HYPAcousticImpedance.cpp File Reference

Solve the constant coefficient linear sound wave problem. More...

#include <OneD_HYP_bundle.h>

Go to the source code of this file.

Classes
class	CppNoddy::Example::Acoustic_1d
	Define the system. More...

Namespaces
namespace	CppNoddy
	A collection of OO numerical routines aimed at simple (typical) applied problems in continuum mechanics.
namespace	CppNoddy::Example

Enumerations
enum	{ p , u }

Functions
double	CppNoddy::Example::K (4.0)
	bulk modulus More...
double	CppNoddy::Example::rho_big (4.0)
	higher density More...
double	CppNoddy::Example::rho_small (1.0)
	lower density More...
double	CppNoddy::Example::rho (const double &x)
	Density function for the medium. More...
void	CppNoddy::Example::Q_init (const double &x, DenseVector< double > &q)
	Set the initial state of the system. More...
int	main ()

Detailed Description

Solve the constant coefficient linear sound wave problem.

for a right-propagating square pressure pulse in a medium with constant bulk modulus and density if and elsewhere. The (first) reflected wave's velocity amplitude is

where and are the bulk modulus and wave speed before and after the density interface, with .

Definition in file HYPAcousticImpedance.cpp.

Enumeration Type Documentation

anonymous enum

anonymous enum

Enumerator
p
u

Definition at line 17 of file HYPAcousticImpedance.cpp.

{ p, u };

Function Documentation

main()

int main

(

)

Definition at line 91 of file HYPAcousticImpedance.cpp.

{
  cout << "\n";
  cout << "=== Hyperbolic: 1D acoustic wave, impedance problem =\n";
  cout << "\n";
 
  // define the domain/mesh
  const double left =  -7.0;
  const double right = 7.0;
  const unsigned N = 800;
  DenseVector<double> faces_x = Utility::uniform_node_vector( left, right, N );
 
  // time
  double t = 0.0;
  double t_end = 5.0;
 
  // hyperbolic problem
  Example::Acoustic_1d conservative_problem;
  OneD_TVDLF_Mesh Acoustic_mesh( faces_x, &conservative_problem, Example::Q_init );
  Acoustic_mesh.set_limiter( 1 );
 
  // mesh & test info
  double I1 = Acoustic_mesh.integrate()[0];
  int loop_counter( 4 );
  int file_counter( 1 );
 
  std::string dirname("./DATA");
  mkdir( dirname.c_str(), S_IRWXU );
  std::string filename_stub;
  filename_stub = "./DATA/HYP_acoustic_imp";
  TrackerFile my_file( 5 );
  OneD_Node_Mesh<double> soln = Acoustic_mesh.get_soln();
  my_file.push_ptr( &soln, "mesh" );
 
  do
  {
    t += Acoustic_mesh.update( 0.499, t_end - t );
 
    if ( loop_counter % 2 == 0 )
    {
      my_file.set_filename( filename_stub + Utility::stringify( file_counter ) + ".dat" );
      soln = Acoustic_mesh.get_soln();
      my_file.update();
      file_counter += 1;
    }
    ++loop_counter;
 
  }
  while ( ( t < t_end ) && ( loop_counter < 1500 ) );
 
  soln = Acoustic_mesh.get_soln();
  double I2 = Acoustic_mesh.integrate()[0];
  // the first reflected and first transmitted pulses can be determined explicitly.
  // they have amplitude ratios of 1/3 and 8/9ths of the input amplitude for the pressure.
  soln = Acoustic_mesh.get_soln();
  double E1 = std::abs( soln.get_interpolated_vars( -5.0 )[0] - 1. / 3. );
  double E2 = std::abs( soln.get_interpolated_vars(  4.0 )[0] - 8. / 9. );
  if ( ( E1 > 1.e-4 ) || ( E2 > 1.e-4 ) || ( std::abs( I1 - I2 ) > 1.e-8 ) || ( loop_counter >= 1500 ) )
  {
    cout << "\033[1;31;48m  * FAILED \033[0m\n";
    return 1;
  }
  else
  {
    cout << "\033[1;32;48m  * PASSED \033[0m\n";
    return 0;
  }
 
} // end of main()

References CppNoddy::OneD_Node_Mesh< _Type, _Xtype >::get_interpolated_vars(), CppNoddy::OneD_TVDLF_Mesh::get_soln(), CppNoddy::OneD_TVDLF_Mesh::integrate(), CppNoddy::TrackerFile::push_ptr(), CppNoddy::TrackerFile::set_filename(), CppNoddy::OneD_TVDLF_Mesh::set_limiter(), CppNoddy::Utility::stringify(), CppNoddy::Utility::uniform_node_vector(), CppNoddy::TrackerFile::update(), and CppNoddy::OneD_TVDLF_Mesh::update().