It's really cool how a Mach number emerges from traffic flow, with speed of cars vs speed of information, completely with shock waves and everything!
https://en.wikipedia.org/wiki/Burgers%27_equation
This equation was initially thought of as the appropriate continuous version of the discrete problem investigated by Fermi-Pasta-Ulam-Tsingou (on a very early digital computer shortly before Fermi's death), but then it was realized the KdV equation was better for that.
https://en.wikipedia.org/wiki/Fermi%E2%80%93Pasta%E2%80%93Ul...
https://en.wikipedia.org/wiki/Korteweg%E2%80%93De_Vries_equa...
Intro to Traffic Flow Modeling and Intelligent Transport Systems
(Note that thanks to aggressive monetisation of MOOCs they shut off access to the course a few weeks after you enrol in it.)
https://www.edx.org/course/intro-to-traffic-flow-modeling-an...