[Stutti]

Hello CFD-Community,

I am using the Actuator-Disk feature and want it to extract the amount of energy given by the Betz-Limit (and slowing my fluid accordingly).

Following the user-guide (https://www.openfoam.com/documentati...tion-disk.html) I am using the Frouds method, which requires the two parameters (besides disk-area and orientation, which are given by the geometry) Cp and Ct.
For Cp I use 0.59 (what is the Betz-limit) and now I am unsure what to put in for Ct and why I have to set Ct in the first place.
What I am doing right now, following the second equation in the User-Guide Frouds-Method, is Ct = 0,888 what gives me a= 1/3 what, in my understanding, should be the relation between the velocity far before and far behind the actuatordisk, that relates to the Betz-limit.

Is this correct and why do I have to set Ct?

Thank you