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The dynamics and stability of extragalactic jets may be strongly influenced by small (and probable) differences in pressure between the jet and the ambient and within the jet itself. The former give rise to expansion and recollimation of…
We study the destabilization of a round liquid jet by a fast annular gas stream. We measure the frequency of the shear instability waves for several geometries and air/water velocities. We then carry out a linear stability analysis, and…
Hydrodynamic instabilities often cause spatio-temporal pattern formations and transitions between them. We investigate a model experimental system, a density oscillator, where the bifurcation from a resting state to an oscillatory state is…
The interfacial instability in a two-phase mixing layers between parallel gas and liquid streams is important to two-phase atomization. Depending on the inflow conditions and fluid properties, interfacial instability can be convective or…
A wide range of natural and engineered fluid flows exhibit spatial or temporal viscosity variations, spanning scales from microbial locomotion to planetary mantle convection. These variations introduce qualitatively new physical mechanisms…
We report spontaneous oscillations of circular hydraulic jumps created by the impact of a submillimeter water jet on a solid disk. The jet flow rate is shown to condition the occurrence of the oscillations while their period is independent…
We investigate the properties of forced inertial modes of a rotating fluid inside a spherical shell. Our forcing is tidal like, but its main property is that it is on the large scales. Our solutions first confirm some analytical results…
The laminar flow past rectangular prisms is studied in the space of length-to-height ratio ($1 \le L/H \le 5$), width-to-height ratio ($1.2 \le W/H \le 5$) and Reynolds number ($Re \lessapprox 700$). The primary bifurcation is investigated…
The Surface Green Function Matching analysis (SGFM) is used to study the normal modes of the interface oscillations between two non-mixed fluids by considering the difference in their densities and viscosities. The limiting case of…
The present study aims to investigate the role of injector geometry, particularly injector tube length to diameter ratio (L/D) in liquid jet stability and breakup in presence of crossflow. Water is injected into a crossflow of air.…
This fluid dynamics video describes droplet impingement experiments performed on superhydrophobic surfaces. When droplets of pure water are impinged upon superhydrophobic surfaces, a region of thin coherent jets are observed for Weber…
The paper presents the results of a theoretical study of the noise shielding effect of a subsonic turbulent jet located near a rigid screen. The developed theoretical model, based on the methods of the Geometrical Theory of Diffraction…
Relativistic jets in Galactic superluminals and extragalactic AGN may be surrounded by a wind near to the central engine. Theoretical analysis and numerical simulation reveal considerable stabilization of relativistic jet flow by a wind to…
This study concerns a turbulent jet at Mach number $M_j=0.9$, subject to a uniform external flow stream at $M_f=0.15$. We assess the mechanisms that underpin the reduction in fluctuation energy that is known to occur when a jet is…
We explore the laminar to turbulence transition of round jets at low Reynolds number (Re < 1000) using a novel experimental setup and linear stability theory (LST). The setup has a large domain and a low disturbance environment which…
We present Space Telescope Imaging Spectrograph (STIS) spectral images of the HH~30 stellar jet taken through a wide slit over two epochs. The jet is unresolved spectrally, so the observations produce emission-line images for each line in…
We have investigated the influence of velocity shear and a radial density profile on the spatial development of the current driven kink instability along helically magnetized relativistic jets via three-dimensional relativistic…
One of the most prominent dynamical features of turbulent, rapidly-rotating convection is the formation of large-scale coherent structures, driven by Reynolds stresses resulting from the small-scale convective flows. In spherical geometry,…
Comparisons studies between simulated variable density turbulent flows often consist of direct graphical representations where the level of agreement is determined by eye. This work demonstrates a formal validation methodology using an…
Glycerol is a hygroscopic fluid that spontaneously absorbs water vapor from the atmosphere. For applications involving glycerol, care must be taken to avoid exposure to humidity, since its viscosity decreases quickly as water is absorbed.…