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Old   August 18, 2013, 20:59
Question Flow forces
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Tunlu
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Hi, Everybody !

I would like to request to share me your knowledge !
I am working on flow force acting on a suspended bar by using Fluent.
The flow is perpendicularly targeted (let say Z direction) on a surface of the bar (let say X-Y plane) . I got the results ! When I extracted the flow force acting on that surface in Z direction, there was viscous force.
I would like to know Why? Thank you very much.

Tl
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Old   August 19, 2013, 02:15
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Alex
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How high is the contribution of shear forces to the total force?
Are you sure that it is not just a numerical artifact caused by the fact that the normal vector of the face (especially the normal vectors of the cell faces) are never identical with the z-direction?
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Old   August 20, 2013, 07:01
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Yes, Flotus1

The percentage of viscous force is about 0.2%. But, I like to see it as totally zero. It may be because of the fact that you said. Normal vector of faces of some element are not identical to the Z axis. Thus, viscous forces on that surface produce components in Z-axis. Right? So, we should not take account that viscous force, Right? Thank you very much, Flotus1.

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