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Raja March 10, 2008 06:29

Flow resistance model
Dear Friends,

I am to model the radiator as volume flow reistance (using Isotropic loos model). For that I will have to get Linear and Quadtratic resistance co efficients. Kindly can anyone explain how these two coefficients are obtained in measurements and how to get these values to CFX simulations.

Thanks a lot for your valuable time and help.

Thanks and regards

Dr Flow Squad March 10, 2008 08:54

Re: Flow resistance model
Quadratic Resistance:

Kq = dP/dx * 1/U^2

which equals Kq = 1/dx**rho*zeta where zeta is the pressure drop coefficient : zeta = dP / Pdyn.

Similar the linear constant is determined by: Kl = dP/dx * 1/U

Raja March 10, 2008 09:57

Re: Flow resistance model
Thanks a lot for the explanation. I have Airflow (m3/s) and Pressure loss curve. From that how to derive these co efficients?

Raja March 10, 2008 13:07

Re: Flow resistance model

Could anyone explain about determinig the Permeability of radiator? Inorder to find linear resistance co efficeient, I am in need of gettting radiator permeability details?

Thanks in advance.

wake March 11, 2008 03:02

Re: Flow resistance model
I think no need for permiability. convert the m3/s to m/s second by using the flow area (may be ur radiato area). Fit a curve (trend line)with only quadratic and linear terms in excel. use intercept at zero for avoiding constant term. supply this quadratic and linear terms to cfx...

hope this will help

Raja March 11, 2008 03:24

Re: Flow resistance model
Thanks a lot Mr. Wake. I will try in that way.

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