Cross section changes in a wave guide (2)
The cross section change between the two ducts is shown by a transition zone.
In the transistion zone, the following phenomena exist:
The volume velocity changes abruptly in the cross section of the big waveguide in the transistion zone.
Between
and
, there is a field expansion due to the conservation of flow between the input and output of the junction (
)As the fluid is deformable (air), the transistion is very fast, thus the transistion zone is very small (
). In the case of slightly deformable fluid (oil for example), the transition zone will be a lot bigger.Outside of this zone, we retain
and
By choosing global variables for pressure and volume velocity, the cross section does not need to be represented.
