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[Nishanth]

What should be the total thickness of Inflation layers for a CFD analysis on fluent?

I'm using the k-omega model to find out the drag of an automobile.

My boundary layer thickness is around 15mm. Should I make sure that inflation covers the whole boundary layer?

[Keyur Kanade]

which model you are using in Fluent? what is application? please check domain extents. 

what results you are expecting? 

also check limits for no. of cells for student version. 

Regards,

Keyur

 

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[Nishanth]

which model you are using in Fluent? what is application? please check domain extents. 

what results you are expecting? 

also check limits for no. of cells for student version. 

I'm using K-omega model to find out the drag of an automobile.

My question is let's say I give inflation with y+ 50 with first layer thickness 0.75mm with growth rate 1.2. What should be the number of layers I need to use?

Should I make sure the inflation covers my whole boundary layer which is of 16mm?

[Rob]

It depends. You want enough mesh to resolve the near wall flow accurately. For aero/auto models they typically look at 10-20 layers for a simple model; but I've seen cases with over 50 layers. Don't forget to resolve the streamwise mesh too. 

[Nishanth]

Hey, thanks for the reply.

Can you please elaborate what you mean by "Don't forget to resolve the streamwise mesh too." Isn't the inflation layer itself a streamwise mesh?

[Karthik Remella]

My colleague here is talking about the mesh resolution in the fluid flow. We generally focus on capturing the BL thickness but it is important to have a good tight mesh in the flow direction. 

I hope this clarifies Rob's comments.