MIKE 21 BW - Specifying Porosity Layer; 1 DH Boussinesq Wave Module; Recommended Porosity Layer Parameters

Reference Manual
142 MIKE 21 BW - © DHI
1DH Boussinesq wave module
The figure below shows an example where a porosity layer is applied to
model partial reflection in case of a numerical wave flume, see Section 4.3.1.
Figure 5.29 Model setup (vertical cross-section). An 8 point wide porosity layer is
used at the left-hand side boundary
Specifying porosity layer
For a given set of porous flow parameters (see section Recommended poros-
ity layer parameters below), the porosity values required to obtain a desired
reflection coefficient, can be determined by the use of the MIKE 21 Toolbox
program Calculation of Reflection Coefficients.
Important! The porosity should never be smaller than 0.2.
For impermeable structures, the porosity layer should be backed by an
impermeable land grid point.
Recommended porosity layer parameters
When determining the porosities to be used in your simulation, the values of
the porous flow parameters are not that important. Unless you have a specific
reason for using other values, these parameters can usually be left at their
default values, which are:
 Kinematic viscosity: 1.4·10
-6
m
2
/s
 Stone diameter: 0.2 m
 Laminar resistance parameter: 1000
 Turbulent resistance parameter: 2.8