|April 16, 2012, 11:29||
Varying time-step and Results freequency
Join Date: Apr 2012
Posts: 2Rep Power: 0
I have a CFX simulation that is basically a pipe with inlet and outlet orifice's. the simulation runs over 4.5ms, with a time step of 0.1ms. I now need to run the same simulation but with inlet events before this to try and replicate initial conditions. This brings the whole simulation to 1050ms (1.05s), but I only need the results from the last 4.5ms as before.
I have it all set up but running it now would give me 10500 time steps and take 600+ hours and 240GB results.
The accuracy of the first 700ms is not so important so ideally I want a time-step of 10ms for the first 700ms, then change to a 0.1ms time-step after this. Is this possible and if so, how?
I would also like to only record the results near the end. I have tried setting trn results to, Time Interval: t>0.99[s], but this gives me a resolves to dimensionless error. Any ideas on this?
|April 17, 2012, 02:00||
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 11,057Rep Power: 86
Why do you use 0.1ms time steps? Have you confirmed these are adequate?
I would run the whole thing using adaptive timesteps, adapting to 3-5 coeff loops per iteration. This means you will be running a sufficiently small time step at all times, and the time step will automatically get bigger when it can and smaller when it needs to.
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