4.9.9. Buoyancy Model

The Buoyancy Model Specification block in solution options is where you define which buoyancy model you want to use.

Begin Solution Options

  Begin Buoyancy Model Specification my_buoy
    Buoyancy Model = Differential
  End

Details about the Buoyancy models can be found in Conservation of Momentum. The available options for the buoyancy model are:

NO_BUOYANCY

$\int_V \rho g dV = 0$

BUOYANT

$\int_V \rho g dV = \rho g V$

DIFFERENTIAL

$\int_V \rho g dV = g V (\rho - \rho_\circ)$

BOUSSINESQ

$\int_V \rho g dV = \frac{\rho_\circ g V}{T_\circ} (T_\circ - T)$

If you use the differential or Boussinesq model you also need to provide reference properties used to calculate $\rho_\circ$ (and/or $T_\circ$ ).

Begin Solution Options

  Begin Buoyancy Model Specification my_buoy
    Buoyancy Model = Boussinesq
    Buoyancy Reference Temperature = 300
  End

Begin Solution Options

  Begin Buoyancy Model Specification my_buoy
    Buoyancy Model = Differential
    Buoyancy Reference Temperature = 300
    Buoyancy Reference Mass_Fraction O2 = 0.2
    Buoyancy Reference Mass_Fraction N2 = 0.8
    Buoyancy Reference Mass_Fraction He = 0.0
  End