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Average Velocity at Inlet/Outlet from derived values (after simulation) does not match the input average velocity

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Hello,

So, I am simulating a U-tube heat exchanger. I have an inlet and outlet defined for my simulation, and I input a .11 m/s normal inflow velocity. However, when I take the average velocity at the inlet or get the volumetric flow and divide by the surface area of the inlet, I get a value of .08m/s for the average velocity after the simulation runs.

Is this normal, or am I doing something wrong? My simulation file is too big to attach here even after deleting the results/study/mesh. Please let me know if you need any additional information.

Thank you very much for your time! -Dan


2 Replies Last Post 1 oct. 2018, 10:16 UTC−4
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist

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Posted: 6 years ago 26 sept. 2018, 12:47 UTC−4

Please provide how you are performing the averaging.

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James D. Freels, Ph.D., P.E.
Please provide how you are performing the averaging.

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Posted: 6 years ago 1 oct. 2018, 10:16 UTC−4

Please provide how you are performing the averaging.

boundary probe? i meet with a similar problem... mass is not balanced between inlets and outlets... i don't know why

>Please provide how you are performing the averaging. boundary probe? i meet with a similar problem... mass is not balanced between inlets and outlets... i don't know why

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