Alternative low gradient damping function

In flat areas with ponded water, the head gradient between grid cells will be zero or nearly zero, which means that as the gradient goes to zero Dt also goes to zero. To allow the simulation to run with longer time steps and dampen any numerical instabilities in areas with low lateral gradients, the cal­culated intercell flows are multiplied by a damping factor when the gradients are close to zero.

Compared to the default damping function, an alternative damping function is available as an Extra Parameter that goes to zero more quickly and is con­sistent with the function used in MIKE FLOOD.

To activate the alternate function, you must specify the following boolean parameter in the Extra Parameters (V1 p. 347) dialogue:.

The alternative function is a single parabolic function. For more detail, see the section Low gradient damping function (V1 p. 467) in the Reference manual.