two_layer_spine_mesh.h

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// LIC// ====================================================================
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// LIC// multi-physics finite-element library, available
// LIC// at http://www.oomph-lib.org.
// LIC//
// LIC// Copyright (C) 2006-2025 Matthias Heil and Andrew Hazel
// LIC//
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#ifndef OOMPH_TWO_LAYER_SPINE_MESH_HEADER
#define OOMPH_TWO_LAYER_SPINE_MESH_HEADER
 
// The mesh
#include "generic/spines.h"
#include "rectangular_quadmesh.h"
 
namespace oomph
{
  //======================================================================
  /// Two-layer spine mesh class derived from standard 2D mesh.
  /// The mesh contains two layers of spinified fluid elements (of type ELEMENT;
  /// e.g  SpineElement<QCrouzeixRaviartElement<2>).
  ///
  /// This mesh paritions the elements into those above and below a
  /// notional interface and relabels boundaries so that the mesh is as follows
  ///                                 3
  ///               ---------------------------------------
  ///               |                                     |
  ///             4 |                                     | 2
  ///               |                 6                   |
  ///               ---------------------------------------
  ///               |                                     |
  ///             5 |                                     | 1
  ///               |                                     |
  ///               ---------------------------------------
  ///                                  0
  /// Update information for the nodes in response to changes in spine length
  /// is given, but additional equations must be specified in order to
  /// completely specify the problem.
  //======================================================================
  template<class ELEMENT>
  class TwoLayerSpineMesh : public RectangularQuadMesh<ELEMENT>,
                            public SpineMesh
  {
  public:
    /// Constructor: Pass number of elements in x-direction, number of
    /// elements in y-direction in bottom and top layer, respectively,
    /// axial length and height of top and bottom layers and pointer
    /// to timestepper (defaults to Steady timestepper)
    TwoLayerSpineMesh(
      const unsigned& nx,
      const unsigned& ny1,
      const unsigned& ny2,
      const double& lx,
      const double& h1,
      const double& h2,
      TimeStepper* time_stepper_pt = &Mesh::Default_TimeStepper);
 
 
    /// Constructor: Pass number of elements in x-direction, number of
    /// elements in y-direction in bottom and top layer, respectively,
    /// axial length and height of top and bottom layers, a boolean
    /// flag to make the mesh periodic in the x-direction, and pointer
    /// to timestepper (defaults to Steady timestepper)
    TwoLayerSpineMesh(
      const unsigned& nx,
      const unsigned& ny1,
      const unsigned& ny2,
      const double& lx,
      const double& h1,
      const double& h2,
      const bool& periodic_in_x,
      TimeStepper* time_stepper_pt = &Mesh::Default_TimeStepper);
 
 
    /// Constructor: Pass number of elements in x-direction, number of
    /// elements in y-direction in bottom and top layer, respectively,
    /// axial length and height of top and bottom layers, a boolean
    /// flag to make the mesh periodic in the x-direction, a boolean flag to
    /// specify whether or not to call the "build_two_layer_mesh" function,
    /// and pointer to timestepper (defaults to Steady timestepper)
    TwoLayerSpineMesh(
      const unsigned& nx,
      const unsigned& ny1,
      const unsigned& ny2,
      const double& lx,
      const double& h1,
      const double& h2,
      const bool& periodic_in_x,
      const bool& build_mesh,
      TimeStepper* time_stepper_pt = &Mesh::Default_TimeStepper);
 
    /// Access functions for pointers to elements in upper layer
    FiniteElement*& upper_layer_element_pt(const unsigned long& i)
    {
      return Upper_layer_element_pt[i];
    }
 
    /// Access functions for pointers to elements in bottom layer
    FiniteElement*& lower_layer_element_pt(const unsigned long& i)
    {
      return Lower_layer_element_pt[i];
    }
 
    /// Number of elements in upper layer
    unsigned long nupper() const
    {
      return Upper_layer_element_pt.size();
    }
 
    /// Number of elements in top layer
    unsigned long nlower() const
    {
      return Lower_layer_element_pt.size();
    }
 
    /// Access functions for pointers to elements in upper layer
    FiniteElement*& interface_upper_boundary_element_pt(const unsigned long& i)
    {
      return Interface_upper_boundary_element_pt[i];
    }
 
    /// Access functions for pointers to elements in bottom layer
    FiniteElement*& interface_lower_boundary_element_pt(const unsigned long& i)
    {
      return Interface_lower_boundary_element_pt[i];
    }
 
    /// Number of elements in upper layer
    unsigned long ninterface_upper() const
    {
      return Interface_upper_boundary_element_pt.size();
    }
 
    /// Number of elements in top layer
    unsigned long ninterface_lower() const
    {
      return Interface_lower_boundary_element_pt.size();
    }
 
    /// Index of the face of the elements next to the interface
    /// in the upper region (always -2)
    int interface_upper_face_index_at_boundary(const unsigned& e)
    {
      return -2;
    }
 
    /// Index of the face of the elements next to the interface in
    /// the lower region (always 2)
    int interface_lower_face_index_at_boundary(const unsigned& e)
    {
      return 2;
    }
 
    /// General node update function implements pure virtual function
    /// defined in SpineMesh base class and performs specific update
    /// actions, depending on the node update fct id stored for each node.
    void spine_node_update(SpineNode* spine_node_pt)
    {
      unsigned id = spine_node_pt->node_update_fct_id();
      switch (id)
      {
        case 0:
          spine_node_update_lower(spine_node_pt);
          break;
 
        case 1:
          spine_node_update_upper(spine_node_pt);
          break;
 
        default:
          std::ostringstream error_message;
          error_message << "Unknown id passed to spine_node_update " << id
                        << std::endl;
          throw OomphLibError(error_message.str(),
                              OOMPH_CURRENT_FUNCTION,
                              OOMPH_EXCEPTION_LOCATION);
      }
    }
 
  protected:
    /// Number of elements in lower layer
    unsigned Ny1;
 
    /// Number of elements in upper layer
    unsigned Ny2;
 
    ///  Height of the lower layer
    double H1;
 
    ///  Height of the upper layer
    double H2;
 
    /// Vector of pointers to element in the upper layer
    Vector<FiniteElement*> Lower_layer_element_pt;
 
    /// Vector of pointers to element in the lower layer
    Vector<FiniteElement*> Upper_layer_element_pt;
 
    /// Vector of pointers to the elements adjacent to the interface
    /// on the lower layer
    Vector<FiniteElement*> Interface_lower_boundary_element_pt;
 
    /// Vector of pointers to the element adjacent to the interface
    /// on the upper layer
    Vector<FiniteElement*> Interface_upper_boundary_element_pt;
 
 
    /// The spacing function for the x co-ordinates with two
    /// regions.
    double x_spacing_function(unsigned xelement,
                              unsigned xnode,
                              unsigned yelement,
                              unsigned ynode);
 
    /// The spacing function for the y co-ordinates with three
    /// regions in each fluid.
    double y_spacing_function(unsigned xelement,
                              unsigned xnode,
                              unsigned yelement,
                              unsigned ynode);
 
    /// Update function for the lower part of the domain
    void spine_node_update_lower(SpineNode* spine_node_pt)
    {
      // Get fraction along the spine
      double W = spine_node_pt->fraction();
      // Get spine height
      double H = spine_node_pt->h();
      // Set the value of y
      spine_node_pt->x(1) = this->Ymin + W * H;
    }
 
 
    /// Update function for the upper part of the domain
    void spine_node_update_upper(SpineNode* spine_node_pt)
    {
      // Get fraction alon the spine
      double W = spine_node_pt->fraction();
 
      // Get spine height
      double H = spine_node_pt->h();
 
      // Set the value of y
      spine_node_pt->x(1) =
        (this->Ymin + H) + W * (this->Ymax - (this->Ymin + H));
    }
 
    /// Helper function to actually build the two-layer spine mesh
    /// (called from various constructors)
    virtual void build_two_layer_mesh(TimeStepper* time_stepper_pt);
  };
 
} // namespace oomph
 
#include "two_layer_spine_mesh.template.cc"
#endif