Discussion Forum

Hello Theodore,
Depending on which licenses are included in your license, you may have access to a physics interface called "Free and Porous Media Flow" (see screenshot), which would make coupling of the (free) flow in the cannula to the flow in the (porous) adipose tissue much easier than doing it "by hand". If you do have access to that physics interface, you will find various tutorials for it in the Applications Libraries (under the File menu in the software) and Application Gallery (on the COMSOL website).
Best regards,
Jeff

Jeff,

I have looked over the free and porous media flow model, and this provided some insight. However, for my simulation, we are only interested in determine the time it takes for the insulin to flow from the cannula (inserted in the adipose) to the 'bottom' of adipose tissue, where a blood vessel might be perhaps.

It sounds like I misunderstood what you were trying to accomplished, but then what is the second physics you are trying to couple to? I am getting the impression that there's only one physics (porous media flow) involved, if I understand you correctly.
Perhaps you can provide a sketch of the geometry along with the equations (including BCs) that you would like to solve. It can be easier for Discussion Forum users (myself included) to productively chime in if the problem is posed in a very specific, mathematical way, rather than in words.
Jeff

Jeff,

I have attached the .mph file for my COMSOL project.

The simple schematic is meant to represent a cannula inserted into a porous adipose tissue region. As of now I have 3 physics, laminar flow to represent the insulin being pumped through the needle, and then Darcy's law + transport of diluted species to evaluate the concentration of insulin at any point.

The goal of my simulation is to calculate the concentration of species c (insulin) at the bottom of the geometry (where a theoretically capillary bed would lie).

Right now, our concentration is reading to be in the order of 10^-17 at the very bottom. It is evident that the ~6 molar insulin is not being transported efficiently through the porous matrix. Do you have any idea why?

Thank you. Any help is appreciated.

The file size (600mb) was too large too attach. I will upload screenshots of my model builder soon.

Hello Theodore,
You can use the "Delete all meshes" and "delete all solutions" buttons on the mesh and study ribbons to minimize file size before sending.
Jeff

Jeff,

Sorry for the late response. I could not find the 'delete all solutions' option, so I deleted the study which had a surface 2d plot for velocity in the needle and adipose region, as well as a line average for the concentration of insulin at the bottom of the geometry (the model for the beginning of the capillary bed.

Jeff,

I found the delete all meshes and delete all solutions options and have attached our most recently updated file. Please get back to me as soon as you can with advice as to how we can fix our issue.

It seems that no matter what we change our parameters too, the line average values for concentration do not seem to change, and are in the order of 10^-17... clearly very low.

Thank you very much!!

-Theodore

Jeff,

Again, see most recent update.