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Fluid Flow Around NACA2412 Airfoil

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Old   December 9, 2016, 17:25
Arrow Fluid Flow Around NACA2412 Airfoil
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MURAT GÜNEŞ
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Hi everyone,

I have a GRADUATION THESIS that is Fluid Flow Around NACA2412 Airfoil. I'll discuss Cl and Cd at different attack angle.However, I have a problem after zero attack angle in fluent. For example, at the 5 attack angle Cl and Cd values don't match with the experimental values, so I can't have costant value for Cl/Cd. What is the problem? mesh or boundary conditions or y+ value? I need help immediately.

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Murat Gunes
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Old   December 13, 2016, 11:52
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Hi,

the y+ value depends on the turbulence model (SA, k-e, SST etc.) you are using and if you use or not wall functions. Describe your case.

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Old   December 13, 2016, 14:40
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I'm using the sst turbulent model.
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Old   December 16, 2016, 18:16
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So you need y+<1


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Old   December 17, 2016, 03:09
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Quote:
Originally Posted by fanch33 View Post
Hi,

the y+ value depends on the turbulence model (SA, k-e, SST etc.) you are using and if you use or not wall functions

Fanch
This is misleading statement.

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So you need y+<1


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Really? Why?
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Old   December 17, 2016, 06:26
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The SST allows the resolution of the boundary layer all the way down to the wall and work as a low Reynolds number, so you need to ensure that y+<1


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Old   December 17, 2016, 07:45
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The SST allows the resolution of the boundary layer all the way down to the wall and work as a low Reynolds number, so you need to ensure that y+<1


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Yes it allows it, but it doesn't mean that one needs it and that y+ needs to be < 1 for this.
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Old   December 17, 2016, 07:52
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It means that the sub viscous layer must be resolved so y+<5 ...
But y+<1 is better ...
Do as you want



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Old   December 17, 2016, 08:09
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Quote:
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It means that the sub viscous layer must be resolved so y+<5 ...
But y+<1 is better ...
Do as you want

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y+ = 1 is the lowest limit.
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Old   December 19, 2016, 16:03
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The performance of a wing has a critical influence on the overall performance of the airplane impacting the range, speed, climb rate, payload, maneuverability, runway length, etc. Performance degradation is often the result of flow separation over the wing. Adverse pressure gradient with low flow velocities in the boundary layer causes flow separation on the wing leading to significant reduction in lift. The prediction of flow behavior over the range of operating conditions in a flight is thus very crucial for optimal design and safety consideration.
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