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Decreasing the value of y+

How do i decrease the value of y+ for a stirred tank reactor simulation, where the value of y+ is calculated on the surface of coil inserted in it?


OpenFOAM 29-11-20, 5:04 p.m. Harsh235
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You can refine the mesh near the surface of the coil. That should decrease the y+ value.

Regards,
Ashley

30-11-20, 5:17 a.m. ashleymelvin

Yes, Either go with increasing cell numbers or refine mesh using expansion ratio. If you are using snappyHexMesh, go with adding layers to the walls.

Regards,

Divyesh


30-11-20, 5:41 p.m. divyesh

Hey, Thanx Ashley and Divyesh. I tried doing what you both suggested...but after getting a very fine mesh...the minimum average value for y+ i achieved was 59...but i need to take it down below 25...is there something i maybe missing out?

Regards,

Harsh


03-12-20, 5:06 p.m. Harsh235

Hi Harsh,

Since refining did get your y+ value to reduce, I think ypu're on the right path. But since simple refinement would make your simulation computationally expensive, I'd suggest you try changing the expansion ratio, like Divyesh pointed out, to have really small cells attached to the walls (the y+ is dependent only on the size of the cell right next to the walls).

I'd suggest you try the Spoken tutorial on turbulent flow and the additional reading material available in the link below.

https://spoken-tutorial.org/watch/OpenFOAM+version+7/Simulation+a+2D+Turbulent+Flow+in+a+Channel+using+OpenFOAM/English/

Regards,
Ashley


03-12-20, 6:07 p.m. ashleymelvin

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