#
__Physical issue__

This part is aimed at showing the shape of our
domain and to introduce the geometry on which we will have to work and
to discretize.

The problem is, as said previously, to simulate what
happens in a particle filter, when particles are launched at the inlet
of the domain.

We have chosen the following geometry as representative
for most of the cases. At least, it remains a very common case and the
size has been chosen to be realistic.

Here is the shape of the filter.

As you can see, we have chosen to let an area
before the real inlet of the filter, so that the flow could be established.
The other solution would have been to impose the boundary conditions directly
in the first entry near the wall.

The filter is in fact constituted of lot of such elementary
filters. Here, we consider only one small segment, to have an idea of the
phenomena.

Here is a picture in three dimensions, thanks to StarCD,
which obliges us to work with a 3-dimension model.

For further details, you can have a look at the next
chapter, which deals with the mesh, boundary conditions and strategic decisions.

- the filter in 3D -
Next