Reference / Input deck / model / boundary conditions / wall / roughness
roughness
Surface roughness; unset, the wall is smooth.
typerequired
required
Which roughness measure the value gives.
Options
| Value | What it does |
|---|---|
| height | The value is the equivalent sand-grain height of the roughness elements. |
| length | The value is the aerodynamic roughness length, converted internally to a sand-grain height of length / 0.03. |
Used inaskervein
Guidance: Choosing a wall model →scalar
float·not set by default·>= 0 m·give either 'scalar' or 'field'
Uniform roughness over the wall, as the measure 'type' names.
Used inaskervein
field
str·not set by default
VTP file with a point array named 'Roughness'; each wall face takes the nearest point's value.
Used inbolund
thermal modeladvanced
default owen thomson·'thermal model' only applies when kind is 'wall function' and either temperature is set or heat flux is set
How roughness affects wall heat transfer under the compressible wall function.
Options
| Value | What it does |
|---|---|
| owen thomson default | Adds a thermal sublayer resistance between the surface and the roughness crest, so the Stanton number rises less than the skin friction. |
| reynolds analogy | Omits that resistance, so the Stanton number rises in proportion to the skin friction. |