5.8 Wetting And Drying
5.8.2 Description
Wetting and drying refers to the process by which individual cells in the computational mesh transition between wet (active) and dry
(inactive) states during a simulation (see Appendix B.4.7). TUFLOW FV supports wetting and drying by progressively switching on model computations as a function of cell depth. Two depth thresholds, the drying depth, and the wetting depth are set using the
The resultant dry, transitional and wet cell computations are listed as follows and shown in Figure 5.1. The wetting and drying model implementation is summarised in Table 5.12, with a link to the relevant implementation section below. Commands are listed in Table 5.13.
- Dry:
- For cell depths \(<\) the drying depth, the cell is dropped from flux computations. Mass at the cell is conserved. For example, a model with direct rainfall will allow depth to build in the cell however, this mass cannot be transferred to adjacent cells until the depth reaches the transitional depth
- Transitional:
- For depths between the drying and wetting depths (\(\geq\) drying, \(<\) wetting), mass and momentum fluxes are calculated, however cell centre momentum is set to zero. This prevents non-physical velocities in shallow flow depths
- Wet:
- Cells with depths \(\geq\) wetting depth have mass and momentum calculations enabled with no corrections
Figure 5.1: Wetting And Drying Depths
| Model Implementation | Description |
|---|---|
| Wetting And Drying | Sets depth constraints for switching off cell calculations in drying cells. |
| Command | Description |
|---|---|
| Cell Wet/Dry Depth | Optional - Sets the cell wetting and drying depths used to switch off momentum and mass calculations in regions of shallow flow. |
5.8.3 Wetting And Drying
The below shows two examples for wetting and drying thresholds for metric and U.S. Customary units respectively.
Example (metric units).