# difference betwen theory based solutions and numeric for heat tansfer

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 December 15, 2013, 19:29 difference betwen theory based solutions and numeric for heat tansfer #1 New Member   Gökhan Join Date: Dec 2012 Posts: 5 Rep Power: 6 Sponsored Links hi guys i have a problem with my basic analysis my case is a simple recalculation of 2d puiseulle flow with numerical. i have surface domain 1m x 40m and i made laminar flow inside with changing velocity inlet. i added constant heat flux at top and bottom wall with same value, for example 10w/m2. i expected that average outlet temperature have same value with calculated from theoritical equation. but it was not same. M^dot(mass flow inlet) x Cp x (Toutlet - Tinlet) =Qdot(heat flux) x A (area) in this equation with known mass flow inlet, Cp, heat flux and Tinlet, Toutlet can be calculated. But, calculating outlet temperature in cfd-post with drawing line at outlet and using calculator for average temp. at this line is not give same value with theory above. so, what i still have missed, it is a very basic convection relation and it has to be give same results with any simple numerical case

 December 24, 2013, 06:54 #2 Senior Member   Ahmed Join Date: Mar 2009 Location: NY Posts: 251 Rep Power: 11 it is spelled Poiseuille How did you calculate the outlet average temperature? Just to give you a tip, the left hand side of your energy balance is a thermodynamic relation, i.e. the temperatures there are Equilibrium Temperatures.

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