*The
first simulation with StarCd: turbulent flow*
* *The exterior
wall do not move whereas the interior one turns 30 revolutions per minutes.
The fluid is air.

There are
200 iterations, and the solution is converged. The Reynolds number is equal
to 300,000 so we are clearely in the turbulent area.

We have got
the following results.

If we make a profil of velocity, we find a linear curve. We can remark that the velocity is very important even near the exterior where the boundary condition impose a null velocity. That is a consequence of the turbulence because the diffusion is very important.

*The
second simulation: laminar flow*

To get a laminar
flow, we changed the fluid. We decided to take water because its viscosity
is higher and the convergence is consequently faster.

The fluid
is water with a viscosity of 0,4. The Reynolds number is equal to 500.

The results
is for 350 iterations.

First we can see a global view which shows the decreasing of the velocity with the increasing of the ray.

If we observe the velocity with a zoom, we wonder that in this case, the velocity tend to a null velocity in the exterior.

The profile shows us that the decreasing is a little bit parabolic, caracteristic of a Newtonien fluid.