basic fluid dynamics question: Flow though time

spalartallmaras · May 14, 2020, 19:24

Hello,

let we think we simulate air flow on an airfoil. The length of airfoil is 1 m.

And the CFD-Domain has 30 m in the direction of the flow.

Velocity is 30 m/s.

then in this case, my flow though time is...

1. 1 s? or
2. 1/30 s?

I think 1/30 s is right...

MikeBravo · May 14, 2020, 20:06

I'd say that is completely up to you, if you want it to be a complete domain flow-through or an airfoil flow-through. For my work on channel flows we define a flow-through as the time it takes from the domain inlet to the domain outlet, but your problem is different.
Also, if such accuracy would be desired, remember that the flow-through time for the suction surface of the airfoil will be shorter than for the pressure surface, but I doubt that level of accuracy is what you're looking for!

LuckyTran · May 15, 2020, 02:32

Flow thru time is 1 s. 1/30 seconds isn't the right answer, it's wishful thinking.

It's the same as channel flow, the initial condition needs to get washed out completely

May 14, 2020, 19:24	basic fluid dynamics question: Flow though time	#1
spalartallmaras Member niewiemnic Join Date: Jan 2018 Location: Niemcy Posts: 80 Rep Power: 8	Hello, let we think we simulate air flow on an airfoil. The length of airfoil is 1 m. And the CFD-Domain has 30 m in the direction of the flow. Velocity is 30 m/s. then in this case, my flow though time is... 1. 1 s? or 2. 1/30 s? I think 1/30 s is right...

May 15, 2020, 02:32		#3
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,676 Rep Power: 66	Flow thru time is 1 s. 1/30 seconds isn't the right answer, it's wishful thinking. It's the same as channel flow, the initial condition needs to get washed out completely arjun likes this.

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May 14, 2020, 20:06		#2
MikeBravo New Member Mike Join Date: Jan 2018 Posts: 29 Blog Entries: 6 Rep Power: 8	I'd say that is completely up to you, if you want it to be a complete domain flow-through or an airfoil flow-through. For my work on channel flows we define a flow-through as the time it takes from the domain inlet to the domain outlet, but your problem is different. Also, if such accuracy would be desired, remember that the flow-through time for the suction surface of the airfoil will be shorter than for the pressure surface, but I doubt that level of accuracy is what you're looking for!