/DT/FVMBAG/Iflag
Engine Keyword Time step for control for Finite Volume Method airbag.
Format
- For Iflag = 0,
1
/DT/FVMBAG/Iflag
ΔTsca ΔTmin
- For Iflag = 2
/DT/FVMBAG/Iflag
ΔTsca ΔTmin Lambda L_type
Monvol_ID
Definition
Field | Contents | SI Unit Example |
---|---|---|
Iflag | Finite volume merge flag.
|
|
ΔTsca | Scale factor on time
step. Default = 0.9 (Real) |
|
ΔTmin | Minimum time
step. (Real) |
[s] |
Lambda | Stability
factor. Default = 0.01 (Real) |
|
L_type | Time step computation method.
|
|
Monvol_ID | Monitored volume
identifier. (Integer) |
Comments
- The ΔTsca and ΔTmin can be defined to ensure stability and a minimum time step size by triggering additional finite volume merges when the FVMBAG entity penalizes the computation.
- When using
/DT/FVMBAG/2, time step is computed as:ΔT=ΔTscalΔx|u−w|+cWhere,
- u
- Gas velocity.
- w
- Polyhedron velocity.
- c
- Speed of sound.
- Δx
- Characteristic length.
The soothing factor is applied using ΔT←min(ΔT,ΔTold(1+λ)) .