algebraic_free_boundary_poisson.cc

Go to the documentation of this file.

//LIC// ====================================================================
//LIC// This file forms part of oomph-lib, the object-oriented, 
//LIC// multi-physics finite-element library, available 
//LIC// at http://www.oomph-lib.org.
//LIC// 
//LIC// Copyright (C) 2006-2023 Matthias Heil and Andrew Hazel
//LIC// 
//LIC// This library is free software; you can redistribute it and/or
//LIC// modify it under the terms of the GNU Lesser General Public
//LIC// License as published by the Free Software Foundation; either
//LIC// version 2.1 of the License, or (at your option) any later version.
//LIC// 
//LIC// This library is distributed in the hope that it will be useful,
//LIC// but WITHOUT ANY WARRANTY; without even the implied warranty of
//LIC// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//LIC// Lesser General Public License for more details.
//LIC// 
//LIC// You should have received a copy of the GNU Lesser General Public
//LIC// License along with this library; if not, write to the Free Software
//LIC// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
//LIC// 02110-1301  USA.
//LIC// 
//LIC// The authors may be contacted at oomph-lib@maths.man.ac.uk.
//LIC// 
//LIC//====================================================================
// Driver for solution of "free boundary" 2D Poisson equation in 
// fish-shaped domain with adaptivity
 
 
// Generic oomph-lib headers
#include "generic.h"
 
// The Poisson equations
#include "poisson.h"
 
// The fish mesh 
#include "meshes/fish_mesh.h"
 
// Circle as generalised element:
#include "circle_as_generalised_element.h"
 
using namespace std;
 
using namespace oomph;
 
/// ////////////////////////////////////////////////////////////////////
/// ////////////////////////////////////////////////////////////////////
/// ////////////////////////////////////////////////////////////////////
 
 
 
//====================================================================
/// Namespace for const source term in Poisson equation
//====================================================================
namespace ConstSourceForPoisson
{
 /// Strength of source function: default value 1.0
 double Strength=1.0;
 
/// Const source function
 void get_source(const Vector<double>& x, double& source)
 {
  source = -Strength*(1.0+x[0]*x[1]);
 }
 
}
 
 
/// /////////////////////////////////////////////////////////////////////
/// /////////////////////////////////////////////////////////////////////
/// /////////////////////////////////////////////////////////////////////
 
 
 
//====================================================================
/// Refineable Poisson problem in deformable fish-shaped domain.
/// Template parameter identify the elements.
//====================================================================
template<class ELEMENT>
class RefineableFishPoissonProblem : public Problem
{
 
public:
 
 ///  Constructor: Bool flag specifies if position of fish back is
 /// prescribed or computed from the coupled problem. String specifies
 /// output directory.
 RefineableFishPoissonProblem(
  const bool& fix_position, const string& directory_name,
  const unsigned& i_case);
  
 /// Destructor
 virtual ~RefineableFishPoissonProblem();
 
 /// Update after Newton step: Update mesh in response to 
 /// possible changes in the wall shape
 void actions_before_newton_convergence_check()
  {
   fish_mesh_pt()->node_update();
  }
 
 /// Update the problem specs after solve (empty)
 void actions_after_newton_solve(){}
  
 /// Update the problem specs before solve: Update mesh
 void actions_before_newton_solve() 
  {
   fish_mesh_pt()->node_update();
  }
 
 //Access function for the fish mesh
 AlgebraicRefineableFishMesh<ELEMENT>* fish_mesh_pt() 
  {
   return Fish_mesh_pt;
  }
 
 /// Return value of the "load" on the elastically supported ring
 double& load()
  {
   return *Load_pt->value_pt(0);
  }
 
 
 /// Return value of the vertical displacement of the ring that
 /// represents the fish's back
 double& y_c()
  {
   return static_cast<ElasticallySupportedRingElement*>(fish_mesh_pt()->
                                                        fish_back_pt())->y_c();
  }
 
 /// Doc the solution
 void doc_solution();
 
 /// Access to DocInfo object
 DocInfo& doc_info() {return Doc_info;}
 
private:
 
 /// Helper fct to set method for evaluation of shape derivs
 void set_shape_deriv_method()
  {
   
   bool done=false;
 
   //Loop over elements and set pointers to source function
   unsigned n_element = fish_mesh_pt()->nelement();
   for(unsigned i=0;i<n_element;i++)
    {
     // Upcast from FiniteElement to the present element
     ELEMENT *el_pt = dynamic_cast<ELEMENT*>(fish_mesh_pt()->element_pt(i));
     
     // Direct FD
     if (Case_id==0)
      {
       el_pt->evaluate_shape_derivs_by_direct_fd();       
       if (!done) std::cout << "\n\n [CR residuals] Direct FD" << std::endl;
      }
     // Chain rule with/without FD
     else if ( (Case_id==1) ||  (Case_id==2) )
      {
       // It's broken but let's call it anyway to keep self-test alive
       bool i_know_what_i_am_doing=true;
       el_pt->evaluate_shape_derivs_by_chain_rule(i_know_what_i_am_doing);
       if (Case_id==1)
        {
         el_pt->enable_always_evaluate_dresidual_dnodal_coordinates_by_fd();
         if (!done) std::cout << "\n\n [CR residuals] Chain rule and FD" 
                              << std::endl;
        }
       else
        {
         el_pt->disable_always_evaluate_dresidual_dnodal_coordinates_by_fd();
         if (!done) std::cout << "\n\n [CR residuals] Chain rule and analytic" 
                              << std::endl;
        }
      }
     // Fastest with/without FD
     else if ( (Case_id==3) ||  (Case_id==4) )
      {
       // It's broken but let's call it anyway to keep self-test alive
       bool i_know_what_i_am_doing=true;
       el_pt->evaluate_shape_derivs_by_fastest_method(i_know_what_i_am_doing);
       if (Case_id==3)
        {
         el_pt->enable_always_evaluate_dresidual_dnodal_coordinates_by_fd();
         if (!done) std::cout << "\n\n [CR residuals] Fastest and FD" 
                              << std::endl;
        }
       else
        {
         el_pt->disable_always_evaluate_dresidual_dnodal_coordinates_by_fd();
         if (!done) std::cout << "\n\n [CR residuals] Fastest and analytic" 
                              << std::endl;
         
        }
      }
     done=true;
    }
   
  }
 
 /// Node at which the solution of the Poisson equation is documented
 Node* Doc_node_pt;
 
 /// Trace file
 ofstream Trace_file;
 
 /// Pointer to fish mesh
 AlgebraicRefineableFishMesh<ELEMENT>* Fish_mesh_pt;
 
 /// Pointer to single-element mesh that stores the GeneralisedElement
 /// that represents the fish back
 Mesh* Fish_back_mesh_pt;
 
 /// Pointer to data item that stores the "load" on the fish back
 Data* Load_pt;
 
 /// Is the position of the fish back prescribed?
 bool Fix_position;
 
 /// Doc info object
 DocInfo Doc_info;
 
 /// Case id
 unsigned Case_id;
 
};
 
 
 
 
 
//========================================================================
/// Constructor for adaptive Poisson problem in deformable fish-shaped
/// domain. Pass flag if position of fish back is fixed, and the output
/// directory. 
//========================================================================
template<class ELEMENT>
RefineableFishPoissonProblem<ELEMENT>::RefineableFishPoissonProblem(
 const bool& fix_position, const string& directory_name,
 const unsigned& i_case) : Fix_position(fix_position), Case_id(i_case)
{ 
 
 
 // Set output directory
 Doc_info.set_directory(directory_name); 
 
 // Initialise step number
 Doc_info.number()=0;
 
 // Open trace file
 char filename[100];
 sprintf(filename,"%s/trace.dat",directory_name.c_str());
 Trace_file.open(filename);
 
 Trace_file 
  << "VARIABLES=\"load\",\"y<sub>circle</sub>\",\"u<sub>control</sub>\""
  << std::endl;
 
 // Set coordinates and radius for the circle that will become the fish back
 double x_c=0.5;
 double y_c=0.0;
 double r_back=1.0;
 
 // Build geometric element that will become the fish back
 GeomObject* fish_back_pt=new ElasticallySupportedRingElement(x_c,y_c,r_back);
 
 // Build fish mesh with geometric object that specifies the fish back 
 Fish_mesh_pt=new AlgebraicRefineableFishMesh<ELEMENT>(fish_back_pt);
 
 // Add the fish mesh to the problem's collection of submeshes:
 add_sub_mesh(Fish_mesh_pt);
 
 // Build mesh that will store only the geometric wall element
 Fish_back_mesh_pt=new Mesh;
 
 // So far, the mesh is completely empty. Let's add the 
 // one (and only!) GeneralisedElement which represents the shape
 // of the fish's back to it:
 Fish_back_mesh_pt->add_element_pt(dynamic_cast<GeneralisedElement*>(
                                    Fish_mesh_pt->fish_back_pt()));
 
 // Add the fish back mesh to the problem's collection of submeshes:
 add_sub_mesh(Fish_back_mesh_pt);
 
 // Now build global mesh from the submeshes
 build_global_mesh();
 
 
 // Create/set error estimator
 fish_mesh_pt()->spatial_error_estimator_pt()=new Z2ErrorEstimator;
  
 // Choose a node at which the solution is documented: Choose
 // the central node that is shared by all four elements in
 // the base mesh because it exists at all refinement levels.
 
 // How many nodes does element 0 have?
 unsigned nnod=fish_mesh_pt()->finite_element_pt(0)->nnode();
 
 // The central node is the last node in element 0:
 Doc_node_pt=fish_mesh_pt()->finite_element_pt(0)->node_pt(nnod-1);
 
 // Doc
 cout << std::endl <<  "Control node is located at: " 
      << Doc_node_pt->x(0) << " " << Doc_node_pt->x(1) 
      << std::endl << std::endl;
 
 // Position of fish back is prescribed
 if (Fix_position)
  {
   // Create the load data object
   Load_pt=new Data(1);
   
   // Pin the prescribed load
   Load_pt->pin(0);
 
   // Pin the vertical displacement
   dynamic_cast<ElasticallySupportedRingElement*>(
    Fish_mesh_pt->fish_back_pt())->pin_yc();
  }
 // Coupled problem: The position of the fish back is determined
 // via the solution of the Poisson equation: The solution at
 // the control node acts as the load for the displacement of the
 // fish back
 else
  {   
   // Use the solution (value 0) at the control node as the load
   // that acts on the ring. [Note: Node == Data by inheritance]
   Load_pt=Doc_node_pt;
  }
 
 
 // Set the pointer to the Data object that specifies the 
 // load on the fish's back
 dynamic_cast<ElasticallySupportedRingElement*>(Fish_mesh_pt->fish_back_pt())->
  set_load_pt(Load_pt);
 
 
 // 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 = fish_mesh_pt()->nboundary();
 for(unsigned ibound=0;ibound<num_bound;ibound++)
  {
   unsigned num_nod= fish_mesh_pt()->nboundary_node(ibound);
   for (unsigned inod=0;inod<num_nod;inod++)
    {
     fish_mesh_pt()->boundary_node_pt(ibound,inod)->pin(0); 
    }
  }
 
 
 // Set homogeneous boundary conditions on all boundaries 
 for(unsigned ibound=0;ibound<num_bound;ibound++)
  {
   // Loop over the nodes on boundary
   unsigned num_nod=fish_mesh_pt()->nboundary_node(ibound);
   for (unsigned inod=0;inod<num_nod;inod++)
    {
     fish_mesh_pt()->boundary_node_pt(ibound,inod)->set_value(0,0.0);
    }
  }
 
 /// Loop over elements and set pointers to source function
 unsigned n_element = fish_mesh_pt()->nelement();
 for(unsigned i=0;i<n_element;i++)
  {
   // Upcast from FiniteElement to the present element
   ELEMENT *el_pt = dynamic_cast<ELEMENT*>(fish_mesh_pt()->element_pt(i));
   
   //Set the source function pointer
   el_pt->source_fct_pt() = &ConstSourceForPoisson::get_source;
  }
 
 // Set shape derivative method
 set_shape_deriv_method();
 
 // Do equation numbering
 cout <<"Number of equations: " << assign_eqn_numbers() << std::endl; 
 
}
 
 
 
//========================================================================
/// Destructor for Poisson problem in deformable fish-shaped domain.
//========================================================================
template<class ELEMENT>
RefineableFishPoissonProblem<ELEMENT>::~RefineableFishPoissonProblem()
{ 
 // Close trace file
 Trace_file.close();
 
}
 
 
 
 
//========================================================================
/// Doc the solution in tecplot format.
//========================================================================
template<class ELEMENT>
void RefineableFishPoissonProblem<ELEMENT>::doc_solution()
{ 
 
 ofstream some_file;
 char filename[100];
 
 // Number of plot points in each coordinate direction.
 unsigned npts;
 npts=5; 
 
 
 // Output solution 
 if (Case_id!=0)
  {
   sprintf(filename,"%s/soln_%i_%i.dat",Doc_info.directory().c_str(),
           Case_id,Doc_info.number());
  }
 else
  {
   sprintf(filename,"%s/soln%i.dat",Doc_info.directory().c_str(),
           Doc_info.number());
  }
 some_file.open(filename);
 fish_mesh_pt()->output(some_file,npts);
 some_file.close();
 
 // Write "load", vertical position of the fish back, and solution at 
 // control node to trace file
 Trace_file 
  << static_cast<ElasticallySupportedRingElement*>(fish_mesh_pt()->
                                          fish_back_pt())->load()
  << " "
  << static_cast<ElasticallySupportedRingElement*>(fish_mesh_pt()->
                                          fish_back_pt())->y_c()
  << " " << Doc_node_pt->value(0) << std::endl;
}
 
 
 
 
 
 
 
/// /////////////////////////////////////////////////////////////////////
/// /////////////////////////////////////////////////////////////////////
/// /////////////////////////////////////////////////////////////////////
 
 
 
 
 
//========================================================================
/// Demonstrate how to solve 2D Poisson problem in deformable
/// fish-shaped domain with mesh adaptation.
//========================================================================
template<class ELEMENT>
void demo_fish_poisson(const string& directory_name)
{
 
 // Set up the problem with prescribed displacement of fish back
 bool fix_position=true;
 RefineableFishPoissonProblem<ELEMENT> problem(fix_position,directory_name,0);
 
 // Doc refinement targets
 problem.fish_mesh_pt()->doc_adaptivity_targets(cout);
  
 // Do some uniform mesh refinement first
 //--------------------------------------
 problem.refine_uniformly();
 problem.refine_uniformly(); 
 
 // Initial value for the vertical displacement of the fish's back
 problem.y_c()=-0.3;
 
 // Loop for different fish shapes
 //-------------------------------
 
 // Number of steps
 unsigned nstep=5;
 
 // Increment in displacement
 double dyc=0.6/double(nstep-1);
 
 // Valiation: Just do one step
 if (CommandLineArgs::Argc>1) nstep=1;
 
 for (unsigned istep=0;istep<nstep;istep++)
  {    
   // Solve/doc
   unsigned max_solve=2; 
   problem.newton_solve(max_solve);
   problem.doc_solution();
   
   //Increment counter for solutions 
   problem.doc_info().number()++;    
   
   // Change vertical displacement
   problem.y_c()+=dyc;
  } 
}
 
 
//========================================================================
/// Demonstrate how to solve "elastic" 2D Poisson problem in deformable
/// fish-shaped domain with mesh adaptation.
//========================================================================
template<class ELEMENT>
void demo_elastic_fish_poisson(const string& directory_name)
{
 
 // Loop over all cases
 for (unsigned i_case=0;i_case<5;i_case++)
  //unsigned i_case=1;
  {
   std::cout << "[CR residuals] " << std::endl;
   std::cout << "[CR residuals]==================================================" 
             << std::endl;
   std::cout << "[CR residuals] " << std::endl;
   //Set up the problem with "elastic" fish back
   bool fix_position=false;
   RefineableFishPoissonProblem<ELEMENT> problem(fix_position,
                                                 directory_name,
                                                 i_case);
   
   // Doc refinement targets
   problem.fish_mesh_pt()->doc_adaptivity_targets(cout);
   
   // Do some uniform mesh refinement first
   //--------------------------------------
   problem.refine_uniformly();
   problem.refine_uniformly();
   
   
   // Initial value for load on fish back
   problem.load()=0.0;
   
   // Solve/doc
   unsigned max_solve=2; 
   problem.newton_solve(max_solve);
   problem.doc_solution();
  }
 
 
}
 
 
 
 
 
//========================================================================
/// Driver for "elastic" fish poisson solver with adaptation.
/// If there are any command line arguments, we regard this as a 
/// validation run and perform only a single step.
//========================================================================
int main(int argc, char* argv[]) 
{
 // Store command line arguments
 CommandLineArgs::setup(argc,argv);
 
 // Shorthand for element type
  typedef AlgebraicElement<RefineableQPoissonElement<2,3> > ELEMENT;
 
  // Compute solution of Poisson equation in various domains
  demo_fish_poisson<ELEMENT>("RESLT");
 
  // Compute "elastic" coupled solution directly
  demo_elastic_fish_poisson<ELEMENT>("RESLT_coupled"); 
 
}