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Ways to reduce entrance length

For a cylindrical tube with diameter D leading to a rectangle channel with width 3D-4D, what kind of inlet condition is suitable in reducing the entrance length to achieve plane Poiseuille flow.

The velocity in the tube is quite high (2 times the average in the channel) and an aim is to prevent this high velocity fluid from affecting the rectangle channel. I was thinking of placing an obstruction of sorts to "distribute" the fluid evenly across the channel width. Not sure if this is plausible. Comments appreciated.

Thanks philip

Reply to
Philip
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Dear Philip:

A sheet with lots of relatively small holes in it. Oriented perpendicular to flow. Establishes a sort of "flat" velocity profile.

David A. Smith

Reply to
N:dlzc D:aol T:com (dlzc)

Unfortunately, this is not feasible as there are small particles in the fluid.

Reply to
Philip

1) filter it, or 2) install a "large" "egg" in the flow stream, centered. Pointy end faces into the flow stream.

As an "egg"zample. 2) will give you a velocity profile that will settle out pretty fast, since shear is forced high at the walls... and the fluid in the center is moving relatively slowly.

David A. Smith

Reply to
N:dlzc D:aol T:com (dlzc)

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