Handling of the sliding mesh interface for moving/deforming meshes involving launch problems
A sliding mesh interface is often needed for moving/deforming mesh cases. A class of problems for which this maybe necessary is the a launch
tube problem. In this cases you have a projectile residing within a barrel/launch tube. Let's assume that there is a significant tolerance between
the projectile and the tube and the geometry is such that a combination of hex/tri control volumes are needed (mostly due to the projectile/missile shape).
For that reason, multiple cell zones need to be created and a sliding interface. The side of the sliding interface that is closer to the enclosure may consist of one segment (created as one edge in Gambit) or multiple segments bundled together under the same name in boundary conditions. The same could
be true in the side of the interface that belongs to the missile/projectile zones. If one is not careful in creating the sliding mesh interface properly, then
there is going to be miss-communication between the interfaces and an artificial wall will be created not allowing the flow to go across the interface.
The solution for this problem is as follows:
It is important that the user does not break down the sliding interface in two or more segments. If this happens
then the deforming sliding mesh interface will end up trying to communicate and interpolate data with a segment
of the exterior interface that it was not set up to work with initially. It is important for the users to understand,
that in sutuations like that, the interface that is closer to the missile is deforming, wheras the interface that is
closer to the canister or launch tube is not. For that reason, all different segments on either side of a sliding
mesh interface have to be part of one interface so that there can always be interpolation between the two interfaces.