It is a requirement for CMUT models to be considered as large deformation. To incorporate this into the OnScale Grid, principally the geom command is used.
In order to do this correctly, some simple rules apply:
- Large deformation regions must always be a skewed grid
- A skewed grid can be both small and large deformation
- CMUT models can typically be a mix of large and small deformation (small deformation for purely wave-propagation aspects)
- Electric window that defines the Electrostatic solution must be wholly in the skewed region
There are some trade-offs that must be made in order to compensate for the more intensive computational requirements of these models.
- Electric window matrix is recalculated every timestep due to deformations
- Significantly more 'costly' than piezoelectric window (due to the geometry updates required)
- Therefore always try to minimise the electric window for speed
- Overall, a standard partition grid can be ~ x5 faster than a skewed partition. It is important to bear this in mind when running CMUT models.