Expansion/Contraction Coefficient Determination

[Anonymous]

I have a channel that is transitioning from a 80′ top width to a 60′ top width (capacity is reduced considerably from the upstream to the downstream cross-section). The distance between the two sections is approximately 185′, and there is no bridge/culvert involved.
I am currently using the standard 0.1 and 0.3 contraction and expansion coefficients for the upstream section. Should I be using 0.3 and 0.5 instead, since the flow is being forced into the smaller cross-section? What are your thoughts on this?

I appreciate any help/advice I can get!

Thanks,

[Anonymous]

in your case the b/B ratio is 60/80=0.75. For this value a Contraction Coefficient of 0.1 is typically used in bridges transitions. You can also interpolate between the XS’s to the transition is smoother.

[Author]

Posts