Difference between patches and surfaces in control files

[MarcusAW]

Hi, This should be a simple question, but what is the difference between patches and surface in fwhControl? In the vortexShed tutorial if I would like to only consider the noise generation of just the cylinder patch, it seems like there is no need to define patches when surface is defined.

Any clarification would be appreciated, Marcus

[mkraposhin]

When you use impermeable patches, the analogy reduces to Curle. Indeed, when you solve only for noise generated by flow over a non-moving object, you don't need any additional surfaces except the patch encompassing the body.