Friction velocity in Channel flow

impecca · May 13, 2010, 19:45

Dear Foamers.

I use a pisoFoam based solver and have turbulent inlet boundary(using LES), I hope the turbulence doesn't decay or develop through channel.(like channelFoam)

To normalize the result, I need to know the friction velocity(u_tau or u*).
when I use channelFoam, I can output the dpdx in each time, so from there I could calculate the friction velocity. but pisoFoam case, I have no idea.
So, I am wondering is there any utility to calculate friction velocity.
or equivalent properties. (i.e. u_tau^2 = dp/dx*h = tau_w/rho, where h is half depth of channel)

Thank you very much
Yusik

stainboy · April 10, 2013, 11:09

Hello Yusik,

I'm interested in this as well. Have you found some way to plot u_plus( y+) for channel flow?

Cheers,
Kuba.

CHARLES · April 11, 2014, 02:33

This may be useful to obtain the values you need:
http://www.cfd-online.com/Forums/ope...-testcase.html

May 13, 2010, 19:45	Friction velocity in Channel flow	#1
impecca Member Kim Yusik Join Date: Dec 2009 Posts: 39 Rep Power: 17	Dear Foamers. I use a pisoFoam based solver and have turbulent inlet boundary(using LES), I hope the turbulence doesn't decay or develop through channel.(like channelFoam) To normalize the result, I need to know the friction velocity(u_tau or u). when I use channelFoam, I can output the dpdx in each time, so from there I could calculate the friction velocity. but pisoFoam case, I have no idea. So, I am wondering is there any utility to calculate friction velocity. or equivalent properties. (i.e. u_tau^2 = dp/dxh = tau_w**/rho, where h is half depth of channel) Thank you very much Yusik

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April 10, 2013, 11:09		#2
stainboy New Member Jakub Pola Join Date: Feb 2011 Posts: 22 Rep Power: 15	Hello Yusik, I'm interested in this as well. Have you found some way to plot u_plus( y+) for channel flow? Cheers, Kuba.

April 11, 2014, 02:33		#3
CHARLES Member CHARLES Join Date: May 2013 Posts: 46 Rep Power: 13	This may be useful to obtain the values you need: http://www.cfd-online.com/Forums/ope...-testcase.html