The collapse of a vapor bubble in a corner generates a jet whose direction depends on the corner opening angle and bubble position. Experimental data is found to agree well with a potential flow model that gives analytical solutions for a family of corner opening angles.

The process of blister-actuated laser-induced forward transfer (BA-LIFT) results in focused jets which are thinner and faster than regular jets.

Numerical simulations of isotropic turbulence find that the energy spectrum in the dissipation range cannot be described by a single exponential for R${}_{\lambda }$>20, and that this effect is associated with intermittent energy transfer.

Experimental observations of the pair correlation function of small inertial particles in a turbulent flow of dilute polymer solutions shows that particle clustering increases with the concentration of polymers, possibly reflecting a reduction of vorticity relative to straining.

An investigation of the behavior of self-propelled particles in complex media finds a transition from thermal diffusion to collision-driven diffusion as the particle area fraction is increased. Collisions with passive particles increases the rotational diffusion of the self-propelled particles, leading to their “self-trapping.”

The general parametric solution for the steady unidirectional flow of a thin rivulet of a generalized Newtonian fluid is obtained and illustrated for Carreau and Ellis fluids. In particular, the solution is used to describe the behavior of a rivulet of a strongly shear-thinning Ellis fluid.

The effects of wall thermal conditions on the canonical case of an impinging shock wave interacting with a turbulent boundary layer is an under-explored topic. Direct numerical simulations are used to study the flow properties of supersonic shock/boundary-layer interactions with distinct wall thermal conditions and shock angles.

An investigation of both the large- and small-scale flow properties of moist and cloudy, turbulent Rayleigh-Bénard convection suggests that the large scale circulation is insensitive to phase composition/interfacial physics; rather, it depends only on the strength of the turbulence.

A mechanism for rapidly achieving thermal relaxation in high-$Pe$ convective simulations is studied in the context of Rayleigh-Bénard convection. It achieves statistically similar states to standard timestepping and saves up to an order of magnitude in computational time for the problems studied.

Liquid sheet fragmentation is ubiquitous in nature and may shape phenomena such as the rain-induced propagation of foliar diseases. An experimental study investigates the formation and fragmentation of an asymmetric liquid sheet upon impact of a drop close to the edge of a solid substrate.

Factors governing atomization of droplets impacting a mesh, starting with the elementary unit of a single hole, are investigated. It is shown how this process can be used to generate finely controlled sprays with micrometric droplet sizes and low kinetic energy, as is critical for agricultural applications.

The effect of finite magnetic Reynolds numbers ($Rm\sim {10}^2$) on MHD flow in a square duct was studied using direct numerical simulations. The structure of the secondary mean flow is modified significantly and the streamwise anisotropy is strongly enhanced away from the boundary layers.

To investigate how chemical dispersant impacts the transport of oil slicks such as the one from the Deepwater Horizon, a multiscale large-eddy simulation approach is used to show that the breakup of the oil slick into small droplets changes the mean transport direction and horizontal spread of the oil plume.

When a dog accelerates its tongue to lap water, a water column is created and pinches off close to the tongue. Physical experiments and a theoretical model of accelerating a solid sphere from a liquid bath elucidate the mechanism of the liquid-column formation and pinch-off.

Wetting over liquid films governs important phenomena but is poorly understood. A water front moving over a micrometer-thick film of silicone oil on a solid surface is imaged. Capillary suction in the meniscus induces thinning of the oil film and a wavelike film profile with local backflows.

Exponential thinning of a viscoelastic filament is analyzed using the Onsager variational principle.

The Rayleigh-Taylor instability of a thin viscous film coating the inside of a spherical substrate is studied. The instability properties are investigated by performing a linear optimal transient growth analysis. The pattern formation is further analyzed using nonlinear numerical simulations.

A solid sphere translating tangent to an elastic membrane is subject to a lift force perpendicular to its direction of motion. This effect is attributed to an elastohydrodynamic coupling that arises from the breaking of flow reversal symmetry induced by elastic deformation.

We theoretically and numerically study the effects of a uniform magnetic field on the dynamics of ellipsoidal ferromagnetic and paramagnetic particles in a simple shear flow at low Reynolds number. With numerical simulations we further illustrate their lateral migration in wall-bounded shear flows.

An original mathematical tool suitable for describing fluid dynamics in micropumps induced by transverse forced vibrations of an elastic beam is presented. The model could also be used in designing engineering software for micromachinery applications.

A reinforcement learning algorithm is applied to find quasi-optimal policies for buoyancy control of inertial probes/particles in order to avoid trapping and to reach specific regions when navigating in complex two- and three-dimensional flows.

Liquid-vapor phase change is simulated in a porous medium, using a diffuse-interface model and the van der Waals equation of state. The role of wettability and pore space geometry on phase separation and on the propagation of evaporation fronts is investigated.

The drag experienced by a spherical intruder settling through a medium composed of transparent granular hydrogels and water is measured as a function of its speed and depth. Internal visualization of the medium shows its flow to be localized around the advancing intruder.

The preferential concentration of inertial particles in isotropic turbulence is studied using wavelets, enabling the joint scale-space analysis of the flow field of the carrier phase, the concentration field of the dispersed phase, and interphase conditioned statistics.

Resolved simulations of turbulent flow past a fixed planar array of cold particles show the fundamental differences between velocity and temperature fields, cast light on the limitations of the point particle model and illustrate the mechanism by which turbulence disrupts the thermal wakes.

It is shown that the geometric state of fluids within porous media can be expressed in terms of a relationship that links the fluid volume, surface area, mean curvature, and Euler characteristic. The relationship is able to accurately model complex changes in fluid connectivity and structure.

Multifluid flows with changes in the topology of the interface separating the different fluids, in a turbulent vertical channel, are examined using direct numerical simulations. The results show how different surface tension changes the evolution of the flow and the interface topology.

The physics of turbulent flow in porous media is explored in the Lagrangian frame. The evolution of curvature angles along the fluid trajectories reveals the multiscale nature of turbulence. The asymptotic value of the curvature angle quantifies the effect of geometric confinement on turbulence.

Fractal impellers can lead to a considerably shorter mixing time compared to regular impellers. This is explained by the differences in characteristics of flow and scalar fields. Moreover, a mathematical model is proposed which can approximate the decay rate of the passive scalar fluctuations.

The dispersion coefficient of a passive solute into a pulsatile electroosmotic flow with slippage at the microcapillary wall is derived. We found that the slip condition can enhance the dispersion coefficient by up to two orders of magnitude over the no-slip condition.

Scale locality of the energy cascade is demonstrated using direct numerical simulations data of homogeneous isotropic turbulence with Taylor microscale Reynolds numbers ranging from 37 to 1131. The range of influential scales for this scale locality is found to be independent of Reynolds number.

Time development (from top to bottom) of vortical structures (in red) in background of low vorticity (blue) in planar cross-sections of turbulence subjected to magnetic field on an elongated domain of aspect ratio 8, at $16384\times {2048}^2$ grid resolution.

The effects of the ambiguity in the definition of the Reynolds stresses to the coherent structures in wall turbulence are studied. It is confirmed that sweeps, ejections, and rollers are robust features of the flow.

Implementation of a bypass laminar-to-turbulent transition is explored. We show that our method, by bypassing linear exponential growth, can induce high mixing capacity localized turbulence in a laminar channel flow at low $Re$. An on-demand mixing enhancement in laminar channel flow is proposed.

Aggregation and fragmentation are frequently observed in industrial and natural systems. In an experimental study, an initially large aggregate of magnetic particles is broken by the turbulent fluctuations of a flow. The size of the resulting clusters is measured using three-dimensional reconstruction.

Turbulence forcing techniques are often required in the numerical simulation of turbulent flows. A novel forcing technique, based on physics, is devised to reproduce the centerline turbulent characteristics of round jets in a triply periodic box.

In a new study, the critical Reynolds number for the emergence of outer motions in turbulent channel flows is determined to be Re${}_{\tau }\approx 110$. The growing significance of outer motions is obtained by subtracting the inner contributions from the total at low to moderate Reynolds numbers.

An investigation of the interaction of a vortex ring colliding with a coaxially aligned aperture, which extends the classical problem of a vortex ring impacting a solid wall, examines the behaviors of near-wall vortices in the proximity of a structural discontinuity (aperture tip).