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Hello Sayee Srikarah Volaity

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Hi, Sayee

I´m currently working on a simulation of a channel with laminarflow over a well with a hydrogel. Using laminar flow physics an brinkmann for the hydrogel and having a similar issue regarding die boundary between those. I m able to simulate something, but not it wont take the hydrogel correctly. Did u find a solution jet ?

Best regards, Martin

If you are employing different physics in two different but adjoining domains, then it seems to me that you need to tell the model how you want these two domains to be related. I usually do other kinds of physics problems than your example, but analogous situations arise in my work. Anyway, I think you need to set up a "multiphysics" configuration. You need to ensure that the boundary condition, between the domains, that is enforced on the flow-like variable (sorry that I don't know what it is called, in your model) when solving the physics in at least one of those two domains, is assigned to be equal to (or otherwise related to) whatever is the corresponding variable for that quantity from the other domain. You need to decide if this should be a self-consistent calculation (where both domains have their physics solved, while interacting with each other) or simply one where you solve the physics in one domain and then use it to determine a flow (or whatever) boundary condition into the other domain, which is then also solved separately.

Anyway, if: (1) you post your .mph model to the forum, and (2) you explain the exact nature of the physical coupling between these two domains that you are trying to realize, then you may just receive some useful advice from other folks here. Comsol is a math and physics code. When you set up different physics (not merely different material properties) in different domains, it is typically impossible for the code (that is, the people who wrote it) to guess how you want to couple those systems. So you need to specify the right physics/relationships at the boundary, whether you want them calculated self consistently or first one then the other, etc. There can be a number of subtleties to doing this. If what you want to do is a common example that the Comsol folks have already studied and documented, you might find ready-to-go examples in the Application Library or elsewhere. If not, then you need to understand more about the details of your particular multiphysics problem.

For general guidance on setting up such coupled multiphysics problems, see: https://www.comsol.com/support/learning-center/article/25501/122

Finally, if you succeed, and if you think this is a worthy/important problem that others may also want to solve, then I encourage you to post your solved example to the Application Exchange: https://www.comsol.com/community/exchange/ .