protected double constrictionCoefficient(double c1,double c2){
  double rho=c1 + c2;
  if (rho <= 4) {
    return 1.0;
  }
 else {
    return 2.0 / (2.0 - rho - Math.sqrt(Math.pow(rho,2.0) - 4.0 * rho));
  }
}

protected double constrictionCoefficient ( double c1 , double c2 ) { double rho = c1 + c2 ; if ( rho <= 4 ) { return 1.0 ; } else { return 2.0 / ( 2.0 - rho - Math . sqrt ( Math . pow ( rho , 2.0 ) - 4.0 * rho ) ) ; } }
returns the velocity constriction coefficient .
