creating a flow in a PDMS channel

Fatemehsadat Mirghaderi

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I'm trying to create a channel in COMSOL with fluid flow in it. I believe I am using correct feature of COMSOL. The version I'm using is 5.6. I took the following steps from beginning:

1- Model Wizard 2- 3D 3- Fluid Solid Interaction physics which contains: (laminar flow (spf) , solid mechanics (solid), fluid-structure interaction (fsi1), deforming domain). and deformation geometry physics are chosen 4- stationary

5- Using geometry to create two blocks with following dimensions: 5-1- Block 1: (width = 300 , depth = 2000, height = 300) 5-2- Block 2: (width = 100 , depth = 2000, height = 100) (position: corner, x=100, y =0, z=10) Block two is in Block one a screenshot is attached for your reference (image1).

6- Materials: H2O liquid and PDMS. PDMS is for outer block (bigger block which is the channel) and H2O for the inner/smaller block which is the flow.

7- Deforming domain is the bigger block.

8- Fluid flow is 2E-6 in x-direction and pressure is 2E6. Question: how can I choose input and output?

I have one warning, which I don't know how to fix: There is no feature constraining the pressure. A pressure constraint is required to specify the pressure level. Ignore this warning if the pressure is constrained using pointwise or weak constraints. - Node: Laminar Flow (spf)

Also, I will need to fix the PDMS channel cross-section wall in a way that it doensn't move backward or forward. With having all the above items implemented, I get the following error:

  • Feature: Stationary Solver 1 (sol1/s1) Failed to find a solution. Maximum number of segregated iterations reached. Returned solution is not converged. Not all parameter steps returned

Could you please guide me by introducing a tutorial or guidance on how to make a channel with flow inside to look how the fluid flow deforms the channel?

thank you and best regards, Fatemehsadat Mirghaderi


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