Getting a Negative Drag_Coefficient
 

Hello Everyone

I am running a 2D simulation over a Airfoil via Fluent.

I am getting a good Lift Coefficient, but a negative Drag coefficient.

Is there anyone experiencing the same issues while running the CFD?

Besides, for the initialization method. Is there difference for Hybird and Standard initialization. which one is better?

please check
1) is your mesh fine enogh.
2) is your solution converged.
3) values for force vectors, are they defined correctly for specified AoA.

I think the Mesh is fine, I got a decent Lift_coefficient already

for the (3), what is values for force vector?, for the angle of attack, in the farfield setting, the direction of incoming air is defined based on x, y unit vector component.
for zero AOA, x:1 y:0 right?

yes,
for(drag monitor) specific AoA
X=cos(AoA)
Y=sin(AoA)

Hi,

Is direction vector correctly defined while calculation of drag ?
sometimes happened, while defining opposite direction of vector which reflects negative value.