Minimum L/D for DarcyûWeisbach equation
Minimum L/D for DarcyûWeisbach equation
(OP)
Is there some value of L/D for which the Darcy–Weisbach equation is applicable?
At what point does 'relative roughness' become meaningless?
Is there any expectation of accuracy in calculating the pressure drop through a 10-foot steel duct that is 5 feet long?
Seemingly not because the flow is not close to "fully developed" in such a short length.
For such a short duct, how meaningful are the friction factor based on e/D (in this example = 0.15/10 = 0.015) and the pressure drop based on L/D (in this example = 0.5)?
If using an orifice equation, what is an appropriate value for C_d, coefficient of discharge for the incompressible flow equation in Wikipedia:
http://en.wikipedia.org/wiki/Orifice_plate
Or is some other calculation more appropriate for this situation?
At what point does 'relative roughness' become meaningless?
Is there any expectation of accuracy in calculating the pressure drop through a 10-foot steel duct that is 5 feet long?
Seemingly not because the flow is not close to "fully developed" in such a short length.
For such a short duct, how meaningful are the friction factor based on e/D (in this example = 0.15/10 = 0.015) and the pressure drop based on L/D (in this example = 0.5)?
If using an orifice equation, what is an appropriate value for C_d, coefficient of discharge for the incompressible flow equation in Wikipedia:
http://en.wikipedia.org/wiki/Orifice_plate
Or is some other calculation more appropriate for this situation?





RE: Minimum L/D for DarcyûWeisbach equation
RE: Minimum L/D for DarcyûWeisbach equation
RE: Minimum L/D for DarcyûWeisbach equation
For a conduit between reservoirs I don't imagine the flow is fully developed if L/D < 10. There may be a better limit, but I suppose L/D = 0.5 for a conduit between reservoirs isn't even close to an appropriate application of the Darcy–Weisbach equation.
Thanks.