# Control of inner iteration

 Register Blogs Members List Search Today's Posts Mark Forums Read

 June 30, 2021, 09:39 Control of inner iteration #1 New Member   Thomas Join Date: Jun 2021 Posts: 2 Rep Power: 0 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.

 June 30, 2021, 13:06 #2 Senior Member   Matt Join Date: Aug 2014 Posts: 947 Rep Power: 17 It is not clear to me what question you are asking here. Can you clarify?

 July 1, 2021, 02:58 #3 New Member   Thomas Join Date: Jun 2021 Posts: 2 Rep Power: 0 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.

 July 1, 2021, 07:28 #4 Member   Join Date: Nov 2019 Posts: 93 Rep Power: 6 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()?

 Tags coupling, inner iteration, macro