I know this is kinda a star-cd specific question but how would i calculate shear rate (gamma dot) from variables output from a simulation. I dont mean the specifics within the program more a general formula

in star-cd you can use 'operate'command or 'posdat' subroutine. if you want manipulate computational result outside you need write your own program to deal with the output from star-cd. i guess there must be countparts in other cfd package. i am not sure that will help.

cheers, i know about the operate i was going to use that to get around having to use a sub-routine, my question is what do i have to operate to get shear rate, i.e. shear rate =......

as i know for turbulent flow only the layer next to wall shear rate concept makes sense as long as we chose wall function. shear rate = vmag(p) / distance from wal. for laminar flow, general form shear rate should be part of strain tensor that can throughout domain.

yeah im using laminar non-newtonian flow, hence the need for gamma dot