hi, i would like to know what is the default unit for the mesh size in Fluent/ Gambit. and also how do i find out the density and the size of the mesh of my geometry from Gambit/ Fluent? help very much appreciated. thank you in advance.

I'm not but in gambit mesh is generated in [m]. You should always check your mesh in fluent by option grid>scale.If you have to large your mesh i.e sting the scale factor 0.001 Also you can check your mesh in fluent by grid>info.

You can make you mesh in any unit in Gambit (not just m). You then scale it (to m) in Fluent using the scale (convert function) and by specifying what ever unit you used for creating your mesh in unit. All meshes are converted to m when using fluent.