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congsu April 30, 2012 22:24

energy loss of flow
 
Hello,
I want to calculate the energy loss of flow through some obstacle (cylinders, ..). In my opinion, I think the velocity magnitude at outlet boundary will smaller than input. But the result is both velocity magnitude (u,v,w), are same at inlet and outlet
I setup inlet_velocity and outflow for boundaries. (model 3D,_LES, transient)
Any one can help me, give me advices.
thank you!

xrs333 May 1, 2012 07:50

Hi, Suong,
i think i can explain it.
i guess you are modeling incompressible flow, that is density is constant. So, according to mass conservation law, mass flows are the same for inlet and outlet in steady flow. Furthermore, if the area is same for the inlet and outlet, the velocity magnitude will be same.
Energy loss for in flow should be evaluated with total pressure, which is the mechanical energy of the fluid.

congsu May 5, 2012 10:06

Quote:

Originally Posted by xrs333 (Post 358624)
Hi, Suong,
i think i can explain it.
i guess you are modeling incompressible flow, that is density is constant. So, according to mass conservation law, mass flows are the same for inlet and outlet in steady flow. Furthermore, if the area is same for the inlet and outlet, the velocity magnitude will be same.
Energy loss for in flow should be evaluated with total pressure, which is the mechanical energy of the fluid.

thanks for your explaination


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