mesh_from_triangle_navier_stokes.cc

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//LIC// Copyright (C) 2006-2025 Matthias Heil and Andrew Hazel
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//LIC//====================================================================
//Driver for flow past rectangular box -- meshed with triangle
 
//Generic includes
#include "generic.h"
#include "navier_stokes.h"
 
// The mesh
#include "meshes/triangle_mesh.h"
 
using namespace std;
 
using namespace oomph; 
 
//==start_of_namespace==============================
/// Namespace for physical parameters
//==================================================
namespace Global_Physical_Variables
{
 
 /// Reynolds number
 double Re=10.0; 
 
} // end_of_namespace
 
 
 
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
 
 
 
//==start_of_problem_class============================================
/// Flow past a box in a channel
//====================================================================
template<class ELEMENT>
class FlowPastBoxProblem : public Problem
{
 
public:
 
 
 /// Constructor: Pass filenames for mesh
 FlowPastBoxProblem(const string& node_file_name,
                    const string& element_file_name,
                    const string& poly_file_name);
 
 /// Destructor (empty)
 ~FlowPastBoxProblem(){}
 
 /// Update the after solve (empty)
 void actions_after_newton_solve(){}
 
 /// Update the problem specs before solve. 
 /// Re-set velocity boundary conditions just to be on the safe side...
 void actions_before_newton_solve()
 {
  // Find max. and min y-coordinate at inflow
  double y_min=1.0e20;
  double y_max=-1.0e20;
  unsigned ibound=0;
  unsigned num_nod= mesh_pt()->nboundary_node(ibound);
  for (unsigned inod=0;inod<num_nod;inod++)
   {
    double y=mesh_pt()->boundary_node_pt(ibound,inod)->x(1);
    if (y>y_max)
     {
      y_max=y;
     }
    if (y<y_min)
     {
      y_min=y;
     }
   }
 
  // Loop over all boundaries
  for (unsigned ibound=0;ibound<mesh_pt()->nboundary();ibound++)
   {
    unsigned num_nod= mesh_pt()->nboundary_node(ibound);
    for (unsigned inod=0;inod<num_nod;inod++)
     {
      // Parabolic horizontal flow at inflow
      if (ibound==0)
       {
        double y=mesh_pt()->boundary_node_pt(ibound,inod)->x(1);
        double veloc=(y-y_min)*(y_max-y);
        mesh_pt()->boundary_node_pt(ibound,inod)->set_value(0,veloc);
       }
      // Zero horizontal flow elsewhere (either as IC or otherwise)
      else
       {
        mesh_pt()->boundary_node_pt(ibound,inod)->set_value(0,0.0);
       }
      // Zero vertical flow on all boundaries
      mesh_pt()->boundary_node_pt(ibound,inod)->set_value(1,0.0);
     }
   }
 } // end_of_actions_before_newton_solve
 
#ifdef ADAPT
 // Perform actions after mesh adaptation
 void actions_after_adapt();
#endif
 
#ifdef ADAPT
 /// Access function for the specific mesh
 RefineableTriangleMesh<ELEMENT>* mesh_pt() 
  {
   return dynamic_cast<RefineableTriangleMesh<ELEMENT>*>(Problem::mesh_pt());
  }
#else
 /// Access function for the specific mesh
 TriangleMesh<ELEMENT>* mesh_pt() 
  {
   return dynamic_cast<TriangleMesh<ELEMENT>*>(Problem::mesh_pt());
  }
#endif
 
 /// Doc the solution
 void doc_solution(DocInfo& doc_info);
 
#ifdef ADAPT
private:
 /// Pointer to the bulk mesh
 RefineableTriangleMesh<ELEMENT> *Bulk_mesh_pt;
 
 /// Error estimator
 Z2ErrorEstimator* error_estimator_pt;
 
#endif
 
}; // end_of_problem_class
 
 
//==start_of_constructor==================================================
/// Constructor for FlowPastBox problem. Pass filenames for mesh
//========================================================================
template<class ELEMENT>
FlowPastBoxProblem<ELEMENT>::FlowPastBoxProblem(
 const string& node_file_name,
 const string& element_file_name,
 const string& poly_file_name)
{ 
 
 Problem::Max_residuals=1000.0;
 
#ifdef ADAPT
 //Create mesh
 Bulk_mesh_pt = new RefineableTriangleMesh<ELEMENT>(node_file_name,
                                                    element_file_name,
                                                    poly_file_name);
 
 // Set error estimator for bulk mesh
 Z2ErrorEstimator* error_estimator_pt=new Z2ErrorEstimator;
 Bulk_mesh_pt->spatial_error_estimator_pt() = error_estimator_pt;
 
 // Set the problem mesh pointer to the bulk mesh
 Problem::mesh_pt() = Bulk_mesh_pt;
 
#else
 //Create mesh
 Problem::mesh_pt() = new TriangleMesh<ELEMENT>(node_file_name,
                                                element_file_name,
                                                poly_file_name);
#endif
 
 // Set the boundary conditions for this problem: All nodes are
 // free by default -- just pin the ones that have Dirichlet conditions
 // here. 
 unsigned num_bound = mesh_pt()->nboundary();
 for(unsigned ibound=0;ibound<num_bound;ibound++)
  {
   unsigned num_nod= mesh_pt()->nboundary_node(ibound);
   for (unsigned inod=0;inod<num_nod;inod++)
    {
     // Pin horizontal velocity everywhere apart from pure outflow
     if ((ibound!=2))
      {       
       mesh_pt()->boundary_node_pt(ibound,inod)->pin(0); 
      }
 
     // Pin vertical velocity everywhere
     mesh_pt()->boundary_node_pt(ibound,inod)->pin(1); 
    }
  } // end loop over boundaries
 
 // Complete the build of all elements so they are fully functional
 
 //Find number of elements in mesh
 unsigned n_element = mesh_pt()->nelement();
 
 // Loop over the elements to set up element-specific 
 // things that cannot be handled by constructor
 for(unsigned e=0;e<n_element;e++)
  {
   // Upcast from GeneralisedElement to the present element
   ELEMENT* el_pt = dynamic_cast<ELEMENT*>(mesh_pt()->element_pt(e));
 
   //Set the Reynolds number
   el_pt->re_pt() = &Global_Physical_Variables::Re;
  } // end loop over elements
 
 
 // Setup equation numbering scheme
 cout <<"Number of equations: " << assign_eqn_numbers() << std::endl; 
 
} // end_of_constructor
 
#ifdef ADAPT
//========================================================================
// Perform actions after mesh adaptation
//========================================================================
template<class ELEMENT>
void FlowPastBoxProblem<ELEMENT>::actions_after_adapt()
{
 
 // Pin the nodes and make all the element fully functional since the
 // mesh adaptation generated a new mesh
 
 // Set the boundary conditions for this problem: All nodes are
 // free by default -- just pin the ones that have Dirichlet conditions
 // here. 
 unsigned num_bound = mesh_pt()->nboundary();
 for(unsigned ibound=0;ibound<num_bound;ibound++)
  {
   unsigned num_nod= mesh_pt()->nboundary_node(ibound);
   for (unsigned inod=0;inod<num_nod;inod++)
    {
     // Pin horizontal velocity everywhere apart from pure outflow
     if ((ibound!=2))
      {       
       mesh_pt()->boundary_node_pt(ibound,inod)->pin(0); 
      }
 
     // Pin vertical velocity everywhere
     mesh_pt()->boundary_node_pt(ibound,inod)->pin(1); 
    }
  } // end loop over boundaries
 
 // Complete the build of all elements so they are fully functional
 
 //Find number of elements in mesh
 unsigned n_element = mesh_pt()->nelement();
 
 // Loop over the elements to set up element-specific 
 // things that cannot be handled by constructor
 for(unsigned e=0;e<n_element;e++)
  {
   // Upcast from GeneralisedElement to the present element
   ELEMENT* el_pt = dynamic_cast<ELEMENT*>(mesh_pt()->element_pt(e));
 
   //Set the Reynolds number
   el_pt->re_pt() = &Global_Physical_Variables::Re;
  } // end loop over elements
 
 
 // Setup equation numbering scheme
 cout <<"Number of equations: " << assign_eqn_numbers() << std::endl; 
 
}
#endif
 
 
//==start_of_doc_solution=================================================
/// Doc the solution
//========================================================================
template<class ELEMENT>
void FlowPastBoxProblem<ELEMENT>::doc_solution(DocInfo& doc_info)
{ 
 ofstream some_file;
 char filename[100];
 
 // Number of plot points
 unsigned npts;
 npts=5; 
 
 // Output solution 
 snprintf(filename, sizeof(filename), "%s/soln%i.dat",doc_info.directory().c_str(),
         doc_info.number());
 some_file.open(filename);
 mesh_pt()->output(some_file,npts);
 some_file.close();
 
 // Get norm of solution
 snprintf(filename, sizeof(filename), "%s/norm%i.dat",doc_info.directory().c_str(),
         doc_info.number());
 some_file.open(filename);
 double norm_soln=0.0;
 mesh_pt()->compute_norm(norm_soln);  
 some_file << sqrt(norm_soln) << std::endl;
 cout << "Norm of computed solution: "   << sqrt(norm_soln)  << endl;
 some_file.close();
 
 
} // end_of_doc_solution
 
 
 
 
 
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
 
 
 
 
 
 
 
//==start_of_main======================================================
/// Driver for FlowPastBox test problem
//=====================================================================
int main(int argc, char* argv[])
{
 
// Store command line arguments
 CommandLineArgs::setup(argc,argv);
 
 
 // Check number of command line arguments: Need exactly two.
 if (argc!=4)
  {
   std::string error_message =
    "Wrong number of command line arguments.\n";
   error_message +=
    "Must specify the following file names  \n";
   error_message += 
    "filename.node then filename.ele then filename.poly\n";
   
   throw OomphLibError(error_message,
                       OOMPH_CURRENT_FUNCTION,
                       OOMPH_EXCEPTION_LOCATION);
  }
 
 
 // Convert arguments to strings that specify the input file names
 string node_file_name(argv[1]);
 string element_file_name(argv[2]);
 string poly_file_name(argv[3]);
 
 
 // Set up doc info
 // ---------------
 
 // Label for output
 DocInfo doc_info;
 
 // Set output directory
 doc_info.set_directory("RESLT");
 
 // Step number
 doc_info.number()=0;
 
#ifdef ADAPT
 const unsigned max_adapt = 3;
#endif
 
// Doing TTaylorHoodElements
 {
#ifdef ADAPT
  // Build the problem with TTaylorHoodElements
  FlowPastBoxProblem<ProjectableTaylorHoodElement<TTaylorHoodElement<2> > >
   problem(node_file_name, element_file_name, poly_file_name);
#else
  // Build the problem with TTaylorHoodElements
  FlowPastBoxProblem<TTaylorHoodElement<2> > 
   problem(node_file_name, element_file_name, poly_file_name);
#endif
  // Output boundaries 
  problem.mesh_pt()->output_boundaries("RESLT/boundaries.dat");
 
  // Outpt the solution
  problem.doc_solution(doc_info);
  
  // Step number
  doc_info.number()++;
  
#ifdef ADAPT
  // Solve the problem
  problem.newton_solve(max_adapt);
#else
  // Solve the problem
  problem.newton_solve();
#endif
  
  // Outpt the solution
  problem.doc_solution(doc_info);
  
  // Step number
  doc_info.number()++;
  
 } // end of QTaylorHoodElements
 
 
} // end_of_main