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-   -   Control of inner iteration (https://www.cfd-online.com/Forums/star-ccm/237096-control-inner-iteration.html)

totosor June 30, 2021 09:39

Control of inner iteration
 
Hello everyone,

I am working on a coupling scheme between neutronic and thermohydraulic using starccm+ v2019.2.

The fact is each physic is solved by an implicit scheme but the coupling between them is explicit so I have to use a very small time step.

A solution consist in doing external iterations that means for a same time step, repeat an iteration but I didn't find anything in starccm+ to do so.

Another solution could be possibly the control of inner iteration, like .getSimulationIterator().step(n) but I don't know if the object exists for a Macro.

If anyone has already seen something like that and can answer me I would be very grateful.

Thomas.

fluid23 June 30, 2021 13:06

It is not clear to me what question you are asking here. Can you clarify?

totosor July 1, 2021 02:58

Hi,

So I'll try to clarify.

I am looking for something to repeat the same time step with the unsteady solver. (like saving all the fields calculated at time t=t_0+dt and go back to time t_0).

One idea I have would be to stop the computation between inner iterations but I don't know if it is possible.

Thx.

FliegenderZirkus July 1, 2021 07:28

Hi, I'm not sure if this helps, but you can run a specified number of iterations, e.g. 3, by writing

sim = getActiveSimulation();
sim.getSimulationIterator().iterate(3, true);


Running three time steps instead could look like this:

sim.getSimulationIterator().run(3, true);


There's also the step() method you mentioned and to be honest I'm not quite sure how that behaves - for a transient simulation and if if you specify number of steps I'd guess it's the same as run()?


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