Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Error: The recorded Historical maximum value decreases during simulation?!

Please login with a confirmed email address before reporting spam

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

2 Replies Last Post Jan 1, 2020, 5:20 p.m. EST
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 5 years ago Jan 1, 2020, 3:33 p.m. EST

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
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

Please login with a confirmed email address before reporting spam

Posted: 5 years ago Jan 1, 2020, 5:20 p.m. EST
Updated: 5 years ago Jan 2, 2020, 3:04 p.m. EST

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
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

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.