valueFraction in partialSlip wall boundary condition
 

Hi everyone;

I am trying to use "partialSlip" boundary on a wall surface which requires the input variable named "valueFraction".

The "valueFraction" is bounded between 0 and 1 with 1 meaning no-Slip and 0 meaning slip. Intermediate value means, we have partial slip boundary condition.

I can see that the governing equation is of form: (1-valueFraction)*___. However, I am not able to fill the blank above.
I came across several posts on this topic but ultimately they were not answered at the end.

I feel the slip length, cell size and valueFraction are related in some way but not sure how.

Can anyone with experience help me in this regard?

Thanks.

Hi,



If anyone find it useful here it is:


where = boundary cell size normal to the wall boundary and is the user specified slip length.


Enjoy!!

Hi, Saideep!

where do you know the expression of valueFraction? Or how could I derive it by myself.

Could you please explain it the issue?

Thanks.

Hi yyq,


I'm not sure but here is what I found about the expression of valueFraction provided by Saideep (see attached PDF). Tell me if it helps :-)

Hi,


Sorry for the late response.

Actually, there is a derivation to end up at this expression.



I remember years ago I found that on CFD online and copied to my notes. But now, my notes are preserved elsewhere and I cant find the thread precisely. I am sure it shall be on the forum.


Hope this helps.

Hi pfavreau,

thanks for your answer, it really helps a lot.

Hi Saideep,

thanks anyway!!

Hello everyone,

Thanks for the discussion. I need to use partialSlip for my simulations. Can any body say if slip length has any relationship with mean free path in Knudsen number?

Thank you