We consider the fluid dynamics of the chocolate fountain. Molten chocolate is a mildly
shear-thinning non-Newtonian fluid. Dividing the flow into three main domains—the pumped flow up the
centre, the film flow over each dome, and the freely falling curtain flow between the domes—we
generate a wide-ranging study of Newtonian and non-Newtonian fluid mechanics. The central pumped
flow is a benchmark to elucidate the effects of shear-thinning. The dome flow can be modelled as a
thin-film flow with the leading-order effects being a simple balance of gravity and viscosity.
Finally, the curtain flow is analytically intractable but is related to the existing theory of water
bells (both inviscid and viscous). In pipe flow, Newtonian fluids exhibit a parabolic velocity
profile; shear-thinning makes the profile more blunted. In thin-film flow over the dome,
gravitational and viscous effects balance and the dome shape is not important beyond the local
slope. We find that the chocolate thins…