The roughness of a solid is known to increase the minimal temperature for observing Leidenfrost effect. A new study shows that volatile liquid drop placed on surface smooth substrate---a non-volatile pool---reaches state as soon pool just hotter than boiling point, with no apparent threshold.

The conical shape of a shuttlecock allows it to flip on impact. As light and extended particle, flies with pure drag trajectory. We first study the phenomenon dynamics flight then discuss implications game. Lastly, possible classification different shots is proposed.

We study the trajectory of dense projectiles subjected to gravity and drag at large Reynolds number. show that two types trajectories can be observed: if initial velocity is smaller than terminal free fall, we observe classical Galilean parabola: it larger, projectile decelerates with an asymmetric first drawn by Tartaglia, which ends a nearly vertical as wall impeded movement. This regime often observed in sports, fireworks, watering, etc. its main characteristics.

We study the effect of gravity on giant soap bubbles and show that it becomes dominant above critical size [Formula: see text], where text] is mean thickness film capillary length ([Formula: stands for vapor-liquid surface tension, liquid density). first experimentally large do not retain a spherical shape but flatten when increasing their size. A theoretical model then developed to account this effect, predicting based mechanical equilibrium. In stark contrast drops, we there no limit...

The physical mechanisms that bring about the propulsion of a rotating helix in granular medium are considered. A propulsive motion along axis is induced by both symmetry breaking due to helical shape, and anisotropic frictional forces undergone all segments medium. Helix dynamics studied as function rotation speed its geometrical parameters. effect pressure applied external load were also investigated. theoretical model developed based on force experienced slender body moving material,...

Abstract Recent simulations and experiments have shown that shear-thickening of dense particle suspensions corresponds to a frictional transition. Based on this understanding, non-monotonic rheological laws been proposed successfully tested in rheometers. These recent advances offer unique opportunity for moving beyond rheometry tackling quantitatively hydrodynamic flows suspensions. Here, we investigate the flow suspension down an inclined plane show that, at large volume fractions, surface...

Several locomotion strategies are based on the anisotropic nature of forces experienced by moving body with its environment. We report experiments anisotropy frictional force a cylinder in granular medium as function orientation α between and velocity. The component direction parallel to velocity is always higher than perpendicular component; therefore, anisotropic. While increases continuously angle α, we observe that reaches maximum value for an αc≃35°. To rationalize these observations,...

Abstract Liquid rings can be generated in the Leidenfrost state using liquid oxygen of low boiling point ( $- 183~\textdegree \mathrm{C} $ ) and high magnetic susceptibility, allowing one to ‘sculpt’ into a ring shape an annular magnet. When field is turned off, shrinks back puddle with constant acceleration. A potential flow approach accurately describes dynamics closure equation reminiscent Rayleigh–Plesset for collapse transient cavities.

We investigate experimentally and theoretically the stability of a shear-thickening suspension flowing down an inclined plane. In previous paper (Darbois Texier et al. , Commun. Phys. vol. 3, 2020), we have shown that for particle volume fractions $\phi$ above discontinuous fraction $\phi _{DST}$ long surface waves grow spontaneously at flow Reynolds number much below 1. This motivated simplified analysis based on purely inertialess mechanism, called ‘Oobleck waves’ which couples negatively...

Liquid oxygen, which is paramagnetic, also undergoes Leidenfrost effect at room temperature. In this article, we first study the deformation of oxygen drops in a magnetic field and show that it can be described via an effective capillary length, includes force. second part, describe how these ultra-mobile passing above magnet significantly slow down even trapped. The critical velocity below drop captured determined from induced by field.

Non-cohesive materials such as sand, dry snow or cereals are encountered in various common circumstances, from everyday situations to industry. The process of digging into these remains a challenge most animals and machines. Within the animal kingdom, different strategies employed overcome this issue, including excavation methods used by ants, two-anchor strategy soft burrowers razor-clams, undulatory motions exhibited sandfish lizards. Despite development technology mimic techniques diggers...

In this paper the authors aim to explain spontaneous rotation of melting ice bodies floating on surface water. As liquid is cooled down by ice, elements fluid closest interface reach 4${}^{o}$C, point maximum density, and settle, creating a downward flow that results in vertical vortex sets body rotational motion. The recreate phenomenon successfully lab.

We study experimentally the dynamics of shuttlecocks. show that their trajectory is completely different from classical parabola: for a same launch, flight shuttlecock quickly curves downwards and almost reaches vertical asymptote. solve equation motion with gravity drag at high Reynolds number find an analytical expression range. At velocity, this reach does not depend on velocity anymore. This phenomenon, we call "aerodynamic wall", highly observable in badminton. Then how shape influences...

Zigzag paths in sports ball trajectories are exceptional events. They have been reported baseball (from where the word knuckleball comes from), volleyball and soccer. Such associated with intermittent breaking of lateral symmetry surrounding flow. The different scenarios proposed literature (such as effect seams baseball) first discussed compared to existing data. We then perform experiments on zigzag propose a new explanation based unsteady lift forces. In second step, we exploit wind...

Antibubbles are ephemeral objects composed of a liquid drop encapsulated by thin gas shell immersed in medium. When the is made volatile and medium superheated, inflates at rate governed evaporation flux from drop. This thermal process represents an alternate strategy for delaying antibubble collapse. We model dynamics such ``thermal'' antibubbles incorporating to film drainage equation heat-transfer-limited drop, which nourishes with vapor, as Leidenfrost drops. demonstrate that inflation...

The size of sports fields considerably varies from a few meters for table tennis to hundreds golf. We first show that this is mainly fixed by the range projectile, is, aerodynamic properties ball (mass, surface, drag coefficient) and its maximal velocity in game. This allows us propose general classifications played with ball.

We measure and analyze the drag force experienced by a rigid rod that penetrates vertically into granular medium partially withdraws before sinking again. The during successive reintrusions is observed to be significantly smaller than in first run. Two regimes are evidenced depending on how reintrusion depth compares with withdrawal distance $\mathrm{\ensuremath{\Delta}}$. These two characterized curve of positive negative curvature separated an inflection point, which experimentally....

We consider the penetration dynamics of a vertical cylinder into dry granular medium subjected to successive impacts. The depth impactor below free surface $z_N$ first evolves linearly with impact number $N$ and then follows power-law evolution $z_N \propto N^{1/3}$. reached by after given impacts is observed increase energy but decrease its diameter density medium. develop model that accounts for quasi-static inertial forces applying on rationalize our observations. This approach reveals...

Ice disks were released at the surface of a thermalised aluminium plate. The fusion ice creates lubrication film between disk and situation is similar to Leidenfrost effect reported for liquid droplet evaporating plate which temperature above boiling liquid. An analogy depicted phenomenon rapid solid contact hot Similarly droplet, we observe that, while melting, very mobile: translation rotation. A hole was drilled in allowed canalising melted Under these conditions, discover that rotation...

This study investigates theoretically and numerically the propulsive sliding of a slender body. The body sustains transverse propagative wave along its main axis, undergoes anisotropic friction caused by surface texture on floor. A model accounting for anisotropy frictional forces acting is implemented. describes force gives optimal undulating parameters efficient forward propulsion. characteristics are effectively compared to motion slithering snakes, as well with sandfish lizards swimming...

Eggs are key ingredients in our kitchens because of their nutritional values and functional properties such as foaming, emulsifying gelling, offering a wide variety culinary achievements. They also constitute ideal objects to illustrate myriad scientific concepts. In this article, we focus on several experiments (egg-speriments) that involve the singular liquids contained inside eggshell, especially egg white. We first characterize rheology an white rotational rheometer for constant...