This is an extreme case of laminar flow where viscous (friction) effects are much greater than inertial forces.
His main research area was fluid flows with viscous effects.
The codes typically have a boundary layer analysis included, so that viscous effects can be modeled.
You will not capture viscous effects except via user "modeling" by changing the geometry.
Some problems may encounter only very small viscous effects on the solution, in which case viscosity can be considered to be negligible.
This means that viscous effects are much more important to the smaller insects, although the flow is still laminar, even in the largest fliers.
When not in a vacuum, i.e., falling through the air, there are viscous effects which affect the rates.
However, this problem specifies a closed container so the viscous effects act only on the container.
The Fanno flow model is considered an irreversible process due to viscous effects.
Then, the stress relaxes over time due to the viscous effects in the material.