During the simulation, it is necessary to understand what physics is currently affecting the solution and check the characteristic step for this problem periodically.
If the time step "settles in" (i.e. decreases sharply) in relation to the expected time step, you need to think about whether everything is set and calculated correctly. The simpliest diagnostics is to display "Internal characteristics" in the monitor window, such as:
- Time step;
- Explicit time step (calculated as an explicit convective step).
To make it easier to find the area due to which the step settles in, FlowVision can display quantities both in volume and on a plane.
Is it possible that the time step becomes less than an explicit time step?
Yes, this is possible, since the time step in FlowVision is counted twice per iteration. A time step is calculated on the base of all steps at the beginning of an iteration. After that, the moving body is inserted and the explicit convective step is recalculated. A new time step is not calculated! Therefore, it is quite possible that the new explicit time step will be larger than the time step.
FlowVision team blog
Time step in FlowVision. How to specify - Life hacks
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