Wrong results for lift force every simulation

henriquecar · June 16, 2019, 12:37

Hello guys.

I am simulating a steady-state water flow past a bare hull underwater vehicle in ANSYS Fluent for validating purposes based on an article. The problem is that for every velocity and angle of attack the drag coefficient is correct but the lift coefficient is off by up to 50%. I have performed mesh dependency tests, tried several turbulence models, increased/decreased inflation layer size and y+, but still failing to understand the cause.

I've also turned up the gravity effect but I got no difference in the results whatsoever. Could this be because the weight is being balanced by the buoyant force? Or it is not balanced and there is no weight because the geometry is defined as hollow (I only have surfaces defining the hull body because I have used a subtract boolean feature).

Any help is appreciated. Thank you in advance!

jaydevadve · March 19, 2021, 15:23

I am simulating a fuselage, and had used every combination of models possible. But still drag is expected and correct as well while lift is totally wrong.
Hey did you get any solution?

tahar · March 21, 2021, 08:58

tray to check the reference value or use UDF such as " excute at end" to calculate lift

June 16, 2019, 12:37	Wrong results for lift force every simulation	#1
henriquecar New Member Henrique Carneiro Join Date: Jan 2019 Posts: 4 Rep Power: 7	Hello guys. I am simulating a steady-state water flow past a bare hull underwater vehicle in ANSYS Fluent for validating purposes based on an article. The problem is that for every velocity and angle of attack the drag coefficient is correct but the lift coefficient is off by up to 50%. I have performed mesh dependency tests, tried several turbulence models, increased/decreased inflation layer size and y+, but still failing to understand the cause. I've also turned up the gravity effect but I got no difference in the results whatsoever. Could this be because the weight is being balanced by the buoyant force? Or it is not balanced and there is no weight because the geometry is defined as hollow (I only have surfaces defining the hull body because I have used a subtract boolean feature). Any help is appreciated. Thank you in advance! jaydevadve likes this.

March 19, 2021, 15:23	Same problem	#2
jaydevadve New Member Jaydev Dave Join Date: Mar 2021 Posts: 1 Rep Power: 0	I am simulating a fuselage, and had used every combination of models possible. But still drag is expected and correct as well while lift is totally wrong. Hey did you get any solution?

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March 21, 2021, 08:58		#3
tahar New Member moh Join Date: Jan 2014 Posts: 20 Rep Power: 12	tray to check the reference value or use UDF such as " excute at end" to calculate lift