Unphysical Rise of Water-surface near tail-gate

pratik_chakraborty · August 18, 2019, 13:20

I have been trying to simulate a flow over a spillway and in doing so I am looking to control the depth of water using a tailgate. The turbulence model is RAS;kOmega.

The issue herein is that there seems to be a bulge in the water level near the weir/tailgate (downstream of the spillway) which is rather unphysical. What could be the reason?

simrego · August 22, 2019, 04:21

Hi!

What you see is a hydraulic jump. I think it is not unphysical.
Google it and you will find more about this phenomenon.

pratik_chakraborty · August 22, 2019, 14:48

I do know that a jump is occurring at the weir but what I am saying is, the form of the jump (the shape i.e.) isn't what it is like in experimental setups - wherein the water surface is flat till the weir cross-section and thereafter drops.

Santiago · November 18, 2019, 14:12

Quote:

Originally Posted by pratik_chakraborty

I have been trying to simulate a flow over a spillway and in doing so I am looking to control the depth of water using a tailgate. The turbulence model is RAS;kOmega.

The issue herein is that there seems to be a bulge in the water level near the weir/tailgate (downstream of the spillway) which is rather unphysical. What could be the reason?

you have your inlet too close to the weir. In fact, you are incorrectly reproducing the forebay, since what I assume you are expecting is a tranquil flow (M3) upstream.

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August 22, 2019, 04:21		#2
simrego Senior Member anonymous Join Date: Jan 2016 Posts: 416 Rep Power: 14	Hi! What you see is a hydraulic jump. I think it is not unphysical. Google it and you will find more about this phenomenon.

August 22, 2019, 14:48		#3
pratik_chakraborty New Member Pratik Chakraborty Join Date: Aug 2019 Posts: 2 Rep Power: 0	I do know that a jump is occurring at the weir but what I am saying is, the form of the jump (the shape i.e.) isn't what it is like in experimental setups - wherein the water surface is flat till the weir cross-section and thereafter drops.