[Gmsh] Questions regarding Boundary layer meshing

[Kushagra Vidyarthi]

Dear Gmsh Experts,

I'm a newbie with Gmsh and open-source softwares, and as my first 
project, I'm trying to do a 2D CFD simulation around an airfoil using 
openFOAM. I want to develop a method which I can use in all future CFD 
projects. For this reason, I'm trying to simulate flow around a NACA 
airfoil, for which standard test data is available. I'm using a c-grid 
hexa mesh for the airfoil. Initial trials have produced results which 
are a bit erroneous. I believe the problem can be solved by producing a 
good boundary layer mesh, with a suitable first layer distance based on 
a y+ value. But I cannot find a good source which would guide me through 
the process of specifying a first layer distance of the mesh from the 
airfoil wall. Kindly tell me a method (set of commands and how to use 
them) I can use to do what I intend to do or, if possible, point me to a 
source which would give a proper tutorial on how to do a good boundary 
layer mesh.

Thanks and regards,

Kushagra Vidyarthi