Engineering Homework Help

In this question, the first step is to get Fr value, I don’t really understand why we need to get this value

Exercise 6Water is flowing at a velocity of 3 m/s and a depth of 3 m in a channel of rectangularcross-section. Find the maximum allowable size of upward step for the upstream flowto remain as specified.SolutionFr = -3V9.81 x3= 0.55 – The flow regime is subcritical.The unit discharge is_q=v*y=9m’ IsSpecific Energy in the cross-section is_32E=y+2g=3+2×9.81-= 3.459mThe maximum size of the step which will not change the depth and velocity upstreamwill be one on which the critical depth will be formed.The critical depth is:Fr’ =19.81x yeyo = 2.02 mThe Specific Energy on the step is:E. = =y. = =x2.021 = 3.033 mTherefore the step size is:Az = E-E. =3.459-3.032Az = 0.427 mIf the step is above 0.427 m, the specific energy in front of the step (i.e. the depth) willincrease while the critical depth will form on the step.

 
"Our Prices Start at $11.99. As Our First Client, Use Coupon Code GET15 to claim 15% Discount This Month!!"