.TRANSFORM.Utilities.CharacteristicNumbers.GrashofNumber

Information

Often takes a role in natural convection prcoesses that Reynolds number does in forced convection.

Defined to be the ratio of the buoyancy forces to the viscous forces acting on the fluid.

• Ja = cp*(Ts-Tsat)/h_fg

If Gr/Re^2 ~= 1 then free and forced convection must be considered.

If Gr/Re^2 << 1 then free convection effects may be neglected.

If Gr/Re^2 >> 1 then forced convection effects may be neglected.

Interface

function GrashofNumber
  extends Modelica.Icons.Function;
  input SI.Length x "Position for local Gr_x or characteristic surface length Gr_L";
  input SI.PrandtlNumber Pr "Prandtl number";
  input SI.Temperature T_wall "Wall temperature";
  input SI.SpecificHeatCapacity cp "Specific heat capacity";
  input SI.Temperature Ts "Surface temperature";
  input SI.Temperature Tsat "Saturation temperature";
  input SI.SpecificEnthalpy h_fg "Latent heat of vaporization";
  output Units.NonDim Ja "Jakob number";
end GrashofNumber;