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Time Domain: Results mismatch when adding additional range
Posted 27 mag 2025, 08:51 GMT-4 Mesh, Results & Visualization 3 Replies
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Dear Network,
I have a simple time transient thermal analysis (only heat conduction) that runs well. However when adding an additional range I observe that the results before that range (temporarily wise) are changing what is very strange.
In a nutshell : I have results A untill 10ms achieved using rangeA
I run a new simulation with an additional range called rangeB.
So my full simulation time step for that new simulation is rangeA and rangeB like rangeA = 0,0,1,0,001 and then rangeB = 0,001, 1, 10 (this is an example not real values)
Values (especially peak values) with the new simulation are strongly different compared to the initial values from the first simulation. I tried user controlled mesh and a lot of things but nothing change. Do you have any advice ?
Maybe the fact that resolution in rangeA is quite different than resolution=timestep in rangeB ?
Many thanks
Guillaume
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Usually when a transient calculation is set up Comsol defaults to free time stepping. This often leads to very different results when calculating over different time spans.
Try using fixed time steps, with the time step chosen based on your physical intuition about the problem.
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Note that the default initial time step used for the free time stepping is a certain fraction of the total interval. So it may suffice to just set the initial step manually and keep the free time stepping.
-------------------Henrik Sönnerlind
COMSOL
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Thanks! I’ll try adjusting timesteps for smoother transitions.