There is really not much to the physics of troughs. We use them every day to hold liquid. They include coffee mugs, soup bowls, sinks, and bathtubs.
Troughs truly become interesting when we try to make them less susceptible to slosh or we try to make them work in multiple directions (let's face it a coffee mug is boring and does not need engineer to design it).
For example, a tortuous path entrance to a trap can prevent the trap from spilling during low fill fraction horizontal handling. This entrance must prevent spilling in multiple directions and also must do this during an energetic transportation environment.
Unlike all other PMD components, troughs do not use surface tension to control liquid - they use the hydrostatics present during an acceleration and require this acceleration to work. The figure to the left shows a "tire" shaped trough capable of retaining propellant in any lateral direction. The pick up assembly illustrated obeys the physics of galleries.