Heat Flow solver failed to converge after 40 iterations, error code 9002



Dear all,

I am trying to simulate a the heat released in a quartz cuvette containing water and air, in which a laser is shined, heating nanoparticles, only if they are in the optical path of the laser beam. As a simple model, I substitute the laser beam in DEVICE with an uniform heat source. The quartz cuvette is surrounded by air.
qubet_modelling_2.ldev (6.1 MB)

When I run the simulation the error code 9002 appears and that the solver failed to converge after 40, 100 or 200 iterations (the values I tried).

What could be the source of this error? I would appreciate any help with this issue, thank you!

Kind regards,


Photothermal heating in all dielectric metamaterials

Hi @g.w.castellanosgonza
Please check these posts. There are posts about “Error 9002”.

Let me know if your problem is solved. If not let’s investigate it further.

Best Regards


Hi @g.w.castellanosgonza, The structure you are trying to simulate is way too large. The HEAT solver can handle simulations having dimension up to a few mm but a 3D simulation of a structure 10 mm x 10 mm x 30 mm would be extremely challenging if not impossible. The reason the solver was able to mesh your structure is because you have used a very coarse mesh. However this coarse mesh is probably forcing the solver to fail as well. You will have to use a minimum mesh size of at least 1 um for the solver to resolve the regions where heat input is varying quickly. For other regions also a mesh size of 10 or 20 um (defined my max edge length) would be preferable. The current settings are just too large in my understanding. Unfortunately if you reduce the mesh settings to the numbers I have mentioned, the solver will require a huge memory to simulate this structure making it quite impossible to run on any machine. I would recommend to try and make the mesh finer (try the min edge length value first), as much as the memory of your computer will allow you to and then run the simulation to see if it converges. Note that you may have to increase the “max refine steps” setting to allow the solver to resolve the mesh completely (How to resolve warning message: “The mesh is valid but may not be adequately refined”).

A couple of other things to note would be that since the heat goes out of your system via convection only, you may have a large temperature in the system. You may need to increase the “max update (K)” limit in the advanced tab of the HEAT solver so that the solver can reach this high temperature within a reasonable number of iteration. Also, you may want to enable radiation in the fluid boundary model as well sine at high temperature radiation might become important as well.


Hi @aalam,

Sorry for the late reply. Thanks for the detailed answer. So DEVICE is better for small volumes in the order of the micrometer and nanometer scale right?

Best regards,



You are right. As I mentioned the maximum size that you should be able to simulate with DEVICE HEAT is may be a couple of millimeters but the solver is best suited for devices with dimension in the range of microns or nanometers.