Direct numerical simulations of the evolution of an interface separating less dense, clear salt water above from more dense, sediment-laden fresh water below, reveal that the destabilizing effects of double-diffusion and particle settling amplify each other above the diffusive interface, and tend to cancel each other below it.

The phenomenon of vortex ring pinch-off is quantified by the formation number and its connection to the pressure in the shear layer feeding the vortex ring as it develops. Researchers find that the formation of a high-pressure region behind the vortex ring is a necessary but not sufficient condition for pinch-off, and they offer a method for estimating pinch-off by tracking the development of this high-pressure region.

The dynamics of adhesion and detachment of capsules is studied using scaling theories and a simulation technique that couples the nonhydrodynamic surface forces, membrane mechanics, and Stokes flow, and the results are contrasted against vesicles’ behavior.

A theoretical analysis shows that polymers interacting with particles in a shear flow experience enhanced streamwise stretch that grows in amplitude and spatial extent with increasing Deborah number. This results in shear thickening of the viscosity and first normal stress coefficient of a particle suspension in a Boger fluid.

A theoretical study indicates that large-scale waves within the ocean can travel through “staircases” of water density, a motion that could enhance ice melting at the surface.

An investigation of the droplet impact of a non-Newtonian, shear-thickening liquid such as a cornstarch suspension reveals a freezing-like behavior at impact, following by a gentle and slow spreading, very different behavior from a Newtonian liquid. Identifying the dissipative mechanisms in such a droplet allows this counterintuitive behavior to be modeled and understood.

Evaporation of liquid on a hot solid causes droplets to levitate and self-propel, drawn by the underlying flow of vapor. Forcing an anisotropic flow of vapor using a herringbone pattern on a solid surface provides a simple geometry, allowing clarification of the underlying propulsion mechanism.

Experiments and simulations reveal that drops of highly viscous glycerol demonstrate a spectacular prompt tumbling rebound on sublimating slopes, bouncing like solid rocks while remaining in the liquid state, and rebounding much faster than low-viscosity liquid drops.

The spreading of sessile drops in miscible environments have distinctly different shape evolution and power law dynamics than sessile drops that spread in immiscible environments.

A hot sphere creates a viscosity variation that couples to the sphere’s motion. A method for finding the leading order force and torque acting on the sphere for any thermal distribution is presented, showing, in particular, that rotation and translation are coupled for a thermal dipole (Janus sphere).

Researchers demonstrate that the lifetime of an individual droplet embedded in a dense spray lamellae is much longer than that of a single drop evaporating in quiescent air, as described by the $d^2$ law. An analogy is made with the way mixing times are understood for passive scalars in order to describe the lifetime of dense spray lamellae stretched in a dry environment.

A Green’s-function-based method for computing the instantaneous velocity, pressure, and baroclinic energy flux strictly from measurements of the density perturbation field represents an important improvement with respect to existing techniques. Energy flux measurements are vital to interpreting the contribution of internal waves to the ocean’s energy budget.

A formal theory of scale interaction is presented. It links the superposition coefficient and the mean profile, explains why the log-law coefficients can depend on Re even though the log law itself is a Re-independent asymptotics, promises a method of interpolation to high Re, and more.