#dropletimpact — Public Fediverse posts

From smooth liquid sheets to chaotic crowns, increasing impact speed transforms droplet splashing.

This work links that transition to Reynolds number and uncovers how instabilities shape droplet size and velocity.

🔗 https://doi.org/10.1063/5.0321372

#dropletimpact #FluidMechanics #splash #reynoldsnumber #physics

Day 1 recap at #LeidenForce Winter School:

🔹David Quéré (ESPCI): overview of Leidenfrost regimes and phenomena.

🔹Detlef Lohse @utwente : Leidenfrost impacts, jet formation, impact phases & key parameters.

#Leidenfrost #WinterSchool #FluidDynamics #DropletImpact #Physics

Charged Drops Don’t Splash

When a droplet falls on a surface, it spreads itself horizontally into a thin lamella. Sometimes — depending on factors like viscosity, impact speed, and air pressure — that drop splashes, breaking up along its edge into myriad smaller droplets. But a new study finds that a small electrical charge is enough to suppress a drop’s splash, as seen below.

The drop’s electrical charge builds up along the drop’s surface, providing an attraction that acts somewhat like surface tension. As a result, charged drops don’t lift off the surface as much and they spread less overall; both factors inhibit splashing.* The effect could increase our control of droplets in ink jet printing, allowing for higher resolution printing. (Image and research credit: F. Yu et al.; via APS News)

*Note that this only works for non-conductive surfaces. If the surface is electrically conductive, the charge simply dissipates, allowing the splash to occur as normal.

#dropletImpact #droplets #electricalField #electrohydrodynamics #fluidDynamics #lamella #physics #science #splashes #splashing

Hot Droplets Bounce

In the Leidenfrost effect, room-temperature droplets bounce and skitter off a surface much hotter than the drop’s boiling point. With those droplets, a layer of vapor cushions them and insulates them from the hot surface. In today’s study, researchers instead used hot or burning drops (above) and observed how they impact a room-temperature surface. While room-temperature droplets hit and stuck (below), hot and burning droplets bounced (above).

In this case, the cushioning air layer doesn’t come from vaporization. Instead, the bottom of the falling drop cools faster than the rest of it, increasing the local surface tension. That increase in surface tension creates a Marangoni flow that pulls fluid down along the edges of the drop. That flow drags nearby air with it, creating the cushioning layer that lets the drop bounce. In this case, the authors called the phenomenon “self-lubricating bouncing.” (Image and research credit: Y. Liu et al.; via Ars Technica)

#bouncingDroplets #dropletImpact #entrainment #fluidDynamics #marangoniEffect #physics #science

Hot Droplets Bounce

In the Leidenfrost effect, room-temperature droplets bounce and skitter off a surface much hotter than the drop’s boiling point. With those droplets, a layer of vapor cushions them and insulates them from the hot surface. In today’s study, researchers instead used hot or burning drops (above) and observed how they impact a room-temperature surface. While room-temperature droplets hit and stuck (below), hot and burning droplets bounced (above).

In this case, the cushioning air layer doesn’t come from vaporization. Instead, the bottom of the falling drop cools faster than the rest of it, increasing the local surface tension. That increase in surface tension creates a Marangoni flow that pulls fluid down along the edges of the drop. That flow drags nearby air with it, creating the cushioning layer that lets the drop bounce. In this case, the authors called the phenomenon “self-lubricating bouncing.” (Image and research credit: Y. Liu et al.; via Ars Technica)

#bouncingDroplets #dropletImpact #entrainment #fluidDynamics #marangoniEffect #physics #science

Hot Droplets Bounce

In the Leidenfrost effect, room-temperature droplets bounce and skitter off a surface much hotter than the drop’s boiling point. With those droplets, a layer of vapor cushions them and insulates them from the hot surface. In today’s study, researchers instead used hot or burning drops (above) and observed how they impact a room-temperature surface. While room-temperature droplets hit and stuck (below), hot and burning droplets bounced (above).

In this case, the cushioning air layer doesn’t come from vaporization. Instead, the bottom of the falling drop cools faster than the rest of it, increasing the local surface tension. That increase in surface tension creates a Marangoni flow that pulls fluid down along the edges of the drop. That flow drags nearby air with it, creating the cushioning layer that lets the drop bounce. In this case, the authors called the phenomenon “self-lubricating bouncing.” (Image and research credit: Y. Liu et al.; via Ars Technica)

#bouncingDroplets #dropletImpact #entrainment #fluidDynamics #marangoniEffect #physics #science

Hot Droplets Bounce

In the Leidenfrost effect, room-temperature droplets bounce and skitter off a surface much hotter than the drop’s boiling point. With those droplets, a layer of vapor cushions them and insulates them from the hot surface. In today’s study, researchers instead used hot or burning drops (above) and observed how they impact a room-temperature surface. While room-temperature droplets hit and stuck (below), hot and burning droplets bounced (above).

In this case, the cushioning air layer doesn’t come from vaporization. Instead, the bottom of the falling drop cools faster than the rest of it, increasing the local surface tension. That increase in surface tension creates a Marangoni flow that pulls fluid down along the edges of the drop. That flow drags nearby air with it, creating the cushioning layer that lets the drop bounce. In this case, the authors called the phenomenon “self-lubricating bouncing.” (Image and research credit: Y. Liu et al.; via Ars Technica)

#bouncingDroplets #dropletImpact #entrainment #fluidDynamics #marangoniEffect #physics #science

Hot Droplets Bounce

In the Leidenfrost effect, room-temperature droplets bounce and skitter off a surface much hotter than the drop’s boiling point. With those droplets, a layer of vapor cushions them and insulates them from the hot surface. In today’s study, researchers instead used hot or burning drops (above) and observed how they impact a room-temperature surface. While room-temperature droplets hit and stuck (below), hot and burning droplets bounced (above).

In this case, the cushioning air layer doesn’t come from vaporization. Instead, the bottom of the falling drop cools faster than the rest of it, increasing the local surface tension. That increase in surface tension creates a Marangoni flow that pulls fluid down along the edges of the drop. That flow drags nearby air with it, creating the cushioning layer that lets the drop bounce. In this case, the authors called the phenomenon “self-lubricating bouncing.” (Image and research credit: Y. Liu et al.; via Ars Technica)

#bouncingDroplets #dropletImpact #entrainment #fluidDynamics #marangoniEffect #physics #science

Drops on the Edge

Drops impacting a dry hydrophilic surface flatten into a film. Drops that impact a wet film throw up a crown-shaped splash. But what happens when a drop hits the edge of a wet surface? That’s the situation explored in this video, where blue-dyed drops interact with a red-dyed film. From every angle, the impact is complex — sending up partial crown splashes, generating capillary waves that shift the contact line, and chaotically mixing the drop and film’s liquids. (Video and image credit: A. Sauret et al.)

#2024gofm #crownSplash #dropletImpact #droplets #flowVisualization #fluidDynamics #fluidsAsArt #physics #science #wetting

Drops on the Edge

Drops impacting a dry hydrophilic surface flatten into a film. Drops that impact a wet film throw up a crown-shaped splash. But what happens when a drop hits the edge of a wet surface? That’s the situation explored in this video, where blue-dyed drops interact with a red-dyed film. From every angle, the impact is complex — sending up partial crown splashes, generating capillary waves that shift the contact line, and chaotically mixing the drop and film’s liquids. (Video and image credit: A. Sauret et al.)

#2024gofm #crownSplash #dropletImpact #droplets #flowVisualization #fluidDynamics #fluidsAsArt #physics #science #wetting

Drops on the Edge

Drops impacting a dry hydrophilic surface flatten into a film. Drops that impact a wet film throw up a crown-shaped splash. But what happens when a drop hits the edge of a wet surface? That’s the situation explored in this video, where blue-dyed drops interact with a red-dyed film. From every angle, the impact is complex — sending up partial crown splashes, generating capillary waves that shift the contact line, and chaotically mixing the drop and film’s liquids. (Video and image credit: A. Sauret et al.)

#2024gofm #crownSplash #dropletImpact #droplets #flowVisualization #fluidDynamics #fluidsAsArt #physics #science #wetting

Drops on the Edge

Drops impacting a dry hydrophilic surface flatten into a film. Drops that impact a wet film throw up a crown-shaped splash. But what happens when a drop hits the edge of a wet surface? That’s the situation explored in this video, where blue-dyed drops interact with a red-dyed film. From every angle, the impact is complex — sending up partial crown splashes, generating capillary waves that shift the contact line, and chaotically mixing the drop and film’s liquids. (Video and image credit: A. Sauret et al.)

#2024gofm #crownSplash #dropletImpact #droplets #flowVisualization #fluidDynamics #fluidsAsArt #physics #science #wetting