Baffled outlet problem (6 Minute Solutions WR)

[civil-nj]

Hello all,

I'm stuck on the attached problem and would appreciate your help!

It's from the Six Minute Solutions Water Resources book. (3rd edition, pg. 7, Problem 22).

I spent a good bit of time going over the solution in the back of the book, and I STILL don't get it. Feeling pretty stupid... :brickwall:

Let me know when you want me to post the solution.

Thanks!

civil-nj

 

[civil-nj]

Here is the solution and a more specific question:

Here's the concept I don't understand...why do you use the Froude number in the following equation? What conditions are being met that make D_b the "minimum required depth?"

 

[Blacktop]

I'm just throwing this out there, I'm not even sure this is in the right direction, but...

Do you think this situation might be analyzed as a sluice gate? I might look into trying to solve it that way, maybe then the reason behind the minimum Db will become apparent(?)