# Pressure Drop due to Friction

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 April 29, 2012, 23:22 Pressure Drop due to Friction #1 New Member   sam Join Date: Nov 2011 Posts: 25 Rep Power: 5 Hi, Let me Explain the conditions of problem. Pipe Ø4mm, 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 __________________ Regards, Sam

 April 30, 2012, 09:49 #2 Member   Ryan Coe Join Date: Jun 2010 Location: Albuquerque, NM Posts: 98 Rep Power: 7 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. __________________ Ryan

May 2, 2012, 01:30
Pressure drop due to friction
#3
New Member

sam
Join Date: Nov 2011
Posts: 25
Rep Power: 5
Quote:
 Originally Posted by ryancoe 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.

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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
__________________
Regards,
Sam

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