If we have a body traveling through a foam or fizz, then how does one measure mach-number or reynolds-number in a foamy/fizzy medium? What are the mechanics under this regime? Presumably, a foam or fizz is not a true static homogenous fluid medium. Perhaps for simplicity, we could assume that the foam is isotropic at macroscopic scales. So your interaction with the foam is the same, regardless of which direction you're traveling through it. A swimmer in the water can propel himself forward by paddling/pushing off that water. Would they be able to do the same thing if they were in a pool of foam/fizz? I'd read that if large deposits of methane hydrate at the bottom of the sea erupt, then immense columns of gas bubbles can stream to the surface, and that if some hapless ship were caught in them, then it would lose buoyancy and sink to the bottom. Such phenomena have been posited as explanations for disappearances of ships in the Bermuda Triangle. So a foam composed of liquid-vapor phases offers less support than a medium of the pure liquid phase would. But obviously foam must offer more support/resistance than the pure vapor phase would, since such foams have been used to decelerate hurtling objects and dissipate their kinetic energy. So is a foam the kind of medium that can only offer some limited resistance, and not something you can also push off of? What is the fastest way to collapse a fluid foam?