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Mass flow rate through a surface towards specified direction

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Old   September 3, 2019, 13:04
Default Mass flow rate through a surface towards specified direction
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Hi, I need to calculate mass flow rate or velocity through a surface towards specified direction. This surface represents inlet of a sack (closed volume). There is a reverse flow at this surface (towards out of the sack) I need to calculate mass flow rate in to the sack. Is it possible?
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Old   September 3, 2019, 18:26
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Yes, the massFlow() CEL expression works it out for you, and includes the effect of any backflow.
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Old   September 4, 2019, 14:26
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That's the point, ı don't want to include back flow
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Old   September 4, 2019, 19:18
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In the documentation (CFX Reference guide, massflow CEL function) it states that the approximate mass flow can be evaluated by "areaInt_x(Velocity u * Density)@myLoc + areaInt_y(Velocity v * Density)@myLoc + areaInt_z(Velocity w * Density)@myLoc". You can modify this equation by setting the velocity at regions of reverse flow to zero velocity.
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Old   September 6, 2019, 12:28
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Hi, first of all thanks for your attention and help. I have tried what you have suggested unfortunately did not work out for me. I need to calculate only velocity (+w). Thanks to you now i am able to monitor towards an axis, is it possible to specify (+w) or (-w) as well?
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Old   September 7, 2019, 07:01
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It appears you missed the sentence which read "You can modify this equation by setting the velocity at regions of reverse flow to zero velocity."

It is always better if you figure these things out for yourself, but now I know you want positive w only and not negative w and u and v can be ignored, the equation becomes "areaInt_z(absVal(Velocity w) * Density)@myLoc". (I am not sure about the "absVal" function and cannot look it up as I am not at work. You will have to check this is the correct function in the CFX reference manual, the section on CEL Functions)
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