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Hydraulic jump boundary conditions

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Old   November 28, 2022, 02:12
Default Hydraulic jump boundary conditions
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layla Al- sabbagh
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Dear all,

Im 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.
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Old   November 30, 2022, 05:09
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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
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Old   November 30, 2022, 09:11
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Quote:
Originally Posted by MSM1985 View Post
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.
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Old   December 1, 2022, 05:03
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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.
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