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March 23, 2013, 10:50 |
entrance length
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#1 |
Senior Member
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 17 |
Dear friends
in a pipe flow, How to find the entrance length for fully developed ideal flow? I have defined the inlet velocity as function of time, in such case how do I find the entrace length? Thank you |
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March 25, 2013, 08:34 |
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#2 |
Senior Member
Edmund Singer P.E.
Join Date: Aug 2010
Location: Minneapolis, MN
Posts: 511
Rep Power: 20 |
In your CFD model?
Measure it? Use textbook calc? What do you mean? |
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March 25, 2013, 10:56 |
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#3 |
Senior Member
OJ
Join Date: Apr 2012
Location: United Kindom
Posts: 473
Rep Power: 20 |
Laminar: L/D=0.06 Re
Turbulent: L/D=4.4 Re^(1/6) L is entrance length, D diameter. Any textbook should cover this. The fully developed flow is defined as the flow with no velocity gradients in flow directions. This should automatically imply steady state, since for transient case, the velocity profiles may change. Ultimately, even if you start as transient simulation, it will converge to a fully developed steady state solution. OJ |
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