Learning Forum

[pvat5077]

Dear All,

I am trying to model Dean vorticities in a spiral microchannel with the initial diameter of 7mm, the width of 300um and the height of 40um. The velocity at the inlet is 0.9m/s. Considering water as the working fluid, my Re number is 63.3 and De number is 4.5.

The B.C.s are velocity inlet and pressure outlet and no-slip on the walls.

I use SIMPLE algorithm with default settings, and my solution perfectly converges till 1e-6; however, I cannot get the vorticity in a plane perpendecular to the flow. I was wondering what is the problem. 

Any advice is highly appreciated.

Kind regards,

[SRP]

Hi,

Make sure you're choosing the correct plane for visualization. In a spiral microchannel, vortices are typically generated in a plane perpendicular to the flow direction. Ensure that you are examining the vorticity in the correct cross-sectional plane.

Thank you.

[pvat5077]

Dear support team member,

Thanks for your prompt response. 

The plane in which I choose to depict the velocity vectors is most probably perpendicular to the main flow direction. Is there any specific way embedded in the software to create planes perpendicular to the main flow direction that I am not aware of?

(In the meantime, I have increased the number of grids, changed the solver from SIMPLE to Coupled, changed the descritization of momentum from second order to MUCSL, and done lots of other things, but I am still not capable of capturing vorticity. Also, I am sure that there should be a vorticity since, while maintaining the cross-section and velocity, and also settings and mesh, I have simulated a 3/4-circle microchannel and I have obtained powerful vorticities!)
I appreciate your time and response. If the problem is solved with your suggestion, I'll inform you that the issue has been resolved. If not, I'll write a detailed overview of my mesh and settings for other Fluent users.

Sincerely yours,

Parham