Number of division of boundary layer

[KABEL]

Hello everyone,

I've been spending days trying to solve this issue.
How to retrieve the number of division of boundary layer using the Y+ methodology ?

Any hint is really appreciated!
Thanks
_______
Regards,

 

[SwinnyGG]

Are you asking about first cell size?

What exactly are you asking?

 

[KABEL]

Hi, thank you for your quick response,I really appreciate it;

I'm asking about the division numbers of the first cell size,

Thank you in advance,
Sincerely,

 

[Sparweb]

KABEL,
You haven't mentioned the software you are using, what is being modeled, what kind of model boundary conditions were applied, so there's really no way to guess.


No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[KABEL]

Hi ,
SparWeb, thank you for your response,
For the software I'm using is ANSYS FLUENT, I model the flow of air around a wing profile, and for the boundary conditions : the angle of incidence is 15 °,and the speed standard is 55 m / s. I used the K-w model.
if you need additional information please let me know,

Thank you in advance,
Sincerely,

 

[rb1957]

do the tutorials suggest something ?

how about trying different values, looking for convergence ?

another day in paradise, or is paradise one day closer ?

 

[KABEL]

Hi,
rb1957,
I'm interested in what happening on the wall, so I want to know how often do I divide the thickness boundary layer sigma ?
sigma= 0.0002m
regards,

 

[rb1957]

ok, but you know you're approximating the boundary layer by splitting it into these layers. So it makes sense that you could try several numbers (2, 3, 4, ...) and see if/when you get convergence. It also makes sense (to me) that there are tutorials for this type on analysis and that they may suggest something.

another day in paradise, or is paradise one day closer ?

 

[KABEL]

rb1957 , thank you very much for your time and your responses , I really appreciate it
I've tried those things,and now I'm looking for a method that can give that in the first try

 

[SwinnyGG]

I've tried those things,and now I'm looking for a method that can give that in the first try

Well... that's not how building a CFD model works. There's no free lunch.

 

[rb1957]

if you've tried them then you have a good idea of what works. You "should" do a mesh refinement to ensure your flow field has converged properly, unless you have enough experience to believe your CFD results are sufficiently accurate.

another day in paradise, or is paradise one day closer ?

 

[Sparweb]

Hi Kabel,
I am still trying to decipher what you want to do.

Since I had an occasion to look at a CFD sim I was working on earlier this year, I took a screen-capture for an illustration.
This was using SimScale, and I have ho insight related to FLUENT to offer you. But all CFD has some elements in common. This simulation also uses K-omega, like yours.
Below you can see the divisions, and the subdivisions, of the mesh, and the boundary intersections.
In this case, you can see the scale bar at the bottom, and estimate that the minimum mesh size is 6mm near the boundary, and coarsens to 12 and 24 farther away.
If I wanted to refine or coarsen this mesh in SimScale, I only need to change a couple of parameters in the mesh configuration, re-mesh, and re-run the sim.
You've mentioned that your mesh is refined to 0.2mm. We don't know the size of the wing you are simulating, so there's no way to tell if this is appropriate or not.
Now that I've laid the ground work of the subject being discussed, can you ask your question, using these terms of reference?
Have you adjusted your mesh to test its convergence, as RB1957 recommended?

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF