Fibers in suspension migrate towards the center of the pipe where they are more aligned with the flow. The migration depends on the fraction of the volume of the suspension swept out by the rotating fibers.

Experimental evidence is presented for the existence of critical layers in inertioelastic shear flows over wavy surfaces, where theory predicts amplification of the spanwise vorticity.

Scaling laws are proposed for the size and the velocity of the droplet which is ejected when a bubble rises to a free surface and bursts. These new scalings consistently incorporate the effect of gravity and the limit of negligible viscosity of the liquid.

The Stuart-Landau reduced order model is tested with experimental data from the wake of a cylinder wake forced by plasma actuators, finding an important role played by the changing mean flow.

Inertial breakup modes are identified at microscale for co-flowing jets using a high-pressure mixer.

Three-dimensional direct numerical simulations of Rayleigh-Taylor turbulence with various initial unstable temperature distributions finds a modified self-similar mixing in the long term.

Flow transitions in wormlike micelle solutions flowing around a microfluidic 90° bend are studied. Shear-banding properties of the solution correlate with the form of secondary flow, while the micelle morphology (linear vs branched) has little effect on the flow behavior.

Two-dimensional numerical simulations of a suspension of sedimenting particles in a Bingham fluid find three possible regimes: all, a fraction, and none of the particles sedimenting.

A normal compressive shock with upstream pressure from 10 to 500 bar is analyzed for density, enthalpy, entropy, and velocity with nitrogen, oxygen, argon, and carbon dioxide. New descriptions for sound speed, Prandtl’s relation, the Rankine-Hugoniot relation, and Riemann invariants are presented.

Thermal convection in the spherical gap geometry induced by dielectric heating is studied by means of an extended thermoelectric hydrodynamics model. Numerical simulations based on this model are validated on the ISS experiment GeoFlow.

During sedimentation in a miscible, viscous liquid, polymeric drops self-assemble into a toroidal-spiral structure, which can be solidified by photoinitiated cross-linking. With a suitable arrangement three drops can be encapsulated, possibly enabling controlled release of a therapeutic drug cocktail.

When a drop impacts a stationary drop on a non-wetting surface, the two drops coalesce, spread on the surface and retract, sometimes bouncing off. We measure the maximum diameter and retraction time for a wide range of parameter values and generalize known single drop models to drop-on-drop impacts.

The collisions of a drop stream with an immiscible jet are experimentally studied revealing the formation of several complex structures classified in four main regimes. When neither the drops nor the jet fragment,“drops in jet” are observed that could be hardened to produce advanced fibers.

To understand why the magnetic fields of many planets are axial dipoles, the evolution in time of a seed magnetic field is studied using a dynamo model. The field is shown to excite helical convection, and the timescale for the growth in convection matches that for dipole formation.

A new model of wind farm aerodynamics establishes an upper bound for power density, which is an order of magnitude larger than achieved by contemporary turbine arrays. The model also provides a one-equation prediction for the output of existing wind farms, and can include atmospheric stability.

An investigation shows that laminar supersonic flow on a 2D compression corner can destabilize to become 3D beyond a critical turn angle. This compressible instability resides in the recirculating flow, producing spiral wall flow patterns postseparation and wall temperature streaks downstream.

Viscous fingering arises as air invades a draining viscous suspension. Experiments show that suspended particles delay the onset of fingering but also accelerate its growth rate. In addition, particles of select sizes are observed to coat the channel surfaces and not drain.

We simulate a fluid droplet with suspended particles rising in another fluid with a diffuse interface model in which phase boundaries are replaced with smooth spreading interfaces. We find that at low Reynolds number the droplet terminal velocity decreases exponentially with particle concentration.

A new analysis shows that the force required to maintain the relative movement of parallel plates is significantly reduced when these plates are heated in a spatially nonuniform manner.

Simple model microswimmers in an oriented uniaxially anisotropic fluid, such as a nematic liquid crystal, can show rich alignment behavior due to purely hydrodynamic effects. The type of propulsion mechanism and the relative magnitudes of the different involved viscosities play a crucial role.

In microfluidic devices, inertia drives particles to focus on a streamline and form one-dimensional microfluidic crystals. Asymptotic theory for the pairwise particle interactions shows that particles assemble into stable equilibria, and the dynamics are analogous to the motion of a damped spring.

At large Knudsen numbers a Janus particle in a thermal gradient shows a preferred orientation. The interplay between rotational diffusion and thermophoretic motion is investigated.

We perform fully resolved simulations of expansion waves propagating into particle beds of varying volume fractions using the discontinuous Galerkin spectral element method. We validate state-of-the-art drag models and predict the final state of the particle bed using isentropic flow relations.

A numerical investigation shows that finite-size Lagrangian coherent structures result from bulk transport near Kolmogorov-Arnold-Moser tori and a dissipative effect that finite-size particles experience near the free surface.

We propose corrections to the kinetic theory for fluidity in granular flows near random close packing, in order to take account of anisotropy and increases in granular temperature.

Particles differing in size or density segregate in dense granular flows. In bidisperse mixtures, the sinking (small or heavy) species concentration that maximizes the segregation flux is $<50\%$ and decreases with increasing size or density ratio, matching a classic kinetic-sieving model.

An idealized first-principles model describing filtration of a feed solution containing small particles in a microstructured porous membrane is presented. Optimal configurations for the pore microstructure are identified in terms of maximizing throughput of filtered fluid and filter lifetime.

Intermittency of quasiclassical quantum turbulence in superfluid ${}^4$He is experimentally found to be temperature dependent and enhanced for a range of temperatures compared to classical turbulence, in contrast with nearly flow-independent intermittency of turbulence in classical fluids.

A new forcing method for generating statistically stationary scalar fields in incompressible turbulence is proposed based on an analogy with chemical reactions.

An investigation of the statistics of incremental averages of passive scalar fluctuations shows that, unlike statistics of their differences, they inherit information from the scalar field’s large scales, for averages over all increment sizes, and can differ from analogous statistics for the velocity field.

A study of how the interplay between mechanical and buoyant production of turbulent kinetic energy affects fully developed atmospheric turbulent flows finds impacts both on the frequency of extreme scalar fluctuations and on the time-directional properties of scalar Eulerian measurements.

Turbulent-nonturbulent interfaces are studied in temporally evolving subsonic and supersonic turbulent boundary layers by comparing the results of direct numerical simulations with the entrainment model based on a single vortex and the theory for spatially evolving boundary layers.

We analyze kinetic energy (KE) transport allowing wind speed recovery behind a row of wind turbines, showing that KE replenishment is significant after about the 6th row. Before that there is net negative transport out of the turbine layer, and initial advection of KE is the main energy source.

Direct numerical simulations of turbulent pipe flow of power-law fluids show that the effect of shear thinning on turbulence statistics in the inner-wall region does not disappear as Re is increased. A log-law mean viscosity profile is also predicted that is self-similar in the inner region.

Properly accounting for the intricate Prandtl number dependence in different layers of turbulent channel flows, a multiscaling analysis is developed for the mean thermal energy balance (MHB) equations. A formal analogy is established between the MHB equation and the mean momentum balance equation.

The formation number of confined vortex rings is studied using direct numerical simulations. The structure of the vortex ring at pinch-off depends on the injection program and the confinement ratio. The value of the formation time is predicted using a model for the viscous confined vortex ring.

A dynamic meniscus affects viscous dissipation of oscillating contact lines. A theoretical proposal, marrying viscous sloshing dynamics and a realistic contact line model including contact angle hysteresis, finds that both the wave damping rate and frequency increase at small amplitude.

Two-dimensional turbulence can generate shallow water waves. These waves carry information about the structure of their turbulent source. A theoretical calculation of the wave spectrum is proposed, which may lead to an insightful way to characterize turbulence.

In an experimental investigation, water surface waves are focused at the Huygens’ cusp of a parabolic wave maker. Small amplitude waves behave linearly and similarly to light waves, following the diffraction laws. Large amplitude nonlinear waves are distorted by a large scale flow and focus before the expected cusp.

The wake behind a concave, curved cylinder configuration is investigated at different Reynolds numbers. Distinctly different wake flow regimes were observed in the computed flow field, including oblique vortex shedding and dislocations. The crucial influence of a straight vertical extension is explored.

The effect of confinement in a high-aspect-ratio channel on the statistical properties of weak turbulence of gravity-capillary waves at the surface of water is investigated. Discreteness due to confinement coexists with an almost one-dimensional kinetic sort of wave turbulence.