Question: The relation that describes an instability of an interface between two fluids of different densities which occurs when the lighter fluid is pushing the heavier fluid is named after which British physicist who passed away in 1975?
Sentence (from "Preferential concentration"): The extent by which particles cluster is determined by the Stokes number, defined as formula_1, where formula_2 and formula_3 are the timescales for the particle and fluid respectively; note that formula_4 and formula_5 are the mass densities of the fluid and the particle, respectively, formula_6 is the kinematic viscosity of the fluid, and formula_7 is the kinetic energy dissipation rate of the turbulence.
Relevant evidence: No