2D mesh for external flow computation (batch and tui)

Dear All,

I'm trying to make a 2D mesh for external CFD computation.
In order to do that I use a modified version of the script Erwan put in his web site.
Everything works fine (both in tui and in batch), but the resulting mesh is quite strange and I'm not able to understand what goes wrong.

I put the script on the page http://xoomer.virgilio.it/edmondo_minisci/airfoil_batch_mesh.py
and a screen shot of the resulting mesh on the page http://xoomer.virgilio.it/edmondo_minisci/grids.html

As you can see, the triangle area does not change in a monotonic way from the fine zone (near the airfoil) to the coarse one ("external" field).

Does anybody know what the problem could be?

Thanks and the bests

Edmondo