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Topology Optimization: Comsol 6.3 vs Comsol 5.6 solution issue

Posted 03.06.2025, 06:50 GMT-4 Electromagnetics, Heat Transfer, Optimization Version 6.3 1 Reply

Ashok Vemparala
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Hi Everyone, I am working on a Topology Optimization setup of model (that consists of two materials) that undergoes Induction Heating(Physics involved: electromagnetic heating) in two step study ( Step1: Coil Geometry analysis, Step2: Frequency-Transient Solver, the optimization is applied for step 2). At first, I was having trouble running the above topology optimization in COMSOL 5.6 as I would repeatedly get "Warning: Forward solution failed, requesting reduced step." message and I was able to solve the issue by upgrading to COMSOL 6.3 But now I am facing a new problem, I am trying to run the same study in stationary solver instead of transient solver and I am not able to perform the optimization in COMSOL 6.3 as it keeps giving me an error. I don't face this issue when I run the same study in COMSOL 5.6, so I have been trying to modify the solver config to replicate the solver configs of COMSOL 5.6 but I keep getting the error.

I would really grateful any help to solve this and please let me know if you need any further information regarding this.

Best, Ashok

P.S. Please go through this link for more context on previous issue.

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1 Reply Last Post 03.06.2025, 07:50 GMT-4
Kristian Ejlebjærg Jensen COMSOL Employee

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Posted: 6 months ago 03.06.2025, 07:50 GMT-4
Updated: 6 months ago 03.06.2025, 08:34 GMT-4

Hi Ashok

The solver configuration should be preserved when opening a 5.6 model in 6.3, but we often recommend regenerating the solver sequence.

You can attempt to fix the problem by

  • switching to manual scaling of dependent variables

  • going for a different nonlinear method

  • increasing the nonlinear iteration count,

  • or switching to a Fully Coupled as you seem to be using a Segregated solver.

  • plotting the various physical variables and their extreme values during the nonlinear solver, i.e. if you set a filter length smaller than the local mesh size in the Density Model feature, you can get negative filtered values which give rise to unphysical material properties that make the model unstable.

Best regards,

Kristian E. Jensen

Technical Product Manager, Optimization

Hi Ashok The solver configuration should be preserved when opening a 5.6 model in 6.3, but we often recommend regenerating the solver sequence. You can attempt to fix the problem by * switching to manual scaling of dependent variables * going for a different nonlinear method * increasing the nonlinear iteration count, * or switching to a Fully Coupled as you seem to be using a Segregated solver. * plotting the various physical variables and their extreme values during the nonlinear solver, i.e. if you set a filter length smaller than the local mesh size in the Density Model feature, you can get negative filtered values which give rise to unphysical material properties that make the model unstable. Best regards, Kristian E. Jensen Technical Product Manager, Optimization

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