Boundary_field_uniform_keps_from_ud.h

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#ifndef Boundary_field_uniform_keps_from_ud_included
#define Boundary_field_uniform_keps_from_ud_included
 
#include <Champ_front_uniforme.h>
 
 
 
/*! @brief classe Boundary_field_uniform_keps_from_ud Classe derivee de Champ_front_uniforme which is for uniform fields
 *
 *      in space and time
 *
 * @sa Champ_front_base Champ_front_uniforme
 */
class Boundary_field_uniform_keps_from_ud : public Champ_front_uniforme
{
  Declare_instanciable(Boundary_field_uniform_keps_from_ud);
};
 
struct pair
{
  double k;
  double eps;
};
 
inline pair k_eps_from_udi(const double u, const double d, const double I, const int dimension)
{
  //Now compute associated K and Eps by appling formula given by :
  //http://en.wikipedia.org/wiki/Turbulence_kinetic_energy
  //http://www.cfd-online.com/Wiki/Turbulence_length_
  //http://support.esi-cfd.com/esi-users/turb_parameters/
 
  //Hypothesis:
  //Cmu=0.09 : k-eps parameter
  //l=0.038 Dh where Dh is the hydraulic diameter
  //Note that Cmu^(3/4)=0.1643
 
 
  //in 3D we have
  //k = 3/2*(u*I)^2
  //in 2D we have
  //k = (u*I)^2
  //with u = initial velocity magnitude
  //eps = Cmu^(3/4) * k^(3/2) * l^(-1)
  //where l is the turbulence length scale which can be expressed as 0.038 Dh
  //Dh is the hydraulic diameter
  double l=0.038*d;
  pair val;
  val.k = ( dimension == 2 ? 1 : 3./2. )*(u*I)*(u*I);
  val.eps = 0.1643*pow(val.k,1.5)/l;
  return val;
}
#endif