two_d_poisson_flux_bc.cc File Reference

#include "generic.h"
#include "poisson.h"
#include "meshes/simple_rectangular_quadmesh.h"

Classes
class	FluxPoissonProblem< ELEMENT >

Namespaces
	TanhSolnForPoisson
	Namespace for exact solution for Poisson equation with "sharp step".

Functions
void	TanhSolnForPoisson::get_exact_u (const Vector< double > &x, Vector< double > &u)
	Exact solution as a Vector. More...
void	TanhSolnForPoisson::source_function (const Vector< double > &x, double &source)
	Source function required to make the solution above an exact solution. More...
void	TanhSolnForPoisson::prescribed_flux_on_fixed_x_boundary (const Vector< double > &x, double &flux)
	Flux required by the exact solution on a boundary on which x is fixed. More...
int	main ()

Function Documentation

main()

int main

(

)

Demonstrate how to solve 2D Poisson problem with flux boundary conditions

{
 
 //Set up the problem
 //------------------
 
 //Set up the problem with 2D nine-node elements from the
 //QPoissonElement family. Pass pointer to source function. 
 FluxPoissonProblem<QPoissonElement<2,3> > 
  problem(&TanhSolnForPoisson::source_function);
 
 
 // Create label for output
 //------------------------
 DocInfo doc_info;
 
 // Set output directory
 doc_info.set_directory("RESLT");
 
 // Step number
 doc_info.number()=0;
 
 
 
 // Check that we're ready to go:
 //----------------------------
 cout << "\n\n\nProblem self-test ";
 if (problem.self_test()==0) 
  {
   cout << "passed: Problem can be solved." << std::endl;
  }
 else 
  {
   throw OomphLibError("Self test failed",
                       OOMPH_CURRENT_FUNCTION,
                       OOMPH_EXCEPTION_LOCATION);
  }
 
 
 // Set the orientation of the "step" to 45 degrees
 TanhSolnForPoisson::TanPhi=1.0;
 
 // Initial value for the steepness of the "step"
 TanhSolnForPoisson::Alpha=1.0; 
 
 // Do a couple of solutions for different forcing functions
 //---------------------------------------------------------
 unsigned nstep=4;
 for (unsigned istep=0;istep<nstep;istep++)
  {
   // Increase the steepness of the step:
   TanhSolnForPoisson::Alpha+=2.0;
 
   cout << "\n\nSolving for TanhSolnForPoisson::Alpha="
        << TanhSolnForPoisson::Alpha << std::endl << std::endl;
 
   // Solve the problem
   problem.newton_solve();
 
   //Output solution
   problem.doc_solution(doc_info);
 
   //Increment counter for solutions 
   doc_info.number()++; 
  }
 
} //end of main

References TanhSolnForPoisson::Alpha, oomph::DocInfo::number(), OOMPH_CURRENT_FUNCTION, OOMPH_EXCEPTION_LOCATION, problem, oomph::DocInfo::set_directory(), TanhSolnForPoisson::source_function(), and TanhSolnForPoisson::TanPhi.