By default, the boundaries of the simulation region are closed.
This means that the extent of simulation is determined by the simulation region boundaries.
In our example, selecting the simulation region object while being in partitioned volume mode
will reveal that the simulation area is limited to the simulation region box in all directions.
On the other hand, users have the option to leave the simulation region boundaries open.
This means that the extent of simulation is defined by the structure shape not the simulation
When selected, an open simulation boundary extends the boundary to the surface of the
outer structure in the corresponding direction.
Here, for example if I leave the boundaries open in the X direction, it is obvious that
my simulation area is now limited to the surface of sphere and rectangle objects in the X direction.
If I repeat the same for the other direction, my simulation region is defined by geometric
objects boundaries in all directions as shown here.
This feature can be useful for limiting the simulation only to the areas of interest.