ETA_VectorialADR2DTest.cpp

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/*
*******************************************************************************

    Copyright (C) 2004, 2005, 2007 EPFL, Politecnico di Milano, INRIA
    Copyright (C) 2010 EPFL, Politecnico di Milano, Emory University

    This file is part of LifeV.

    LifeV is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
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    along with LifeV.  If not, see <http://www.gnu.org/licenses/>.

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//@HEADER
/**
   @file ETA_VectorialADR2DTest.cpp
   @author L. Pasquale <luca.pasquale@mail.polimi.it>
   @date 2012-11-20
 */

// ===================================================
//! Includes
// ===================================================

#include "ETA_VectorialADR2DTest.hpp"

#include <lifev/eta/fem/ETFESpace.hpp>
#include <lifev/eta/expression/Integrate.hpp>


// ===================================================
//! Namespaces & define
// ===================================================

// ---------------------------------------------------------------
// We work in the LifeV namespace and define the mesh, matrix and
// vector types that we will need several times.
// ---------------------------------------------------------------

using namespace LifeV;

typedef RegionMesh<LinearTriangle> mesh_Type;
typedef MatrixEpetra<Real> matrix_Type;
typedef VectorEpetra vector_Type;

// ---------------------------------------------------------------
// We define then a function, which represents a velocity field,
// of magnitude 1 in the y direction (supposing an (x,y)
// reference frame).
// ---------------------------------------------------------------


// ===================================================
//!                   Functions
// ===================================================

Real betaFct ( const Real& /* t */, const Real& /* x */, const Real& /* y */, const Real& /* z */, const ID& i )
{
    if (i == 1)
    {
        return 1;
    }
    return 0;
}

// ===================================================
//!                  Constructors
// ===================================================

ETA_VectorialADR2DTest::ETA_VectorialADR2DTest ()
{

#ifdef EPETRA_MPI
    M_comm.reset ( new Epetra_MpiComm ( MPI_COMM_WORLD ) );
#else
    M_comm.reset ( new Epetra_SerialComm() );
#endif

}

// ===================================================
//!                      Methods
// ===================================================

Real
ETA_VectorialADR2DTest::run()
{
    bool verbose (M_comm->MyPID() == 0);
    // ---------------------------------------------------------------
    // We define the mesh and parition it. We use the domain
    // (-1,1)x(-1,1) and a structured mesh.
    // ---------------------------------------------------------------

    if (verbose)
    {
        std::cout << " -- Building and partitioning the mesh ... " << std::flush;
    }

    const UInt Nelements (10);

    std::shared_ptr< mesh_Type > fullMeshPtr (new mesh_Type);

    regularMesh2D ( *fullMeshPtr, 0, Nelements, Nelements, false,
                    2.0,   2.0,
                    -0.0,  -0.0);

    std::shared_ptr< mesh_Type > meshPtr;
    {
        MeshPartitioner< mesh_Type >   meshPart (fullMeshPtr, M_comm);
        meshPtr = meshPart.meshPartition();
    }

    fullMeshPtr.reset();

    if (verbose)
    {
        std::cout << " done ! " << std::endl;
    }


    // ---------------------------------------------------------------
    // We start by defining the finite element spaces. We use the type
    // FESpace for the classical way and copy it in an ETFESpace for
    // the ET assembly.
    //
    // In the end, both solution spaces display their respective
    // number of degrees of freedom, which must be the same.
    // ---------------------------------------------------------------

    if (verbose)
    {
        std::cout << " -- Building FESpaces ... " << std::flush;
    }

    std::string uOrder ("P1");
    std::string bOrder ("P1");

    std::shared_ptr<FESpace< mesh_Type, MapEpetra > > uSpace
    ( new FESpace< mesh_Type, MapEpetra > (meshPtr, uOrder, 2, M_comm) );

    std::shared_ptr<FESpace< mesh_Type, MapEpetra > > betaSpace
    ( new FESpace< mesh_Type, MapEpetra > (meshPtr, bOrder, 2, M_comm) );

    if (verbose)
    {
        std::cout << " done ! " << std::endl;
    }
    if (verbose)
    {
        std::cout << " ---> Dofs: " << uSpace->dof().numTotalDof() << std::endl;
    }

    if (verbose)
    {
        std::cout << " -- Building ETFESpaces ... " << std::flush;
    }

    std::shared_ptr<ETFESpace< mesh_Type, MapEpetra, 2, 2 > > ETuSpace
    ( new ETFESpace< mesh_Type, MapEpetra, 2, 2 > (meshPtr, & (uSpace->refFE() ), & (uSpace->fe().geoMap() ), M_comm) );

    std::shared_ptr<ETFESpace< mesh_Type, MapEpetra, 2, 2 > > ETbetaSpace
    ( new ETFESpace< mesh_Type, MapEpetra, 2, 2 > (meshPtr, & (betaSpace->refFE() ), & (betaSpace->fe().geoMap() ), M_comm) );

    if (verbose)
    {
        std::cout << " done ! " << std::endl;
    }
    if (verbose)
    {
        std::cout << " ---> Dofs: " << ETuSpace->dof().numTotalDof() << std::endl;
    }


    // ---------------------------------------------------------------
    // We interpolate then the advection function of the mesh at hand.
    // This is performed with the classical FESpace only.
    // ---------------------------------------------------------------

    if (verbose)
    {
        std::cout << " -- Interpolating the advection field ... " << std::flush;
    }

    vector_Type beta (betaSpace->map(), Repeated);
    betaSpace->interpolate (static_cast<FESpace< mesh_Type, MapEpetra >::function_Type> (betaFct), beta, 0.0);

    if (verbose)
    {
        std::cout << " done! " << std::endl;
    }


    // ---------------------------------------------------------------
    // We build now two matrices, one for each assembly procedure in
    // order to compare them in the end. There is no difference in the
    // construction of the matrices.
    // ---------------------------------------------------------------

    if (verbose)
    {
        std::cout << " -- Defining the matrices ... " << std::flush;
    }

    std::shared_ptr<matrix_Type> systemMatrix (new matrix_Type ( uSpace->map() ) );
    *systemMatrix *= 0.0;

    std::shared_ptr<matrix_Type> ETsystemMatrix (new matrix_Type ( ETuSpace->map() ) );
    *ETsystemMatrix *= 0.0;

    if (verbose)
    {
        std::cout << " done! " << std::endl;
    }


    // ---------------------------------------------------------------
    // We come now to the assembly itself. We start with the classical
    // way, which consists in instentiating an ADRAssembler and call
    // the different methods from that class.
    //
    // Using a LifeChrono, we monitor the time required for the
    // assembly.
    //
    // The terms assembled correspond, in the order of appearance, to
    // - a laplacian term
    // - an advection term
    // - a reaction term (with coefficient 2.0), aka mass term.
    // ---------------------------------------------------------------

    LifeChrono StdChrono;
    StdChrono.start();

    if (verbose)
    {
        std::cout << " -- Classical assembly ... " << std::flush;
    }

    ADRAssembler<mesh_Type, matrix_Type, vector_Type> adrAssembler;

    adrAssembler.setup (uSpace, betaSpace);

    adrAssembler.addDiffusion (systemMatrix, 1.0);

    adrAssembler.addAdvection (systemMatrix, beta);

    adrAssembler.addMass (systemMatrix, 2.0);

    StdChrono.stop();

    if (verbose)
    {
        std::cout << " done ! " << std::endl;
    }
    if (verbose)
    {
        std::cout << " Time : " << StdChrono.diff() << std::endl;
    }


    // ---------------------------------------------------------------
    // We perform now the same assembly with the ET assembly and still
    // monitor the timings required.
    //
    // Remark also that the Real constants and VectorSmall constants
    // can be used directly in the expressions to integrate.
    // ---------------------------------------------------------------

    LifeChrono ETChrono;
    ETChrono.start();

    if (verbose)
    {
        std::cout << " -- ET assembly ... " << std::flush;
    }


    {
        using namespace ExpressionAssembly;

        integrate ( elements (ETuSpace->mesh() ),
                    uSpace->qr(),
                    ETuSpace,
                    ETuSpace,

                    dot ( grad (phi_i) , grad (phi_j) )
                    + dot ( grad (phi_j) * value (ETbetaSpace, beta), phi_i)
                    + 2.0 * dot (phi_i, phi_j)

                  )
                >> ETsystemMatrix;

    }

    ETChrono.stop();

    if (verbose)
    {
        std::cout << " done! " << std::endl;
    }
    if (verbose)
    {
        std::cout << " Time : " << ETChrono.diff() << std::endl;
    }


    // ---------------------------------------------------------------
    // We finally need to check that both yield the same matrix. In
    // that aim, we need to finalize both matrices.
    // ---------------------------------------------------------------

    if (verbose)
    {
        std::cout << " -- Closing the matrices ... " << std::flush;
    }

    systemMatrix->globalAssemble();
    ETsystemMatrix->globalAssemble();

    if (verbose)
    {
        std::cout << " done ! " << std::endl;
    }

    // ---------------------------------------------------------------
    // We compute now the matrix of the difference and finally the
    // norm of the difference. This should be very low if the two
    // matrices are identical.
    // ---------------------------------------------------------------

    if (verbose)
    {
        std::cout << " -- Computing the error ... " << std::flush;
    }

    std::shared_ptr<matrix_Type> checkMatrix (new matrix_Type ( ETuSpace->map() ) );
    *checkMatrix *= 0.0;

    *checkMatrix += *systemMatrix;
    *checkMatrix += (*ETsystemMatrix) * (-1);

    checkMatrix->globalAssemble();

    Real errorNorm ( checkMatrix->normInf() );

    if (verbose)
    {
        std::cout << " done ! " << std::endl;
    }



    // ---------------------------------------------------------------
    // We finally display the error norm and compare with the
    // tolerance of the test.
    // ---------------------------------------------------------------

    if (verbose)
    {
        std::cout << " Matrix Error : " << errorNorm << std::endl;
    }

    return errorNorm;

} // run