I have done CFD Analysis in Solidworks Flow simulation with Boeing 737-800 Aircraft.

and set Angle of attack 1.5 degree initially. and run another case with angle of attack 2.5 degree.

After solution converged I got more drag in case of 1.5 AoA  which was about 22,000 N than 2.5 AoA which was about 18000 N.

But usually Drag increase with the increase of AoA.

Can anyone clarify the issue please?