.Buildings.HeatTransfer.Convection.Functions.HeatFlux.rayleigh

Information

This function returns the Rayleigh number. The parameter RaMin is used to transition to a lower limit for the Rayleigh number. This is helpful to avoid a Rayleigh number of zero or to avoid an expression for a convection coefficient that has an infinite derivative near zero, i.e., if h=f(Ra^(1/2)).

Interface

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;

Revisions

May 21, 2015, by Michael Wetter:
Reformulated to reduce use of the division macro in Dymola. This is for issue 417.
July 2, 2013, by Michael Wetter:
Renamed function from raleigh to rayleigh.
August 18 2010, by Michael Wetter:
First implementation.

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