I am having trouble getting my residuals to decrease nicely with no oscillation. I have refined my mesh numerous times, as well as increased the flow domain, especially moving the outlet further far field from the airfoil but to no avail. I have attached a picture of the residuals plot that I get.. And this is after 5000 iterations. I have also included a photo of my mesh which I believe to be in good condition. The orthogonal quality is good and the skewness is below 0.95.
Properties of the 2 Element Airfoil:
Mainplane - 0 AoA, Flap - 25 AoA, Overall chord length - ~1.2 m
Velocity Inlet - 14 m/s in the x-direction
Top and Bottom - Stationary Wall with Specified Shear components set at 0
Outlet - 0 Gauge pressure outlet
The results make physical sense but the residuals are leading me to believe that I shouldn't take this values as accurate. This is for my degree project so accuracy is key.
Any help is greatly appreciated. Thank you