thresholdcapillarypressures.hh

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#ifndef DUMUX_PNM_THRESHOLD_CAPILLARY_PRESSURES_HH
#define DUMUX_PNM_THRESHOLD_CAPILLARY_PRESSURES_HH
 
#include <cmath>
 
#include <dune/common/exceptions.hh>
#include <dumux/porenetwork/common/throatproperties.hh>
 
namespace Dumux::PoreNetwork::ThresholdCapillaryPressures {

template <class Scalar>
Scalar pcSnapoffRegularShape(const Scalar surfaceTension,
                             const Scalar contactAngle,
                             const Scalar inscribedRadius,
                             const Throat::Shape shape) noexcept
{
    using std::cos;
    using std::sin;
 
    const Scalar cornerHalfAngle = Throat::cornerHalfAngles<Scalar>(shape)[0];
 
    // check if snap-off is possible with such contact angle and corner half-angle
    // if the criteriun is not fulfilled, return the lowest negative value to make sure that snap-off will not happen
    if (cornerHalfAngle + contactAngle >= 0.5*M_PI)
        return std::numeric_limits<Scalar>::lowest();
 
    const Scalar cosContactAngle = cos(contactAngle);
    const Scalar sinContactAngle = sin(contactAngle);
 
    // Get tangent of corner half-angle
    const Scalar tanCornerHalfAngle = [&]{ switch (shape){ // optimized tan(corner half-angle) for certain shapes
        case Throat::Shape::equilateralTriangle: return 0.577;
        case Throat::Shape::square: return 1.0;
        default: using std::tan; return tan(cornerHalfAngle);
    }}();
 
    return surfaceTension / inscribedRadius * (cosContactAngle - sinContactAngle * tanCornerHalfAngle);
}
 

template <class Scalar>
Scalar pcSnapoff(const Scalar surfaceTension,
                 const Scalar contactAngle,
                 const Scalar inscribedRadius,
                 const Throat::Shape shape)
{
    if (Throat::isRegularShape(shape)) // call the pc snap-off calculated for regular shapes(same corner angles and side length)
        return pcSnapoffRegularShape(surfaceTension, contactAngle, inscribedRadius, shape);
    else
        DUNE_THROW(Dune::NotImplemented, "Pc snap-off is not implemented for this irregular shape");
}

template<class Scalar>
Scalar pcEntry(const Scalar surfaceTension,
               const Scalar contactAngle,
               const Scalar inscribedRadius,
               const Scalar shapeFactor) noexcept
{
    using std::sin;
    using std::cos;
    using std::sqrt;
 
    const Scalar cosContactAngle = cos(contactAngle);
    const Scalar sinContactAngle = sin(contactAngle);
 
    const Scalar D = M_PI - 3*contactAngle + 3*sinContactAngle*cosContactAngle - (cosContactAngle*cosContactAngle) / (4*shapeFactor);
    const Scalar F = (1 + sqrt(1 + 4*shapeFactor*D / (cosContactAngle*cosContactAngle))) / (1 + 2*sqrt(M_PI*shapeFactor));
    return surfaceTension / inscribedRadius * cosContactAngle * (1 + 2*sqrt(M_PI*shapeFactor)) * F;
}
 
} // namespace Dumux::PoreNetwork::ThresholdCapillaryPressures
 
#endif