I have problem

a) Is it possible to make automatic excaution of UDF function "execute_on_demand" at each time step of unsteady calculation.

b)In a unsteady calculation how to fix the number of iterations in Fluent manual it says that 10-20 is good but I am getting solution converged even if I use 100.

3)How to write certain value calculated during each time step to a txt file.

Q

Hello!

Maybe some of this could help:

a) I think you can use EXECUTE_AT_END instead. Such a UDF would be executed at the end of each time step.

b) You should make sure that each time step converges. If you need too many time steps, try one of the following: (i) start from a converged or nearly-converged steady state solution if possible, (ii) reduce the time step size, (iii) check your model - is it correct?, (iv) perhaps change grid size or URF/CFL?.

c) a UDF could do this via EXECUTE_AT_END. you could also print it to the console window along with the residuals, it's in a menu somewhere (doesn't remember right now). if you are not taking many timesteps you can also save the case and/or data files for each timestep using file->write->autosave for post-processing. It depends on what you want to save it for, I guess.

/Henrik