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-   -   Estimating pressure drop from the shear stresses (http://www.cfd-online.com/Forums/fluent/45510-estimating-pressure-drop-shear-stresses.html)

K.Baker July 25, 2007 12:11

Estimating pressure drop from the shear stresses
 
Hi to all : I have a two phase pipe flow I predicted the shear stresses at the wall and at the interface by using report surface integrals but now i need to estimate the pressure drop from these values and i have no idea to how can I did this ? Is there any relation between the pressure drop and the shear stresses can i predict by it the pressure drop?

Thanks to any suggestions K.Baker


beginner July 25, 2007 15:16

Re: Estimating pressure drop from the shear stress
 
i am very interested in your question what do you mean with surface integral,which model do you use (mixture...).

I am looking for somebody capable to explain me the link between the BLASIUS Law for friction in homogeneous two phase flow in pipe and the drag coeficient which is proposed in fluent. Is it possible to get some data with fluent???

Sorry i am just a beginner, hoping that my question will interested you.

bye

K.Baker July 26, 2007 03:56

Re: Estimating pressure drop from the shear stress
 
You can estimate the shear stresses or anything else like velocity , mass flowrate....etc at the wall or any section in your domain by going to the menu report>surface integrals then Fluent can compute the values of these parameters at any section you want as i mentioned.The Blasius law is very simple law to estimate the friction factors in the pipes from Rynolds number and there is different laws for it in laminar and turbulent flow, but in FLUENT we not use it because the friection factors can be estimated directly from the shear stresses from the relation f(friction factor)=shear stress/(2*density*velocity^2)I am not sure If i wrote this relation correctly you can check it from any CFD book.About me i am using the VOF model I have 2 phase stratified flow in a pipe I want now to estimate the pressure drop from the shear stresses at the wall and at the interface but i do not which relation should I use for this? Hope my commend about your enquiry be useful.

K.Baker



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