Multiphysics#

This subsection defines the multiphysics interface of Lethe and enables the solution of Auxiliary Physics in addition to traditional fluid dynamics simulations.

subsection multiphysics
  set fluid dynamics                  = true

  # Thermal physics
  set heat transfer                   = false
  set viscous dissipation             = false
  set buoyancy force                  = false

  # Tracer
  set tracer                          = false

  # Multiphase flow
  # Volume of Fluid method
  set VOF                             = false
  # Cahn-Hilliard equations
  set cahn hilliard                   = false

end

fluid dynamics: controls if the fluid dynamics are solved. This is true by default and can be turned to false to enable calculation of an auxiliary physic only. When appropriate, this can decrease drastically the computation time.

Tip

fluid dynamics = false and heat transfer = true enables to solve the heat transfer equations with a large time step, with the fluid velocity being defined from the Initial Conditions.

heat transfer: controls if the heat transfer auxiliary physics are solved. This is an advection-diffusion equation.
When set heat transfer = true, these optional parameters can be used:
- viscous dissipation: controls if the viscous dissipation is taken into account in the heat transfer equation.
- buoyancy force: controls if the buoyancy force is taken into account in the Navier-Stokes equations. The buoyancy force is calculated using the Boussinesq approximation.