**MESH INFLUENCE ON AIRFOIL TEST**

This part of the project will be devoted to the study of three different meshes:

* The coarse structured mesh shown below:

Srtuctured coarse mesh

* The coarse structured mesh refined close to the airfoil:

Refined structured coarse mesh

* An unstructured mesh described below:

Unstructured mesh.

We
have tested those three meshes with exactly the same parameters. The following
figure represents

the calculated residuals of the volumic mass evoluating with iterations.

We
can see that the precision for the structured mesh has a limit around 1000
iterations. Then for this case too much iterations are not usefull. The
refined structured mesh improve the convergence of about three

order of precision. However, this second calculation was longer than
the first one. The unstructured mesh also has a better precision.

Therefore the third mesh
seems to be more efficient. We will now look more precisely at results
obtained

with each mesh. The following figures represent the evolution of mach
number, after 10000 iterations, for the different meshes.

Iso-Mach lines for the structured mesh

Iso-Mach lines for the refined structured mesh

Iso-Mach lines for the unstructured mesh

We
can see in those figures that, although the unstructured mesh gets a better
precision with the residual study, it is less clear when we look at the
ending shock on the airfoil. However, the refined structured mesh gives
a better result. Therefore the use of unstructured mesh seems not to improve
results although it improve

precision.