/DT/FVMBAG/Iflag
Engine Keyword Time step for control for Finite Volume Method airbag.
Format
 For Iflag = 0,
1
/DT/FVMBAG/Iflag
$\text{\Delta}{T}_{sca}$ $\text{\Delta}{T}_{\mathrm{min}}$
 For Iflag = 2
/DT/FVMBAG/Iflag
$\text{\Delta}{T}_{sca}$ $\text{\Delta}{T}_{\mathrm{min}}$ Lambda L_type
Monvol_ID
Definition
Field  Contents  SI Unit Example 

Iflag  Finite volume merge flag.


$\text{\Delta}{T}_{sca}$  Scale factor on time
step. Default = 0.9 (Real) 

$\text{\Delta}{T}_{\mathrm{min}}$  Minimum time
step. (Real) 

Lambda  Stability
factor. Default = 0.01 (Real) 

L_type  Time step computation method.


Monvol_ID  Monitored volume
identifier. (Integer) 
Comments
 The $\text{\Delta}{T}_{sca}$ and $\text{\Delta}{T}_{\mathrm{min}}$ 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:$$\text{\Delta}T=\text{\Delta}{T}_{scal}\frac{\text{\Delta}x}{\leftuw\right+c}$$Where,
 $u$
 Gas velocity.
 $w$
 Polyhedron velocity.
 $c$
 Speed of sound.
 $\text{\Delta}x$
 Characteristic length.
The soothing factor is applied using $\text{\Delta}T\leftarrow \mathrm{min}\left(\text{\Delta}T,\text{\Delta}{T}_{old}\left(1+\lambda \right)\right)$ .