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 NIK September 20, 2007 07:43

Difference between laminar and turbulent separatio

What is the difference between laminar (LS) and turbulent separation (TS) for a flow over circular cylinder?

 gocarts September 20, 2007 09:00

Re: Difference between laminar and turbulent separ

If it's any help try Dimples on Golf Balls for an explanation of laminar and turbulent boundary layer separation over a sphere - I think you'll find the reasoning similar to the flow over a cylinder.

 Gerrit Groot September 20, 2007 12:50

Re: Difference between laminar and turbulent separ

What difference do you want to know about?

The turbulent one will have a smaller wake, this is why skaters use strips on their arms (streamlined shapes like cycling helmets are not allowed for them).

 NIK September 21, 2007 05:06

Re: Difference between laminar and turbulent separ

Thanks. In one paper by Trevin et. al, he talks about LS (laminar separation) and TS (turbulent separation) at Re=140000. How can we get laminar or turbulent separation using the same code?

 Gerrit Groot September 21, 2007 05:25

Re: Difference between laminar and turbulent separ

First of all, I suppose your code is 2D.

Does it have a transition model?

 NIK September 21, 2007 07:28

Re: Difference between laminar and turbulent separ

My code is 3D DES using S-A turbulence model.

 Gerrit Groot September 21, 2007 07:41

Re: Difference between laminar and turbulent separ

Ooh, isn't that a bit heavy for cylinder flow? Why don't you use a 2D solver? You run in fully turbulent then I suppose?

Anyway, if you only want to see the difference in the wake for engineering purposes, I think it's tabulated somewhere, maybe in the drag book by Hoerner.

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