Critical behavior of drops in linear flows. I. Phenomenological theory for drop dynamics near critical stationary states

The dynamics of viscous drops in linear creeping flows are investigated near the critical flow strength at which stationary drop shapes cease to exist. According to our theory the near-critical behavior of drops is dominated by a single slow mode evolving on a time scale that diverges at the critical point with exponent 1/2. The theory is based on the assumption that the system undergoes a saddle-node bifurcation. The predictions have been verified by numerical simulations for drops in axisymmetric straining flow and in two-dimensional flows with less vorticity than in shear flow. Application of our theory to the accurate determination of critical parameters is discussed.