Hi. I’m using COMSOL 5.3 to simulate laminar flow in a microchannel that has few internal closed features inside. I noted that I should use internal boundary to define the non-slip boundary condition for my features. But, I don’t know how to do it. There are “not applicable“ errors shown for these internal boundaries.
Can you please advise?
The correct procedure of doing your geometry is as follow:
1- Drew a rectangle (the main microchannel)
2- Drew the two circles (two obstacles)
3- From the "Geometry", select "Booleans and Partitions", then Select "Difference"
4- From the resulting window, select the rectangle as "objects to add" and select the two circles as "Objects to subtract".
5- If you do the above steps carefully, all boundaries will be active.
Dear Narjes Allahrabbi
For modelling, did you consider the internal walls as a single line or they have thickness? can you show your model here, Then I can help.
Thanks for ypur answer. My model is a long rectangle (as my microchannel) with two circles (as the obstacles against flow) in the channel.
The correct procedure of doing your geometry is as follow:
1- Drew a rectangle (the main microchannel)
2- Drew the two circles (two obstacles)
3- From the "Geometry", select "Booleans and Partitions", then Select "Difference"
4- From the resulting window, select the rectangle as "objects to add" and select the two circles as "Objects to subtract".
5- If you do the above steps carefully, all boundaries will be active.
That is easy, just don't select two circles in fluid flow part. Then their outer boundary will be defined as exterior boundaries automatically. If still need help, send your file to me. I will correct it.
The issue is that I can’t choose any boundary condition for the spheres as they are under “wall” option by default, though “not applicable” is shown for them. Even if I define a new “wall” boundary condition and add the balls, the solution for fluid profile is like when the balls don’t exist.
This means that my model doesn’t include the non-slip boundary condition by the balls.
Dear Sister Narjes,
Please see the attached video. It may help you in specifying the requested boundary conditions.
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