when the angle of attack =?, the total lift coefficient begin to decrease suddenly
 

when the angle of attack =?, the total lift coefficient begin to decrease suddenly. Here, I consider the NACA0012 airfoil, freestream air speed=30m/s

ehmmm, stall?

here the airfoil is fixed. we conpute the flow with different attack angles from 0 degree to 18 degree. we want to know when the lift begins to decrease.

Okay, I misunderstood your question. Well that depends on the Reynolds number, so you need to provide the chord length of your airfoil and the flow conditions (standard athmospheric ?).

air density =1.225;
temperature T0=273.16;
chord length of NACA0012 airfoil is 300mm.
freestream air speed=30m/s
viscous coefficient mu=1.7161e-5
Reynolds number:70946

air density =1.225;
temperature T0=273.16;
chord length of NACA0012 airfoil is 300mm.
freestream air speed=30m/s
viscous coefficient mu=1.7161e-5
Reynolds number:70946

velocity inlet in fluent
 

Dear friends,
In fluent, For analysis of 2D naca0012 airfoil velocity inlet we give vcostheta in x component & vsintheta in y component, v is inlet velocity.

1)here i start analysis of 3D wing, for that i take naca 0012 airfoil & extrude 100mm, in gambit and analysis in fluent i have doubt how to set velocity inlet, here i consider my velocity is 50m/s, then what is xyz component,please let me know.

2)if you consider 3D wing, (vtantheta for z component) is correct or wrong, please let me know.

2) how to find angle of attack for 3D wing? please let me know