[_qp], _w_vel[_qp]);
 
  // Ratio of specific heats
  const Real gam = _fp.gamma();
 
  switch (m)
  {
    case 0: // density
    {
      const Real V2 = vel.norm_sq();
      return vel(_component) * (vel * _grad_test[_i][_qp]) -
             0.5 * (gam - 1.0) * V2 * _grad_test[_i][_qp](_component);
    }
 
    case 1:
    case 2:
    case 3: // momentums
    {
      // Map m into m_local = {0,1,2}
      unsigned int m_local = m - 1;
 
      // Kronecker delta
      const Real delta_kl = (_component == m_local ? 1. : 0.);
 
      return -1.0 * (vel(_component) * _grad_test[_i][_qp](m_local) +
                     delta_kl * (vel * _grad_test[_i][_qp]) +
                     (1. - gam) * vel(m_local) * _grad_test[_i][_qp](_component)) *
             _phi[_j][_qp];
    }
 
    case 4: // energy
      return -1.0 * (gam - 1.0) * _phi[_j][_qp] * _grad_test[_i][_qp](_component);
  }
 
  mooseError("Shouldn't get here!");
}