# Hydraulic jump boundary conditions

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 November 28, 2022, 02:12 Hydraulic jump boundary conditions #1 New Member   layla Al- sabbagh Join Date: Nov 2022 Posts: 2 Rep Power: 0 Dear all, I´m trying to simulate the hydraulic jump below ogee spillway using flow 3d. The problem is I don't know which is better to use as a downstream BC: specified pressure (tail depth) or outflow.

 November 30, 2022, 05:09 #2 New Member   Sehroosh Join Date: Apr 2019 Location: Pakistan Posts: 25 Rep Power: 5 I would suggest to use 'specified pressure boundary'. There can be three variation in such boundary depending on your design conditions: 1) Pressure with fluid height => if you are maintaining a tailwater downstream of jump 2) Pressure with fluid fraction=1 => if the flow is sub-critical in the downstream reach 3) Pressure with fluid fraction=1 => if the flow is super-critical in the downstream reach layla Al- sabbagh likes this.

November 30, 2022, 09:11
#3
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layla Al- sabbagh
Join Date: Nov 2022
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Quote:
 Originally Posted by MSM1985 I would suggest to use 'specified pressure boundary'. There can be three variation in such boundary depending on your design conditions: 1) Pressure with fluid height => if you are maintaining a tailwater downstream of jump 2) Pressure with fluid fraction=1 => if the flow is sub-critical in the downstream reach 3) Pressure with fluid fraction=1 => if the flow is super-critical in the downstream reach
When i use pressure with fluid height corresponding to downstream depth of jump, is this boundary behave like outlet (outflow) or the flow may be return back.

 December 1, 2022, 05:03 #4 New Member   Sehroosh Join Date: Apr 2019 Location: Pakistan Posts: 25 Rep Power: 5 This will depend on hydraulic design of basin/jump. If Tailwater > Tailwater required, jump will moved towards chute; otherwise it will move towards downstream channel or might sweepout if tailwater < Min. tailwater required. The software just solve equations based on your input and model the exact situation. layla Al- sabbagh likes this.

 Tags boundary condition, hydraulic jump, tail depth