Materials
By means of a material, you can assign a surface roughness to a model or to specific parts of it. It will affect the surrounding flow field.
To define a new material, open the Insert menu and select New Material. You can also use the shortcut menu of the Materials item in the navigator.
Enter the Name of the material. To consider its specific surface roughness, select the check box in the Surface Roughness Parameters section. You can then define the Sand-grain roughness height Ks (the size of the sand grains) and the Roughness constant Cs. For more information on the surface roughness parameters, see the Chapter 'Advanced'.
You can then assign the material to either a model or to specific parts of the model, the so-called Zones (see the Chapter 'Zones').
Note
For the program to consider the surface roughness, make sure that the corresponding check in the Advanced tab of the Simulation Parameters dialog box is activated (see the Image 'Simulation Parameters').
If you have defined models or zones with different materials, the hierarchy of the surface roughness is as follows: The global roughness defined in the Simulation Parameters dialog box is applied to all objects unless it is overridden by the material properties of each model. The highest priority, though, have the zones with the assigned materials.