Hello, I have a basic(?)fluid mechanics question which is crossing my mind very often.Suppose that water is flowing in a pipe at 2 cu.m /sec at a pressure of 10 bar.If the pipe branches into two so that each pipe carries 1 cu.m /sec of water ,my question is what will be the pressure in each of the branched pipe.Some of my colleagus say it can be 10 bar itself,then if there are more than 2 branches will it be 10 bar in each branch again.

I am not able to resort to using the Bernoulli eqn. for this.I thought of considering the theory of flow through parallel pipes which says that friction losses will be the same in each pipe,but the fate of pressure values in the branched pipes are not normally discussed in classical flid mechanics books. Regards and thanks, asok

If the flow branches into two pipes you will have essentially a pressure drop due to the discontinuity in the flow that is equal to dH = sigma * rho * u^2/(2*g) dH = pressure loss, rho = density, u = velocity, g = gravity. sigma depends on the types of branches you have.

Chris.

Dear Mr.Chris Louche, Is the velocity in the expression the main pipe velocity or the branch velocity.Can you kindly refer me to some book where such a problem has been discussed.May I have a clue of how the expression is got.It happens to be the velocity head term in the Bernoulli eqn. Thanks and regards, asoksp

Dear S.P.Asok, Here are the answers to your questions : 1. The velocity in the expression corresponds to the main pipe velocity. 2. The reference book I've got is in french traduction of the russian book : "Memento of head losses", I.E. Idel'cik (don't know if there is an English version?) Everything is explained here. 3. If you give me the exact geometry of your branches (cross-section of the main pipe and branches, angle) , maybe I could e-mail you more references and the way to evaluate sigma for each branches (that allow you to calculate dP1 and dP2).

Dear Mr.Chris Louche, Thank you very much for quoting a nice reference book.I will come back after looking into it.Fortunately,the English version of nthe book seems to be available.Regards, asok

[elias_wehr]

I´m sorry to bring this discussion back.
But I can´t find any english version of the Idel'cik´s book.

Could some one point me out?

Thanks,
Elias