what's the diffirence betwen "run 0" and "run 1" in the end of the file "in.liggghts_run"?

Submitted by fengyi on Tue, 04/25/2017 - 09:52

Hi cfdemers!

I have readed all tutorials file and I find that someone is "run 0" and other is "run 1" in the end of file "in.liggghts_run".
I notice the cfd coupling is specificed by : "fix cfd all couple/cfd couple_every 100 mpi".

so what's the diffirence?

alice's picture

alice | Fri, 04/28/2017 - 12:36

Hello fengyi,
after the coupled solver calls liggghts, the whole file is processed step by step. If the file contains a run 0, no additional time step is calculated at first execution, while for run 1 a single time step is run after the for example 100 time steps that the cfd solver triggers (only at the first coupling step). The better version would be the run 0, but as the run 1 command is only executed once and as the time step size is very small, the impact on the result is absolutely negligible.
Cheers,
Alice

Stephan | Thu, 06/07/2018 - 14:35

Hi,

I would like to ask a little more detailed before digging too much in the source: the actual run-command at the end of the in-file is therefore not necessary because the fix couple/cfd command takes care that the necessary number of liggghts timestep are calculated?! Therefore the number given in the in-file behind "couple_every" has to be identical to the one given in the couplingProperties-file behind the "couplingInterval" key word?!

Best Regards
Stephan