相关论文: Thrust Generation by Shark Denticles
The meter-size barrier in protoplanetary disks is a major challenge in planet formation, for which many solutions were suggested. One of the leading solutions is dust traps, that halt or slow the inward migration of dust particles. The…
In undulatory swimming of fish, muscles contract sequentially along the body to generate a bending wave that pushes against the water and produces thrust. Here, we use a 3D computational fluid dynamics model coupled to the motion of the…
We analyse the concentration of solid particles in vortices created and sustained by radial buoyancy in protoplanetary disks, i.e. baroclinic vortex growth. Besides the gas drag acting on particles we also allow for back-reaction from dust…
Flapping-based propulsive systems rely on fluid-structure interactions to produce thrust. At intermediate and high Reynolds numbers, vortex formation and organization in the wake of such systems are crucial for the generation of a…
Recently there have been significant interests in the spin hydrodynamic generation phenomenon from multiple disciplines of physics. Such phenomenon arises from global polarization effect of microscopic spin by macroscopic fluid rotation and…
Dense particulate suspensions can not only increase their viscosity and shear thicken under external forcing, but also jam into a solid-like state that is fully reversible when the force is removed. An impact on the surface of a dense…
For nearly a century, researchers have tried to understand the swimming of aquatic animals in terms of a balance between the forward thrust from swimming movements and drag on the body. Prior approaches have failed to provide a separation…
Partial dust obscuration in active galactic nuclei (AGN) has been proposed as a potential explanation for some cases of AGN variability. The dust-gas mixture present in AGN tori is accelerated by radiation pressure, leading to the launching…
Toroidal vortex, a topological structure commonly observed in nature, exist in various types such as bubbles produced by dolphins and the air flow surrounding a flying dandelion. A toroidal vortex corresponds to a spatiotemporal wave packet…
A rigorous theory for the generation of a large-scale magnetic field by random non-helically forced motions of a conducting fluid combined with a linear shear is presented in the analytically tractable limit of low Rm and weak shear. The…
Large sea spray drops - of up to 2mm in diameter - constitute one of the most uncertain factors controlling the intensification of hurricanes and severe storms because their generation mechanisms are not understood. Wave splashing produces…
We study the dynamics of galaxy mergers, with emphasis on the gas feeding of nuclear regions, using a suite of hydrodynamical simulations of galaxy encounters. The high spatial and temporal resolution of the simulations allows us to not…
Galactic collisions trigger a number of phenomena, such as transportation inward of gas from distances of up to kiloparsecs from the center of a galaxy to the nuclear region, fuelling a central starburst or nuclear activity. The inverse…
The formation of planetesimals from cm-sized pebbles in protoplanetary disks faces significant barriers, including fragmentation and radial drift. We identify a previously unaccounted screening force, arising from mutual shielding of…
After a star has been tidally disrupted by a black hole, the debris forms an elongated stream. We start by studying the evolution of this gas before its bound part returns to the original stellar pericenter. While the axial motion is…
White dwarf (WD) pollution is thought to arise from the tidal disruption of planetary bodies. The initial fragment stream is extremely eccentric, while observational evidence suggest that discs are circular or nearly so. Here we propose a…
Organisms often swim through density stratified fluids. In this Letter, we investigate the dynamics of small active particles swimming in density gradients and report theoretical evidence of taxis as a result of density stratification…
The "reverse-dynamo" mechanism - the amplification/generation of fast plasma flows by micro scale (turbulent) magnetic fields via magneto-fluid coupling is recognized and explored. It is shown that macro-scale magnetic fields and flows are…
The generation of stress in a pore due to salt crystallization is generally analysed as a compressive stress generation mechanism using the concept of crystallization pressure. We report on a completely different stress generation…
Sea ripples are small-scale bedforms which originate from the interaction of an oscillatory flow with an erodible sand bed. The phenomenon of sea ripple formation is investigated by means of direct numerical simulation in which the sediment…