calculation of Reynolds number
function ReynoldsNumber extends Modelica.Icons.Function; import MIN = Modelica.Constants.eps; input SI.Area A_cross "Cross sectional area"; input SI.Length perimeter "Wetted perimeter"; input SI.Density rho "Density of fluid"; input SI.DynamicViscosity eta "Dynamic viscosity of fluid"; input SI.MassFlowRate m_flow "Mass flow rate"; output SI.ReynoldsNumber Re "Reynolds number"; output SI.Velocity velocity "Mean velocity"; end ReynoldsNumber;