Choosing the right timestep
 

Hello!

I simulate with sonicFoam a tube with different pressures in it and have problems with the timestep. Sometimes with a chosen timestep, simulation lasts about 1 hour before it fails (and the Courand number is over 1). Is there a way to determine, how large the Courand number will get or is there even a possibility to set the maximum Courand number, so that the timestep will vary?

Yes, there is a possibility to specify a maximum Courant number. See how it's implemented in the interFoam solver (http://www.opencfd.co.uk/openfoam/doc/damBreak.html), or also threads in the forum (e.g. http://www.cfd-online.com/Forums/ope...co-number.html).

Thanks a lot! Like in the post of your link, I also has to add some #include statements into the solver I used (sonicFoam). Now it works great!