body info in salome

Hi,

I have a part that it has 3 partitions (or called 3 volumes).  Each partition/volume is one kind of material.  The faces common to two partitions are connected, so that, the nodes are identical from both sides of the partition.

After meshing the partitions, I created 3 groups, each group (with elements) is for each partition.  Exported to unv file.  I noticed one problem.  In the element section (2412) below, the 4th number indicates which body this element belongs to. 

-1

2412

1 111 1 5 7 4 104 46 29 30

In salome,  becasue there is only 1 mesh, so, they all belong to the same body.  The only way to tell them apart is to write a simple code to look through the groups section and change the 4th value on each element to the correct group number.

Is there an easier way to do this in Salome? 

If I mesh each partition indivisually (mesh1, mesh2, mesh3), how can I merge them together later? and how can identical nodes on the common faces be guarantted?  Will the elements from each mesh be assigned different value in the 4th number of the element section?

The goal is to do conjugate heat transfer.  There are several solid parts and fluid elements.  I need to be able to assign different material properties to each part.

It will be appreciated if you can shed some light on this?

phsieh2005