nikuradse.hh

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// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
//
// SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
// SPDX-License-Identifier: GPL-3.0-or-later
//
#ifndef DUMUX_MATERIAL_FLUIDMATRIX_FRICTIONLAW_NIKURADSE_HH
#define DUMUX_MATERIAL_FLUIDMATRIX_FRICTIONLAW_NIKURADSE_HH
 
#include <algorithm>
#include <cmath>
#include <dune/common/math.hh>
#include "frictionlaw.hh"
 
namespace Dumux {
template <typename VolumeVariables>
class FrictionLawNikuradse : public FrictionLaw<VolumeVariables>
{
    using Scalar = typename VolumeVariables::PrimaryVariables::value_type;
public:
    FrictionLawNikuradse(const Scalar ks, const Scalar roughnessHeight=0.0)
    : ks_(ks), roughnessHeight_(roughnessHeight) {}
 
    Dune::FieldVector<Scalar, 2> bottomShearStress(const VolumeVariables& volVars) const final
    {
        using Dune::power;
        using std::log;
        using std::hypot;
 
        Dune::FieldVector<Scalar, 2> shearStress(0.0);
 
        const Scalar artificialWaterDepth = this->limitRoughH(roughnessHeight_, volVars.waterDepth());
        const Scalar karmanConstant = 0.41; // Karman's constant is dimensionless
        const Scalar dimensionlessFactor = power(karmanConstant, 2)/power(log((12*(volVars.waterDepth() + artificialWaterDepth))/ks_), 2);
        const Scalar uv = hypot(volVars.velocity(0),volVars.velocity(1));
 
        shearStress[0] = dimensionlessFactor * volVars.velocity(0) * uv * volVars.density();
        shearStress[1] = dimensionlessFactor * volVars.velocity(1) * uv * volVars.density();
 
        return shearStress;
    }
 
private:
    Scalar ks_;
    Scalar roughnessHeight_;
};
 
} // end namespace Dumux
 
#endif