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Error: The recorded Historical maximum value decreases during simulation?!
Posted 2019年12月31日 GMT-5 19:28 Structural & Acoustics, Studies & Solvers, Equation-Based Modeling Version 5.5 2 Replies
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Dear All:
I followed the approach given in the Blog article, https://www.comsol.com/blogs/using-the-previous-solution-operator-in-transient-modeling, to record the maximum historical value. The following expressions are used,
u-nojac(if(T>u,T,u)); MaxTemp = max(T,u) and a previous soluton node
However, I found the recorded maximum may decrease during the simulation. In my simulation, even a tiny decrease is not allowed. Did anyone also encounter such a issue? How to solve it?
Thanks a lot.
-------------------Yu Zhang
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Hi Yu,
My best guess is that it is a postprocessing artefact. The stored values in each point are probably OK, and what you see is an effect of interpolation or extrapolation.
Regards,
Henrik
Henrik Sönnerlind
COMSOL
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Hi, Henrik,
Thank you for your reply. In my model, the historical maximum value is not allowed to decrease. Could you please provide me a way to achieve that? Should I use the value at the Gauss point?
In addition, when I was trying to use the time derivative of the maximum value, say d(V_max,TIME), in my model, I always got a message:
Failed to find consistent initial values. Last time step is not converged.
Could you please give me some help about that?
Thank you for your help.
Happy new year
-------------------Yu Zhang