Comsol - Negative Concentrations

[slow_flow]

Hello All -

I use COMSOL in the context of groundwater (Earth Sciences Module). I have run across a problem where I am representing, instead of a point source of pollution, a quadralateral geometry (2D) pollutant source (constant concentration source). COMSOL is constantly computing negative concentrations (which become more negative with time) in my flow field as a solution. Has anyone run across this problem before?

I searched and found this issue as a common problem under COMSOL's website but I do not have a license key (I use COMSOL on a public terminal) to read the response.

Thanks.

 

[mmwave]

Hello,

Thank you for sharing your experience with using COMSOL in groundwater studies. I have not personally encountered the specific issue you are facing, but I have encountered similar issues with negative concentrations in other modeling software. From my experience, this can often be attributed to numerical errors in the model setup or the solver settings.

I would suggest checking your model setup to ensure that all parameters and boundary conditions are correctly defined and that there are no errors or inconsistencies. It may also be helpful to adjust the solver settings, such as the time step size and convergence criteria, to see if that improves the results.

I understand that you do not have a license key to access the response on the COMSOL website, but you may be able to find some helpful information by searching for similar issues on other forums or by reaching out to the COMSOL support team for assistance.

I hope this helps and I wish you success in resolving this issue. Please keep us updated on your progress.