Hints & Tips
When the depth of a fluid is small compared to its lateral extent, it is often a good approximation to assume the flow properties are independent of depth and treat the flow as two dimensional rather than three dimensional. Examples involving shallow flows are painting, floods, estuary circulation, and liquid coatings. In FLOW-3D these types of flows are best treated using the “shallow-water” or “depth-averaged” model option, iswat=1.
With this option, all flow is restricted to a single layer of grid elements in the z direction. This greatly reduces the computational resources needed to obtain solutions. Ground topography can be defined within this layer using the FAVOR™ method; and fluid surfaces, tracked with the VOF method, allow for the treatment of surface waves or other variations in fluid depth. Coriolis forces, surface tension, heat transfer, surface evaporation, and most other physical models in FLOW-3D can be used in connection with the shallow-water model.