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Old   May 19, 2013, 07:57
Default turbulent flow around cylinder
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kazem
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I have been studing external flow around a cylinder at Re=10e6 ,Ihave been using k-e model. pressure coefficient (that attach below) is incorrect !
because pressure coefficient is larger than one.
my problem is putting pressure on the referrence values??
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Old   May 29, 2013, 06:06
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Rami Ben-Zvi
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Hi kazem azizem,

AFAIK, the drag force is Fd = 1/2 * Rho * U^2 * Cd. Therefore, if you normalize everything consistently, (e.g., density, velocity and pressure by rho0, U0 and 1/2 * rho0 * U0^2, respectively), you should be OK.

Am I missing something?

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Old   May 29, 2013, 16:59
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Quote:
Originally Posted by Rami View Post
Hi kazem azizem,

AFAIK, the drag force is Fd = 1/2 * Rho * U^2 * Cd. Therefore, if you normalize everything consistently, (e.g., density, velocity and pressure by rho0, U0 and 1/2 * rho0 * U0^2, respectively), you should be OK.

Am I missing something?

Rami
hi Rami azizam
what do you mean normalize velocity or density consistly?
Did you mean dimensionless expressions of velocity and pressure ...?
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Old   May 30, 2013, 13:05
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Rami Ben-Zvi
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Kazem Jun,

Yes, that is what I mean. After all, Cd is mearly a nondimensional form of the drag force, Fd. I am not sure though if the form I had used (Fd = 1/2 * Rho * U^2 * Cd, in which case you get Cd=2 for an infinite plate normal to the flow) is the conventional or is it without the 1/2.

Khoda hafes,
Rami

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