Arbitrary Lagrangian-Eulerian#

Lethe contains a small Arbitrary Lagrangian-Eulerian (ALE) module which enables the user to simulate domains which are moving at time and space-dependent velocities. All physics support the ALE module.

subsection ALE
 set enable = false

 subsection velocity
   set Function expression = 0; 0 # In 2D : u;v
   # or
   set Function expression = 0; 0; 0 #In 3D u;v;w
 end

end

  • The enable parameter is set to true if the ALE velocity should be subtracted from the fluid velocity.

The ALE velocity field is specified through the velocity subsection.

  • The Function expression parameter sets the expression for the ALE velocity field in regards to \(u\) and \(v\) for a 2D simulation and to \(u\), \(v\), \(w\) for a 3D simulation.

Warning

The current implementation of the ALE module does not support time-dependent or non divergence-free velocity fields.