We have an exciting announcement about badges coming in May 2025. Until then, we will temporarily stop issuing new badges for course completions and certifications. However, all completions will be recorded and fulfilled after May 2025.
Ansys Products

Ansys Products

Discuss installation & licensing of our Ansys Teaching and Research products.

Transient Thermal-Electric system issue

    • shaoxiang_go
      Subscriber

      Hi, I am trying to run a transient thermal-electric simulation. The idea is to investigate the temperature changes over time when a rectangular voltage pulse is applied to a part of the structure, with the opposite part grounded (Refer to figure). The boundary conditions are set to 300K throughout the whole simulation (Refer to figure). By default, the thermal-electric module is 'steady-state' mode, hence to enable a transient mode simulation, I set the following parameters according to online sources: 

      "antype,4 ! transient
      timint,on"

      What I am expecting to see is a smooth exponential temperature decay over time when the voltage at the falling width of the rectangular pulse hits 0 V (The temperature should still be decaying even when no voltage is administered). However, at 0 V, the temperature immediately returns to 300 K (which is the boundary condition I set - refer to below diagram). This should not be the case? Moreover, when I modified the density or specific heat volume constant, it does not seem to affect the final temperature at all, even though I enable the transient mode. What could be wrong? I am using the ANSYS 2024 version. Thank you very much for your help.

       

    • dlooman
      Ansys Employee

      Those commands should have produced a transient analysis, but it does appear you getting a series of steady state solutions instead.  Did you review the solution output ("Solution Information") for a possible explanation.  I wouldn't recommend using a number like 1e14 for the resistivity of material 3.  It could cause ill-conditioning of the matrices.  A number like 100 should be high enough.

      • shaoxiang_go
        Subscriber

        Hi dlooman,

        Thank you for your suggestion. I have changed the resistivity of material 3 to 100 like what you suggest. However, I am still getting a warning (even before changing the resistivity, sorry that I forgot to mention this earlier) :

        "The coupled field analysis is weakly coupled and requires at least two iterations to achieve a coupled response. Try incrementing the number of iterations." - What does this mean though? I have tried searching this error online but nothing much was mentioned about this error message. Also, which part of the solution output should I look at since it is a document with many pages?. How do I allow the solution to be a transient one instead? Thank you very much.

Viewing 1 reply thread
  • You must be logged in to reply to this topic.