This scheme is only used with the ALE formulation (Arbitrary Lagrangian Eulerian) and in the CFD
version of
Radioss. The force is calculated using the
relation:
(1)
Where,
-
- Grid velocity
-
- Material velocity
-
- Element volume
-
- Upwind coefficient (user-defined, default = 1 for full upwind)
When a Lagrangian formulation is used, the values of
and
are
equal. Thus, Equation 1 is equal
to zero.
Upwinding Technique
An upwinding technique is introduced to add numerical diffusion to the scheme; otherwise it is
generally under diffusive and thus unstable. The upwind coefficient used in
Equation 1 is
calculated by:
(2)
Development of a less diffusive flux calculation is currently under
investigation.
(3)
This option is activated with the flag INTEG (only in the CFD version).