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-   -   Pressure Drop due to Friction (http://www.cfd-online.com/Forums/star-ccm/101267-pressure-drop-due-friction.html)

Sam0508 April 29, 2012 23:22

Pressure Drop due to Friction
 
Hi,
Let me Explain the conditions of problem.

Pipe 4mm, Air velocity 50m/s, Turbulent flow, Dy viscosity 1.79E-5 N.S/m2, Density of Air 1.23kg/m3.Need of finding the Pressure Drop for 0.1m length.

The Calculation value is 1.076kPa,but in STAR CCM+ got value as 1.255kPa.In software i specified the B.C as Inlet-Velocity inlet 50m/s and outlet-massflow outlet -7.539E-9 kg/s and mentioned Roughness Height also for account of friction factor.

In physics continuum..Constant density/Segregated flow/Steady state/K-Epsilon Turbulence.

Can u tell me what i did wrong in software?



Thankyou,
Sam0508

ryancoe April 30, 2012 09:49

What is your 'calculation' value (is it from an empirical experiment)? If so, the CFD and empirical calculation should not necessarily be expected to match exactly.

Sam0508 May 2, 2012 01:30

Pressure drop due to friction
 
Quote:

Originally Posted by ryancoe (Post 358473)
What is your 'calculation' value (is it from an empirical experiment)? If so, the CFD and empirical calculation should not necessarily be expected to match exactly.


----****----

Hi Ryan Coe,
It's not a experimental value, found by normal Dp(Pressure drop) Derived equation.i.e

Dp=(f*L*rho*V2)/(2*D) Dp units Pa
[f= friction factor(beased on Reynolds No and Relative Roughness), L=Pipe lenght 0.1m, rho=Density of Air, V= velocity of air 50m/s and D=Pipe diameter]

Why this values is not match with Theoritical data/Derived one.the difference(STAR CCM+ result Dp-Theoritical Dp result) is 170Pa,how we can accept? or What i did mistakes in this. Plz give ur feedback.Thankyou


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