function rayleigh
extends Modelica.Icons.Function;
input Modelica.Units.SI.Length x "Layer thickness";
input Modelica.Units.SI.Density rho "Mass density";
input Modelica.Units.SI.SpecificHeatCapacity c_p "Specific heat capacity";
input Modelica.Units.SI.DynamicViscosity mu "Dynamic viscosity";
input Modelica.Units.SI.ThermalConductivity k "Thermal conductivity";
input Modelica.Units.SI.Temperature T_a "Temperature of surface a";
input Modelica.Units.SI.Temperature T_b "Temperature of surface b";
input Real Ra_min "Minimum value for Rayleigh number";
output Real Ra "Rayleigh number";
end rayleigh;