GASDYN_UpwindOffset
(chamberwise) GASDYN parameter for FPM1
Default:
GASDYN_UpwindOffset = 0.15
It represents the parameter \( \alpha\) in
GeneralizedUpwind.
Additional information:
The spatial shift in order to compute the upwind quantities is
GASDYN_UpwindOffset times smoothing length. i.e.
\begin{align} \mathbf{v}_{uw} = \mathbf{v} - \frac{1}{2\rho c} \left( p^+ - p^- \right) = \mathbf{v} - \frac{1}{2\rho c} \left( p(\mathbf{x}+\gamma h \mathbf{n}_{uw}) - p(\mathbf{x}-\gamma h \mathbf{n}_{uw})\right)\end{align}
where \( \gamma\) represents the present parameter
GASDYN_UpwindOffset and \( \mathbf{n}_{uw}\) is the upwind direction.
GASDYN_UpwindOffset is equal to the parameter \( \alpha_{uw}\) in equation (13) in the FPM1-paper
paper_SIA_2005_kuhnert.pdf.
Refer also to equations (6.12) and (6.13) in
thesis_kuhnert.pdf. Here,
GASDYN_UpwindOffset represents the value \( \Delta \tau \frac{c}{h}\).
Note: This parameter can also be set chamberwise for multiphase simulations (see also
KindOfProblem,
CHAMBER).
If it is not set for specific chambers, it is automatically set according to the non-chamberwise definition for all chambers.