A minimal continuum model for active fluids exhibits turbulence as well as a dynamic hexagonal vortex lattice state, which is preceded by an extended turbulent transient.

Experiments with a complex fluid in an oscillating atomic force microscope find that the wall slip is well characterised by a real Navier interfacial friction coefficient instead of the usual slip height.

Janus-like rods which can be externally switched between straight, U, and S shapes give the possibility of steering individual rods within a group through a complex geometry.

Numerical simulations of dense granular flows in three different planar geometries find that the $\mu$-I scaling for the local viscosity is found to be valid for each geometry, but the data for the three geometries do not collapse to a single curve.

In direct numerical simulations of a turbulent jet, propagating helical waves which contain much of the energy are tracked from the near to the far field in order to find their scaling properties and dispersion laws.

With numerical methods and analysis of existing experimental results we show that combustion instability in a backward-facing step combustor can be maintained either with weak coupling between acoustic and hydrodynamic modes (semi-open loop) or with strong coupling (fully closed loop).

Elastic flow instabilities in the wake of a flexible cylinder can drive the motion of the cylinder, resulting in 1D and 2D oscillations. The time variation of the flow field and the state of stress in the fluid are shown using particle image tracking and flow-induced birefringence images.

Immersed boundary simulations are used to study settling in dispersions of sticky colloids and to develop an empirical model for the settling rate that is in good agreement with experiments. The model is applied to characterize attractive interactions in concentrated macromolecular solutions.

Orientation dynamics of graphene suspensions is investigated in oscillatory shear flow via flow dichroism. To evaluate whether graphene sheets behave as flexible or rigid sheets during flow, the experimental data are compared with predictions from a single particle Smoluchowski equation for spheroids.

Particle tracking velocimetry is applied to thermal counterflow in superfluid helium (He II), and the first method for separately analyzing the normal fluid and quantized vortex tangle velocities is presented, opening the door to new quantitative measurements of quantum turbulence.

The slip boundary conditions for the compressible Navier-Stokes equations for a polyatomic gas are derived from kinetic theory using the ellipsoidal statistical model of the Boltzmann equation. The slip coefficients for some typical polyatomic gases are presented explicitly.

A high-speed method for time-resolved measurements of wall shear rates providing microscopic resolution is presented. The wall shear rates produced by a single, collapsing cavitation bubble are studied.

At atmospheric pressure, a droplet impacting on a surface produces a splash. Reducing the ambient pressure suppresses this splash. The pressure effect is not well understood and this is the first study to present an in-depth comparison between various theoretical splashing models and simulations.

Particle image velocimetry of ionic wind produced by a positive dc corona in air is used to evaluate lift force, and results are consistent with a general theoretical expression previously found for net momentum transfer. Momentum transfer efficiency is found to be sensitive to the electrode aerodynamic wake and the electric field orientation.

We report an inertial instability in electro-osmotically driven periodic channel flows. The instability sets in at Reynolds numbers around 20 and leads to a plug-like mean flow along the channel.

A numerical study shows that an electrically conducting fluid driven by a traveling magnetic field always exhibits a Joule dissipation larger than the viscous one. This surprising result suggests the existence of an upper bound for the efficiency of electromagnetic pumps, which can’t exceed 50%.

A theoretical model predicts forward blood spatter from a 9-mm bullet and favorably agrees with experimental data. Blood drop generation is explained through chaotic liquid disintegration built in the framework of percolation theory.

Combined static and alternating magnetic fields are shown to create an oscillating pressure that can cause cavitation in molten metals. A time-averaged flow is also excited, consisting of two tori squeezed to thin boundary layers. Flow instability develops as a standing wave between these tori.

Driving a planar thin film of a compressible viscous fluid using random surface forcing leads to remarkable fluctuation-induced stresses on the bounding surfaces of the film, exhibiting power-law, or even non-decaying, behaviors as a function of the film thickness.

We investigate how an initially uniform distribution of small inertial particles evolves due to transport by turbulent channel flow. Concentration fluctuations grow as particles approach a multifractal attractor with strong dependence on the distance to the wall which can be faster than exponential.

Trajectories of N-sided polygons falling in quiescent media are used to measure the edge effect on the descent. A new length scale is proposed to estimate the equivalent dimensionless numbers. This allows use of the original phase diagram for disks and reconciles the effects of particle shape.

With the Euler-Lagrangian coupled method we simulate homogeneous nucleation cavitation induced by shock reflection in a microchannel. Nucleation is found to occur in three stages: energy deposition, generation, and growth. Initial generation time is not found to depend strongly on shock intensity.

A fully compressible three-phase cavitation model is developed to study the interaction between the cavitation and primary atomization. The simulations reveal that the developing cavitation condition with cyclic air entrainment is the most favourable condition for primary atomization.

The collapse of a granular column in a fluid shows that both the dynamics and the deposit shape depend on the aspect ratio, Stokes number, and grain-fluid density ratio. Classification of flow regimes and characterization of the associated dynamics are proposed through an experimental investigation.

A continuum granular model is used to investigate dust dispersion and segregation behind a moving shock in a polydispersed system. The results indicate that larger and heavier particles are more dispersed than smaller and lighter ones. The reasons are discussed in terms of the governing forces.

We calculate, by numerical simulation of a Langevin equation, how the intrinsic viscosity of a dilute suspension of small (triaxial) ellipsoids depends on the degree to which triaxiality is broken. We find that the intrinsic viscosity decreases as the shape becomes less axisymmetric.

Experiments find that rogue wave events for Faraday waves tend to be preceded one period before by a surrounding waveform of high angular average and small variation of wave height.

A large eddy simulation is used to study the surface patterns of noninertial passive buoyant particles in the ocean mixed layer. A mechanism for preferential concentration that is independent of inertial effects is then identified and quantified as a function of the terminal rise velocity.

Results of a high-fidelity large eddy simulation are used to compute the far-field sound that results from the unsteady loading of a propeller operating at design condition. High levels of unsteadiness at the blade tip account for the majority of far-field sound.

Two-dimensional flow is often approximated by driving thin fluid layers electromagnetically. By comparing three common experimental configurations, it is shown that the single-layer and immiscible configurations minimize out-of-plane flow over a wider range of Reynolds numbers than miscible configurations.

A study combining spectral filtering and numerical simulations at enhanced spatial and/or temporal resolution is used to clarify the proper scaling of dissipation and enstrophy in forced incompressible isotropic turbulence.

The dynamics of the helical vortex breakdown has revealed a Ruelle-Takens-Newhouse route to chaos coming from the nonlinear interactions of pure hydrodynamic modes. Global stability analysis, Fourier series decomposition, and time series analysis have been used to shed light on the dynamical states.

Crossed surface waves generate eddy currents near the fluid surface owing to hydrodynamic nonlinearity. We studied how these currents penetrate into the fluid bulk and showed that a thin compressible insoluble liquid film presented on the fluid surface increases their intensity.

A series of laboratory experiments were performed to study the Peregrine Breather evolution in a wave flume of finite depth and deep water. The experimental results are compared with computations based on both the nonlinear Schrödinger equation and the Dysthe equation, both with a dissipation term.