inf_elem_builder.h

一个用来实现偏微分方程中网格的计算库

// $Id: inf_elem_builder.h 2501 2007-11-20 02:33:29Z benkirk $

// The libMesh Finite Element Library.
// Copyright (C) 2002-2007  Benjamin S. Kirk, John W. Peterson
  
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
  
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
  
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

#ifndef __inf_elem_builder_h__
#define __inf_elem_builder_h__


#include "libmesh_config.h"


#ifdef ENABLE_INFINITE_ELEMENTS

// C++ includes
#include <vector>
#include <set>
#include <utility>

// Local includes
#include "point.h"

// Forward Declarations
class MeshBase;
class Node;

/**
 * This class is used to build infinite elements on
 * top of an existing mesh.  It only makes sense to
 * use this if ENABLE_INFINITE_ELEMENTS is true.
 *
 * @author original code by Daniel Dreyer, converted
 * to InfElemBuilder class by John W. Peterson, 2004.
 */
class InfElemBuilder
{
public:
  /**
   * Constructor.
   */
  InfElemBuilder(MeshBase& mesh) : _mesh(mesh) {}

  /**
   * Useful typedef
   */
  typedef std::pair<bool, double> InfElemOriginValue;

  /**
   * Build infinite elements atop a volume-based mesh,
   * determine origin automatically.  Also returns the
   * origin as a \p const \p Point to make it more obvious that
   * the origin should not change after the infinite elements 
   * have been built.  When symmetry planes are present, use 
   * the version with optional symmetry switches.  
   * The flag \p be_verbose enables some diagnostic output.
   */
  const Point build_inf_elem (const bool be_verbose = false);

  /**
   * @returns the origin of the infinite elements.
   * Builds infinite elements atop a volume-based mesh.
   * Finds all faces on the outer boundary and build infinite elements
   * on them.  Using the \p InfElemOriginValue the user can
   * prescribe only selected origin coordinates.  The remaining
   * coordinates are computed from the center of the bounding box
   * of the mesh.
   *
   * During the search for faces on which infinite elements are built, 
   * @e interior faces that are not on symmetry planes are found, too.  
   * When an (optional) pointer to \p inner_boundary_nodes is provided, 
   * then this vector will be filled with the nodes that lie on the
   * inner boundary.
   *
   * Faces which lie in at least one symmetry plane are skipped.
   * The three optional booleans \p x_sym, \p y_sym,
   * \p z_sym indicate symmetry planes (through the origin, obviously)
   * perpendicular to the \p x, \p y and \p z direction, 
   * respectively.  
   * The flag \p be_verbose enables some diagnostic output.
   */
  const Point build_inf_elem (const InfElemOriginValue& origin_x,
			      const InfElemOriginValue& origin_y,
			      const InfElemOriginValue& origin_z,
			      const bool x_sym = false,
			      const bool y_sym = false,
			      const bool z_sym = false,
			      const bool be_verbose = false,
			      std::vector<const Node*>* inner_boundary_nodes = NULL);



private:
  /**
   * Build infinite elements atop a volume-based mesh.
   * Actual implementation.
   */
  void build_inf_elem (const Point& origin,
		       const bool x_sym = false,
		       const bool y_sym = false,
		       const bool z_sym = false,
		       const bool be_verbose = false,
		       std::set<std::pair<unsigned int,
		                          unsigned int> >* inner_faces = NULL);
  /**
   * Reference to the mesh we're building infinite
   * elements for.
   */
  MeshBase& _mesh;
};


#endif // ENABLE_INFINITE_ELEMENTS
#endif