ForcingNoise.cpp

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///////////////////////////////////////////////////////////////////////////////
//
// File: ForcingNoise.cpp
//
// For more information, please see: http://www.nektar.info
//
// The MIT License
//
// Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
// Department of Aeronautics, Imperial College London (UK), and Scientific
// Computing and Imaging Institute, University of Utah (USA).
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// Description: white noise forcing
//
///////////////////////////////////////////////////////////////////////////////
 
#include <MultiRegions/ExpList.h>
#include <SolverUtils/Forcing/ForcingNoise.h>
 
namespace Nektar::SolverUtils
{
 
std::string ForcingNoise::className =
    GetForcingFactory().RegisterCreatorFunction("Noise", ForcingNoise::create,
                                                "White Noise Forcing");
 
ForcingNoise::ForcingNoise(const LibUtilities::SessionReaderSharedPtr &pSession,
                           const std::weak_ptr<EquationSystem> &pEquation)
    : Forcing(pSession, pEquation)
{
}
 
void ForcingNoise::v_InitObject(
    const Array<OneD, MultiRegions::ExpListSharedPtr> &pFields,
    const unsigned int &pNumForcingFields, const TiXmlElement *pForce)
{
    m_NumVariable = pNumForcingFields;
    int nq        = pFields[0]->GetTotPoints();
 
    const TiXmlElement *noiseElmt = pForce->FirstChildElement("WHITENOISE");
    ASSERTL0(noiseElmt, "Requires WHITENOISE tag specifying "
                        "magnitude of white noise force.");
 
    std::string noiseValue = noiseElmt->GetText();
 
    m_noise = std::stod(noiseValue);
 
    // Load optional parameters
    const TiXmlElement *freqElmt = pForce->FirstChildElement("UPDATEFREQ");
    if (freqElmt)
    {
        std::string freqValue = freqElmt->GetText();
        m_updateFreq          = std::stoi(freqValue);
    }
    else
    {
        // Default is 0 (never update forcing)
        m_updateFreq = 0;
    }
 
    const TiXmlElement *stepsElmt = pForce->FirstChildElement("NSTEPS");
    if (stepsElmt)
    {
        std::string stepsValue = stepsElmt->GetText();
        m_numSteps             = std::stoi(stepsValue);
    }
    else
    {
        // Default is 0 (use noise in the entire simulation)
        m_numSteps = 0;
    }
 
    m_Forcing = Array<OneD, Array<OneD, NekDouble>>(m_NumVariable);
 
    // Fill forcing: use rank in seed to avoid repeated results
    int seed     = -m_session->GetComm()->GetRank();
    m_Forcing[0] = Array<OneD, NekDouble>(nq, 0.0);
    Vmath::FillWhiteNoise(nq, m_noise, m_Forcing[0], 1, seed);
    for (int i = 1; i < m_NumVariable; ++i)
    {
        m_Forcing[i] = Array<OneD, NekDouble>(nq, 0.0);
        Vmath::FillWhiteNoise(nq, m_noise, m_Forcing[i], 1);
    }
 
    m_index = 0;
}
 
void ForcingNoise::v_Apply(
    [[maybe_unused]] const Array<OneD, MultiRegions::ExpListSharedPtr> &fields,
    [[maybe_unused]] const Array<OneD, Array<OneD, NekDouble>> &inarray,
    Array<OneD, Array<OneD, NekDouble>> &outarray,
    [[maybe_unused]] const NekDouble &time)
{
    // Do not apply forcing if exceeded m_numSteps
    if (m_numSteps && (m_index >= m_numSteps))
    {
        return;
    }
 
    // Update forcing (change seed to avoid getting same result)
    if (m_updateFreq && m_index && !((m_index) % m_updateFreq))
    {
        for (int i = 0; i < m_NumVariable; ++i)
        {
            Vmath::FillWhiteNoise(outarray[i].size(), m_noise, m_Forcing[i], 1);
        }
    }
 
    // Apply forcing
    for (int i = 0; i < m_NumVariable; i++)
    {
        Vmath::Vadd(outarray[i].size(), outarray[i], 1, m_Forcing[i], 1,
                    outarray[i], 1);
    }
 
    ++m_index;
}
 
} // namespace Nektar::SolverUtils