CableHydrodynamics.h

#pragma once
 
#include <cmath>
 
namespace cable_hydrodynamics
{
 
constexpr double kLowReynolds = 14.0;
constexpr double kCriticalReynolds = 1e6;
constexpr double kSupercriticalNormalDrag = 0.3;
 
inline double ReynoldsNumber(double speedSquared, double normalSpeed, double diameter, double viscosity)
{
   return speedSquared * diameter / (viscosity * normalSpeed);
}
 
inline double NormalDragCoefficient(double reynolds)
{
   if (reynolds < kLowReynolds)
      return 1.3 + 8.85 / (std::pow(reynolds, 0.85) + 0.01646);
   if (reynolds < 2515.0)
      return 0.75 + 2.35 / (std::pow(reynolds, 0.38) - 1.67);
   if (reynolds < kCriticalReynolds)
      return 1.15 - 5.05 / (std::pow(reynolds, 0.5) - 31.6);
   return kSupercriticalNormalDrag;
}
 
inline double TangentialDragCoefficient(double reynolds)
{
   return 0.015 + 0.7535 / (std::pow(reynolds, 0.9) + 0.1);
}
 
constexpr double kCylinderAddedMassCoefficient = 1.0;
 
inline double InertiaForceFactor(double waterDensity, double volume, double wetFraction, double addedMassCoefficient)
{
   return (1.0 + addedMassCoefficient) * waterDensity * volume * wetFraction;
}
 
inline void MorisonInertiaForce(double factor, const double acceleration[3], const double axis[3], double force[3])
{
   const double axial = acceleration[0] * axis[0] + acceleration[1] * axis[1] + acceleration[2] * axis[2];
   for (int k = 0; k < 3; k++)
      force[k] = factor * (acceleration[k] - axial * axis[k]);
}
 
} // namespace cable_hydrodynamics