time_harmonic_elastic_annulus.cc

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//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) 2006-2024 Matthias Heil and Andrew Hazel
//LIC// 
//LIC// This library is free software; you can redistribute it and/or
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//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// 
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//LIC// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//LIC// Lesser General Public License for more details.
//LIC// 
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//LIC//====================================================================
// Time-harmonic deformation of an elastic annulus subject to 
//  displacement and pressure
 
//Oomph-lib includes
#include "generic.h"
#include "time_harmonic_linear_elasticity.h"
#include "oomph_crbond_bessel.h"
 
//The meshes
#include "meshes/annular_mesh.h"
 
using namespace std;
using namespace oomph;
 
 
/// ///////////////////////////////////////////////////////////////////
/// ///////////////////////////////////////////////////////////////////
/// ///////////////////////////////////////////////////////////////////
 
 
//=======start_namespace==========================================
/// Global variables
//================================================================
namespace Global_Parameters
{
 
 /// Poisson's ratio
 double Nu = 0.3;
 
 /// Square of non-dim frequency
 double Omega_sq=100.0;
  
 /// The elasticity tensor
 TimeHarmonicIsotropicElasticityTensor E(Nu);
 
 /// Thickness of annulus
 double H_annulus=0.5;
 
 /// Displacement amplitude on inner radius
 double Displacement_amplitude=0.1;
 
 /// Real-valued, radial displacement field on inner boundary
 void solid_boundary_displacement(const Vector<double>& x,
                                  Vector<double>& u)
 {
  Vector<double> normal(2);
  double norm=sqrt(x[0]*x[0]+x[1]*x[1]);
  normal[0]=x[0]/norm;
  normal[1]=x[1]/norm;
 
  u[0]=Displacement_amplitude*normal[0];
  u[1]=Displacement_amplitude*normal[1];
 }
 
 /// Uniform pressure
 double P = 0.0;
 
 /// Constant pressure load (real and imag part)
 void constant_pressure(const Vector<double> &x,
                        const Vector<double> &n, 
                        Vector<std::complex<double> >&traction)
 {
  unsigned dim = traction.size();
  for(unsigned i=0;i<dim;i++)
   {
    traction[i] = complex<double>(-P*n[i],P*n[i]);
   }
 } // end_of_pressure_load
 
 
 /// Output directory
 string Directory="RESLT";
 
 /// Number of elements in azimuthal direction 
 unsigned Ntheta=20;
 
 /// Number of elements in radial direction 
 unsigned Nr=10;
 
 /// Helper function to evaluate Y_n(x) from bloody maple output
 double BesselY(const double& n, const double& x)
 {
  // Bessel fcts J_0(x), J_1(x), Y_0(x), Y_1(x) and their derivatives
  double j0,j1,y0,y1,j0p,j1p,y0p,y1p;
  CRBond_Bessel::bessjy01a(x,j0,j1,y0,y1,j0p,j1p,y0p,y1p);
  
  if (n==0.0)
   {
    return y0;
   }
  else if (n==1.0)
   {
    return y1;
   }
  else
   {
    cout << "Never get here...";
    abort();
   }
   
 }
 
 
 /// Helper function to evaluate J_n(x) from bloody maple output
 double BesselJ(const double& n, const double& x)
 {
  
  // Bessel fcts J_0(x), J_1(x), Y_0(x), Y_1(x) and their derivatives
  double j0,j1,y0,y1,j0p,j1p,y0p,y1p;
  CRBond_Bessel::bessjy01a(x,j0,j1,y0,y1,j0p,j1p,y0p,y1p);
  
  if (n==0.0)
   {
    return j0;
   }
  else if (n==1.0)
   {
    return j1;
   }
  else
   {
    cout << "Never get here...";
    abort();
   }
 }
 
 /// Exact solution as a Vector
 void exact_u(const Vector<double>& x, Vector<double>& u)
 {
  double r=sqrt(x[0]*x[0]+x[1]*x[1]);
 
  double MapleGenVar1;
  double MapleGenVar2;
  double MapleGenVar3;
  double MapleGenVar4;
  double MapleGenVar5;
  double MapleGenVar6;
  double MapleGenVar7;
  double t0;
 
  double omega=sqrt(Omega_sq);
 
      MapleGenVar3 = Displacement_amplitude*Nu*omega*BesselY(0.0,omega/sqrt(Nu/
(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))+Displacement_amplitude
*Nu*omega*BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(
1.0+H_annulus))*H_annulus-Displacement_amplitude*BesselY(0.0,omega/sqrt(Nu/(1.0
+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega-
Displacement_amplitude*BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0
+2.0*Nu))*(1.0+H_annulus))*omega*H_annulus+Displacement_amplitude*sqrt(-(1.0-Nu
)/(-1.0+Nu+2.0*Nu*Nu))*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0
+2.0*Nu))*(1.0+H_annulus))-2.0*Displacement_amplitude*sqrt(-(1.0-Nu)/(-1.0+Nu+
2.0*Nu*Nu))*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(
1.0+H_annulus))*Nu;
      MapleGenVar2 = MapleGenVar3-BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu)))*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))-BesselY(1.0,omega/
sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*
Nu*Nu))*H_annulus+BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*
Nu)))*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*Nu+BesselY(1.0,omega/sqrt(Nu/(1.0+
Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*Nu*
H_annulus+2.0*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))
)*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*Nu*Nu+2.0*BesselY(1.0,omega/sqrt(Nu/(
1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*
Nu*Nu*H_annulus;
      MapleGenVar7 = Nu*omega*BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+
2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu)))+Nu*omega*BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)
+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*H_annulus*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu
)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))-BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)
/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar6 = MapleGenVar7-BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*H_annulus*BesselJ(1.0,omega/sqrt(
Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))
*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+
H_annulus))*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))
-2.0*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(
1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*Nu*BesselJ(1.0,omega/sqrt(Nu/(
1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar7 = MapleGenVar6+BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)
/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu
)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*H_annulus*BesselY(1.0,omega/sqrt(Nu/
(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar5 = MapleGenVar7-sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselJ(
1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*
BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))-Nu*omega*
BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+
H_annulus))*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+
2.0*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0
-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*Nu*BesselY(1.0,omega/sqrt(Nu/(1.0+
Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))-Nu*omega*BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)
/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*H_annulus*BesselY(1.0,omega/
sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar4 = 1/MapleGenVar5;
      MapleGenVar5 = BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+
2.0*Nu))*r);
      MapleGenVar3 = MapleGenVar4*MapleGenVar5;
      MapleGenVar1 = MapleGenVar2*MapleGenVar3;
      MapleGenVar6 = -Nu*omega*BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+
2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu)))-Nu*omega*BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)
+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*H_annulus*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu
)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)
/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar5 = MapleGenVar6+BesselY(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*H_annulus*BesselJ(1.0,omega/sqrt(
Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))-sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))
*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+
H_annulus))*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+
2.0*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0
-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*Nu*BesselJ(1.0,omega/sqrt(Nu/(1.0+
Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar6 = MapleGenVar5-BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)
/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))-BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu
)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*H_annulus*BesselY(1.0,omega/sqrt(Nu/
(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar4 = MapleGenVar6+sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselJ(
1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*
BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+Nu*omega*
BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+
H_annulus))*BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))
-2.0*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(
1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*Nu*BesselY(1.0,omega/sqrt(Nu/(
1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+Nu*omega*BesselJ(0.0,omega/sqrt(Nu/(1.0
+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*H_annulus*BesselY(1.0,
omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)));
      MapleGenVar3 = 1/MapleGenVar4;
      MapleGenVar6 = -P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselJ(1.0,omega/
sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))-P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*
Nu*Nu))*H_annulus*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*
Nu)))+P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*Nu*BesselJ(1.0,omega/sqrt(Nu/(1.0+
Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*Nu*
H_annulus*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+
2.0*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*Nu*Nu*BesselJ(1.0,omega/sqrt(Nu/(1.0+
Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu)))+2.0*P*sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*
Nu*Nu*H_annulus*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu
)));
      MapleGenVar7 = MapleGenVar6-BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*
Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*Displacement_amplitude-BesselJ(0.0
,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*omega*
H_annulus*Displacement_amplitude;
      MapleGenVar5 = MapleGenVar7+sqrt(-(1.0-Nu)/(-1.0+Nu+2.0*Nu*Nu))*BesselJ(
1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*
Displacement_amplitude+Nu*omega*BesselJ(0.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)
+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*Displacement_amplitude-2.0*sqrt(-(1.0-Nu)/(
-1.0+Nu+2.0*Nu*Nu))*BesselJ(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+
2.0*Nu))*(1.0+H_annulus))*Nu*Displacement_amplitude+Nu*omega*BesselJ(0.0,omega/
sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+2.0*Nu))*(1.0+H_annulus))*H_annulus*
Displacement_amplitude;
      MapleGenVar6 = BesselY(1.0,omega/sqrt(Nu/(1.0+Nu)/(1.0-2.0*Nu)+2.0/(2.0+
2.0*Nu))*r);
      MapleGenVar4 = MapleGenVar5*MapleGenVar6;
      MapleGenVar2 = MapleGenVar3*MapleGenVar4;
      t0 = MapleGenVar1+MapleGenVar2;
 
  
  u[0]=t0*x[0]/r;
  u[1]=t0*x[1]/r;
  
  u[2]=-t0*x[0]/r;
  u[3]=-t0*x[1]/r;
 
 }
 
} //end namespace
 
 
 
//=============begin_problem============================================ 
/// Annular disk
//====================================================================== 
template<class ELASTICITY_ELEMENT>
class AnnularDiskProblem : public Problem
{
 
public:
 
 /// Constructor:
 AnnularDiskProblem();
 
 /// Update function (empty)
 void actions_after_newton_solve() {}
 
 /// Update function (empty)
 void actions_before_newton_solve() {}
 
 /// Actions before adapt: Wipe the mesh of traction elements
 void actions_before_adapt();
 
 /// Actions after adapt: Rebuild the mesh of traction elements
 void actions_after_adapt();
 
 /// Doc the solution
 void doc_solution();
 
private:
 
 /// Create traction elements
 void create_traction_elements();
 
 /// Delete traction elements
 void delete_traction_elements();
 
#ifdef ADAPTIVE
 
 /// Pointer to refineable solid mesh
 TreeBasedRefineableMeshBase* Solid_mesh_pt;
 
#else
 
 /// Pointer to solid mesh
 Mesh* Solid_mesh_pt;
 
#endif
 
 /// Pointer to mesh of traction elements
 Mesh* Traction_mesh_pt;
 
 /// DocInfo object for output
 DocInfo Doc_info;
 
};
 
 
//===========start_of_constructor======================================= 
/// Constructor: 
//====================================================================== 
template<class ELASTICITY_ELEMENT>
AnnularDiskProblem<ELASTICITY_ELEMENT>::AnnularDiskProblem() 
{
 
 // Solid mesh
 //-----------
 
 // The mesh is periodic 
 bool periodic=true;
 
 // Azimuthal fraction of elastic coating
 double azimuthal_fraction_of_coating=1.0;
 
 // Innermost radius for solid mesh
 double a=1.0;
 
 // Gap in annulus?
 if (CommandLineArgs::command_line_flag_has_been_set("--have_gap"))
  {
   periodic=false;
   azimuthal_fraction_of_coating=0.9;
  }
 
#ifdef ADAPTIVE
 
 // Build solid mesh
 Solid_mesh_pt = new 
  RefineableTwoDAnnularMesh<ELASTICITY_ELEMENT>(
   periodic,azimuthal_fraction_of_coating,
   Global_Parameters::Ntheta,
   Global_Parameters::Nr,a,
   Global_Parameters::H_annulus);
 
 // Set error estimators
 Solid_mesh_pt->spatial_error_estimator_pt()=new Z2ErrorEstimator;
 
 // Set some refinement targets
 Solid_mesh_pt->max_refinement_level()=2;
 
#else
 
 // Build solid mesh
 Solid_mesh_pt = new 
  TwoDAnnularMesh<ELASTICITY_ELEMENT>(
   periodic,azimuthal_fraction_of_coating,
   Global_Parameters::Ntheta,
   Global_Parameters::Nr,a,
   Global_Parameters::H_annulus);
 
#endif
 
 // Let's have a look where the boundaries are
 Solid_mesh_pt->output("solid_mesh.dat");
 Solid_mesh_pt->output_boundaries("solid_mesh_boundary.dat");
 
 
 //Assign the physical properties to the elements
 //Loop over the elements in the main mesh
 unsigned n_element =Solid_mesh_pt->nelement();
 for(unsigned i=0;i<n_element;i++)
  {
   //Cast to a solid element
   ELASTICITY_ELEMENT *el_pt = 
    dynamic_cast<ELASTICITY_ELEMENT*>(Solid_mesh_pt->element_pt(i));
   
   // Set the constitutive law
   el_pt->elasticity_tensor_pt() = &Global_Parameters::E;
 
   // Square of non-dim frequency
   el_pt->omega_sq_pt()= &Global_Parameters::Omega_sq;
  }
 
 // Construct the traction element mesh
 Traction_mesh_pt=new Mesh;
 create_traction_elements(); 
 
 // Solid mesh is first sub-mesh
 add_sub_mesh(Solid_mesh_pt);
 
 // Add traction sub-mesh
 add_sub_mesh(Traction_mesh_pt);
 
 // Build combined "global" mesh
 build_global_mesh();
 
 // Solid boundary conditions:
 //---------------------------
 
 // Pin real and imag part of both displacement components 
 // on the inner (boundary 0)
 unsigned b_inner=0;
 unsigned n_node = Solid_mesh_pt->nboundary_node(b_inner);
 
 //Loop over the nodes to pin and assign boundary displacements on 
 //solid boundary
 Vector<double> u(2);
 Vector<double> x(2);
 for(unsigned i=0;i<n_node;i++)
  {
   Node* nod_pt=Solid_mesh_pt->boundary_node_pt(b_inner,i);
   nod_pt->pin(0);
   nod_pt->pin(1);
   nod_pt->pin(2);
   nod_pt->pin(3);
   
   // Assign displacements
   x[0]=nod_pt->x(0);   
   x[1]=nod_pt->x(1);   
   Global_Parameters::solid_boundary_displacement(x,u);
 
   // Real part of x-displacement
   nod_pt->set_value(0,u[0]);
   // Real part of y-displacement
   nod_pt->set_value(1,u[1]);
   // Imag part of x-displacement
   nod_pt->set_value(2,-u[0]);
   // Imag part of y-displacement
   nod_pt->set_value(3,-u[1]);
  }
 
 //Assign equation numbers
 cout << assign_eqn_numbers() << std::endl; 
 
 // Set output directory
 Doc_info.set_directory(Global_Parameters::Directory);
 
} //end_of_constructor
 
 
 
 
//=====================start_of_actions_before_adapt======================
/// Actions before adapt: Wipe the mesh of traction elements
//========================================================================
template<class ELASTICITY_ELEMENT>
void AnnularDiskProblem<ELASTICITY_ELEMENT>::actions_before_adapt()
{
 // Kill the traction elements and wipe surface mesh
 delete_traction_elements();
 
 // Rebuild the Problem's global mesh from its various sub-meshes
 rebuild_global_mesh();
 
}// end of actions_before_adapt
 
 
 
//=====================start_of_actions_after_adapt=======================
///  Actions after adapt: Rebuild the mesh of traction elements
//========================================================================
template<class ELASTICITY_ELEMENT>
void AnnularDiskProblem<ELASTICITY_ELEMENT>::actions_after_adapt()
{
 // Create traction elements from all elements that are 
 // adjacent to FSI boundaries and add them to surface meshes
 create_traction_elements();
 
 // Rebuild the Problem's global mesh from its various sub-meshes
 rebuild_global_mesh();
 
}// end of actions_after_adapt
 
 
//============start_of_create_traction_elements==============================
/// Create traction elements 
//=======================================================================
template<class ELASTICITY_ELEMENT>
void AnnularDiskProblem<ELASTICITY_ELEMENT>::create_traction_elements()
{
 
 // Load outer surface (2) and both "ends" (1 and 3) if there's a gap
 unsigned b_lo=1;
 unsigned b_hi=3;
 
 // ...otherwise load only the outside (2)
 if (!CommandLineArgs::command_line_flag_has_been_set("--have_gap"))
  {     
   b_lo=2;
   b_hi=2;
  }
 
 for (unsigned b=b_lo;b<=b_hi;b++)
  {
   // How many bulk elements are adjacent to boundary b?
   unsigned n_element = Solid_mesh_pt->nboundary_element(b);
   
   // Loop over the bulk elements adjacent to boundary b
   for(unsigned e=0;e<n_element;e++)
    {
     // Get pointer to the bulk element that is adjacent to boundary b
     ELASTICITY_ELEMENT* bulk_elem_pt = dynamic_cast<ELASTICITY_ELEMENT*>(
      Solid_mesh_pt->boundary_element_pt(b,e));
     
     //Find the index of the face of element e along boundary b
     int face_index = Solid_mesh_pt->face_index_at_boundary(b,e);
     
     // Create element
     TimeHarmonicLinearElasticityTractionElement<ELASTICITY_ELEMENT>* el_pt=
      new TimeHarmonicLinearElasticityTractionElement<ELASTICITY_ELEMENT>
      (bulk_elem_pt,face_index);   
 
     // Add to mesh
     Traction_mesh_pt->add_element_pt(el_pt);
     
     // Associate element with bulk boundary (to allow it to access
     // the boundary coordinates in the bulk mesh)
     el_pt->set_boundary_number_in_bulk_mesh(b); 
     
     //Set the traction function
     el_pt->traction_fct_pt() = Global_Parameters::constant_pressure;
    }
  }
 
} // end_of_create_traction_elements
 
 
 
 
//============start_of_delete_traction_elements==============================
/// Delete traction elements and wipe the  traction meshes
//=======================================================================
template<class ELASTICITY_ELEMENT>
void AnnularDiskProblem<ELASTICITY_ELEMENT>::delete_traction_elements()
{
 // How many surface elements are in the surface mesh
 unsigned n_element = Traction_mesh_pt->nelement();
 
 // Loop over the surface elements
 for(unsigned e=0;e<n_element;e++)
  {
   // Kill surface element
   delete Traction_mesh_pt->element_pt(e);
  }
 
 // Wipe the mesh
 Traction_mesh_pt->flush_element_and_node_storage();
 
} // end of delete_traction_elements
 
 
 
 
 
//==============start_doc===========================================
/// Doc the solution
//==================================================================
template<class ELASTICITY_ELEMENT>
void AnnularDiskProblem<ELASTICITY_ELEMENT>::doc_solution()
{
 
 ofstream some_file;
 char filename[100];
 
 // Number of plot points
 unsigned n_plot=5; 
 
 // Output displacement field
 //--------------------------
 sprintf(filename,"%s/elast_soln%i.dat",Doc_info.directory().c_str(),
         Doc_info.number());
 some_file.open(filename);
 Solid_mesh_pt->output(some_file,n_plot);
 some_file.close();
 
 
 // Output traction elements
 //-------------------------
 sprintf(filename,"%s/traction_soln%i.dat",Doc_info.directory().c_str(),
         Doc_info.number());
 some_file.open(filename);
 Traction_mesh_pt->output(some_file,n_plot);
 some_file.close();
 
 // Output exact solution 
 //----------------------
 sprintf(filename,"%s/exact_soln%i.dat",Doc_info.directory().c_str(),
         Doc_info.number());
 some_file.open(filename);
 Solid_mesh_pt->output_fct(some_file,n_plot,Global_Parameters::exact_u); 
 some_file.close();
 
 // Increment label for output files
 Doc_info.number()++;
 
} //end doc
 
 
 
//=======start_of_main==================================================
/// Driver for annular disk loaded by pressure
//======================================================================
int main(int argc, char **argv)
{
 
 // Store command line arguments
 CommandLineArgs::setup(argc,argv);
 
 // Define possible command line arguments and parse the ones that
 // were actually specified
 
 // Number of elements in azimuthal direction
 CommandLineArgs::specify_command_line_flag(
  "--ntheta",
  &Global_Parameters::Ntheta);
 
 // Number of elements in radial direction
 CommandLineArgs::specify_command_line_flag(
  "--nr",
  &Global_Parameters::Nr);
 
 // Do have a gap in the annulus?
 CommandLineArgs::specify_command_line_flag("--have_gap");
  
#ifdef ADAPTIVE
 
 // Max. number of adaptations
 unsigned max_adapt=3;
 CommandLineArgs::specify_command_line_flag("--max_adapt",&max_adapt);
 
 // Number of uniform refinements
 unsigned nrefine=0; 
 CommandLineArgs::specify_command_line_flag("--nrefine",&nrefine);
 
#endif
 
 // P increment
 double p_increment=0.1;
 CommandLineArgs::specify_command_line_flag("--p_increment",&p_increment);
 
 // Number of steps
 unsigned nstep=3; 
 CommandLineArgs::specify_command_line_flag("--nstep",&nstep);
 
 // Parse command line
 CommandLineArgs::parse_and_assign(); 
 
 // Doc what has actually been specified on the command line
 CommandLineArgs::doc_specified_flags();
 
#ifdef ADAPTIVE
 
 //Set up the problem
 AnnularDiskProblem<RefineableQTimeHarmonicLinearElasticityElement<2,3> >
  problem;
 
 // Refine unformly
 for (unsigned i=0;i<nrefine;i++)
  {
   problem.refine_uniformly();
  }
 
#else
 
 //Set up the problem
 AnnularDiskProblem<QTimeHarmonicLinearElasticityElement<2,3> > problem;
 
#endif
 
 
 // Initial values for parameter values
 Global_Parameters::P=0.0; 
 
 //Parameter incrementation
 for(unsigned i=0;i<nstep;i++)
  {
 
#ifdef ADAPTIVE
 
   // Solve the problem with Newton's method, allowing
   // up to max_adapt mesh adaptations after every solve.
   problem.newton_solve(max_adapt);
 
#else
 
   // Solve the problem using Newton's method
   problem.newton_solve();
 
#endif
   
   // Doc solution
   problem.doc_solution();
   
   // Increment pressure
   Global_Parameters::P+=p_increment;
  }
 
} //end of main