It's a really interesting question, I would love it if someone who understands this kind of physics properly would chime in!
By my understanding of Reynolds number etc, the faster they go, the more turbulent the flow, so the rocks would be constantly hitting against each other sideways, and surely grind to dust in the constantly accelerating scenario.
But maybe the infinite (looped) nature of this 'dimension' means that this logic doesn't apply. What would even be the 'characteristic length'? Are we thinking about established flow at the centre of an infinitely wide pipe? Am I wrong to think of constantly accelerating rocks with air in between as a type of fluid flow?