Hydraulic Jump

[alejo12]

hi ,

Is it safe to use delta E=(d2-d1)^2 / 4d1d2 or should I always solve for the energy loss with the upsteam velocity and the down stream velocity ( v1 and v2 ) CERM 11 edition , page 19-22 ?

 

[Guest]

You should always go back to the fundamentals for hydraulic jump since it is predicated on energy loss from the bernoulli equation. The energy equation your provided is for a jump with a rectangular cross sectional geometry, so it will only apply in the circumstance that you know the geometry.

JR

 

[sac_engineer]

Usually you would have to calculate d2 based on the upstream parameters of d1, so the specific energy loss equation wouldn't apply. That's actually the easy part the depths have been solved.

Hydraulic jumps are indeed based on Bernoulli's equation, but there are tables and graphs that correlate the upstream Froude number (based on d1 and v1) with the final depth (d2), length of hydraulic jump, and head loss, so you won't be bogged down substituting variables in the traditional equations.

Good luck!

 

[civilized_naah]

Hydraulic jumps are indeed based on Bernoulli's equation, but there are tables and graphs that correlate the upstream Froude number (based on d1 and v1) with the final depth (d2), length of hydraulic jump, and head loss, so you won't be bogged down substituting variables in the traditional equations.
Good luck!

Actually, applying Bernoulli's equation (conservation of energy) between the 2 locations won't yield the relations for a Hydraulic Jump. It is based on the principle of Conservation of Momentum.