CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

High drag values when increase angle of attack

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   February 28, 2022, 14:06
Exclamation High drag values when increase angle of attack
New Member
Join Date: Oct 2021
Location: Italy
Posts: 6
Rep Power: 4
alc96 is on a distinguished road
Hi guys,

I'm trying to validate a turbulent flow around NACA0012 at Reynolds number 2e+6. My mesh is structured around the airfoil with y+ < 1 and unstructured outside the airfoil. The mesh is generated with Gmsh. I am using the Spalart-Allmaras turbulence model.

Now the thing is that the lift coefficient follow the experimental curve, but the drag coefficient is in agree at low angle of attack (0-4 degree) but from angle of attack = 5-6 increase a lot with relative error of 200% !!!

At the inlet I have set nut = nuTilda = 0.12 calculated from the turbulent kinetic energy k and the dissipation rate epsilon:

k = 3/2*(U*I)^2 with I = 0.02 and U = 50 m/s (M = 0.15);

epsilon = cmu*(k^1.5)/l with cmu = 0.09 and l/c = 0.1 being l the turbulence length scale and c = 1 m the airfoil chord.

nut = nuTilda = cmu*k^2/epsilon

I have also read that at the inlet vt can be computed as vt = 0.1*v (v = 2.5e-5 in my case) but in this case the simulation crashes because I have the error bounding nuTilda after few iteration.

How can I solve this problem ?

Thank you very much !!
alc96 is offline   Reply With Quote


drag coeffcients, openfoam, spalart allmaras, turbulence, validation

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Calculating Oscillating Aerofoil Angle of Attack MechEng86 FLUENT 1 August 20, 2019 08:19
Airfoil with simpleFoam and kOmegaSST: high drag values? Tsiolkovsky OpenFOAM Running, Solving & CFD 6 November 21, 2018 05:56
High CL lift coefficient in Stall Angle of attack airfoil restuesaputra FLUENT 0 April 26, 2016 20:27
Separated flow over single fowler flap attaches after increase in angle of attack Sonil Main CFD Forum 2 March 1, 2012 00:12
Lift and Drag Monitor Point Values Converging to Zero Josh CFX 24 May 9, 2011 10:38

All times are GMT -4. The time now is 22:42.