advectiondiffusionlatticedescriptors.h

open lattice boltzmann project www.openlb.org

/*  This file is part of the OpenLB library
 *
 *  Copyright (C) 2008 Orestis Malaspinas, Andrea Parmigiani
 *  Address: EPFL-STI-LIN Station 9, 1015 Lausanne
 *  E-mail: [e-mail]
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public 
 *  License along with this program; if not, write to the Free 
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA  02110-1301, USA.
*/

/** \file
 * Descriptor for all types of 2D and 3D lattices. In principle, thanks
 * to the fact that the OpenLB code is generic, it is sufficient to
 * write a new descriptor when a new type of lattice is to be used.
 *  -- header file
 */
#ifndef ADVECTION_DIFFUSION_LATTICE_DESCRIPTORS_H
#define ADVECTION_DIFFUSION_LATTICE_DESCRIPTORS_H

#include <vector>
#include "core/latticeDescriptors.h"

namespace olb {

/// Descriptors for the 2D and 3D lattices.
/** \warning Attention: The lattice directions must always be ordered in
 * such a way that c[i] = -c[i+(q-1)/2] for i=1..(q-1)/2, and c[0] = 0 must
 * be the rest velocity. Furthermore, the velocities c[i] for i=1..(q-1)/2
 * must verify
 *  - in 2D: (c[i][0]<0) || (c[i][0]==0 && c[i][1]<0)
 *  - in 3D: (c[i][0]<0) || (c[i][0]==0 && c[i][1]<0)
 *                       || (c[i][0]==0 && c[i][1]==0 && c[i][2]<0)
 * Otherwise some of the code will work erroneously, because the
 * aformentioned relations are taken as given to enable a few
 * optimizations.
*/
namespace descriptors 
{
//===========================================================================//
//=================== AdvectionDiffusion Lattice Descriptors=================//
//===========================================================================//
    
    /// D2Q5 lattice
    template <typename T> struct D2Q5DescriptorBase
    {
        typedef D2Q5DescriptorBase<T> BaseDescriptor;
        enum { d = 2, q = 5 };      ///< number of dimensions/distr. functions
        static const int c[q][d];   ///< lattice directions
        static const T t[q];        ///< lattice weights
        static const T invCs2;      ///< inverse square of speed of sound
    };
    
    struct Velocity2dDescriptor {
        static const int numScalars = 2;
        static const int numSpecies = 1;
        static const int velocityBeginsAt = 0;
        static const int sizeOfVelocity   = 2;
    };
    
    struct Velocity2dBase {
        typedef Velocity2dDescriptor ExternalField;
    };
    
    struct Velocity3dDescriptor {
        static const int numScalars = 3;
        static const int numSpecies = 1;
        static const int velocityBeginsAt = 0;
        static const int sizeOfVelocity   = 3;
    };
    
    struct Velocity3dBase {
        typedef Velocity3dDescriptor ExternalField;
    };
    
    /// AD D2Q5 lattice
    template <typename T> struct AdvectionDiffusionD2Q5Descriptor
        : public D2Q5DescriptorBase<T>, public Velocity2dBase
    {  };
    
    /// D3Q7 lattice
    template <typename T> struct D3Q7DescriptorBase {
        typedef D3Q7DescriptorBase<T> BaseDescriptor;
        enum { d = 3, q = 7 };     ///< number of dimensions/distr. functions
        static const int c[q][d];   ///< lattice directions
        static const T t[q];        ///< lattice weights
        static const T invCs2;      ///< inverse square of speed of sound
    };

    template <typename T> struct AdvectionDiffusionD3Q7Descriptor 
    : public D3Q7DescriptorBase<T>, public Velocity3dBase
    {  };

}  // namespace descriptors

}  // namespace olb

#endif