Mathematics isn't what is happening, though that's one of the best tools we have for describing it. I don't know of an actual scientific name for it.
T ake the formation of a crystal.
It begins small, around some seed, and proceeds at an increasing speed as the crystallization fringe expands, first more and then less rapidly, until it approaches its natural limit. Then there's a crystal, a new steady state, the result of a swelling and waning pattern of history dependent events, a flow. This same general acceleration and climaxing sequence is evident in complex successions of innumerable kinds, and may be present in change universally. It's a strictly local process and strictly locally originating process. T hese chains of events follow a strict sequence, with speeding up and then slowing down.