hi all, I'm attempting to run a mesh convergence analysis and am running into issues. I am using simpleFoam to solve for steady turbulent flow over an aerofoil using Spalart-Almaras. I have a mesh with an outer section that I have made (I believe) suitably fine, and a boundary-layer mesh where I define the boundary layer thickness, the expansion ratio and the first cell thickness. I have set my first cell size to make y+ =1 and this result converges. When I refine this first cell thickness (keeping BL thickness and exp ratio the same) my results vary dramatically, and I am not seeing mesh convergence at all. What is happening here? My understanding is that refining a mesh should result in convergence, but I also don't fully understand the y+=1 criteria, and I'm also concerned about my first-cell aspect ratio, but checkMesh says the mesh is good for all refinements