Rolling Down Soft Surfaces

Place a rigid ball on a hard vertical surface, and it will free fall. Stick a liquid drop there, and it will slide down. But researchers discovered that with a soft sphere and a soft surface, it’s possible to roll down a vertical wall. The effect requires just the right level of squishiness for both the wall and sphere, but when conditions are right, the 1-millimeter radius sphere rolls (with a little slipping) down the wall.

Rolling requires torque, something that’s usually lacking on a vertical surface. But the team found that their soft spheres got the torque needed to roll from their asymmetric contact with the surface. More of the sphere contacted above its centerline than below it. The researchers compared the way the sphere contacted the surface to a crack opening (at the back of the sphere) and a crack closing (at the front of the sphere). That asymmetry creates just enough torque to roll the sphere slowly. The team hopes their discovery opens up new possibilities for soft robots to climb and descend vertical surfaces. (Image and research credit: S. Mitra et al.; via Gizmodo)

#adhesion #fluidDynamics #physics #science #slip #softMatter #solidMechanics

Chaotic Hose Instability

Steve Mould is back with another video looking at wild fluid behaviors. This time he’s considering hose instabilities like the one that makes a water-carrying hose beyond a certain length to whip wildly back and forth. He tries to track down the reasoning for these flexible hoses snapping and whipping. In truth, both the hoses and the wind dancers do their thing due to interactions between the elasticity of the hose and the fluid dynamics of the flows within. These applications are ripe for a few control volume thought experiments. (Video and image credit: S. Mould)

#chaos #elasticity #fluidDynamics #physics #science #solidMechanics

Ultra-Soft Solids Flow By Turning Inside Out

Can a solid flow? What would that even look like? Researchers explored these questions with an ultra-soft gel (think 100,000 times softer than a gummy bear) pumped through a ring-shaped annular pipe. Despite its elasticity — that tendency to return to an original shape that distinguishes solids from fluids — the gel does flow. But after a short distance, furrows form and grow along the gel’s leading edge.

Since the gel alongside the pipe’s walls can’t slide due to friction, the gel flows by essentially turning itself inside out. Inner portions of the gel flow forward and then split off toward one of the walls as they reach the leading edge. This eversion builds up lots of internal stress in the gel, and furrowing — much like crumpling a sheet of paper — relieves that stress. (Image and research credit: J. Hwang et al.; via APS News)

#flowVisualization #fluidDynamics #instability #physics #pipeFlow #science #softMatter #solidMechanics #stress

Congratulations to Sébastien Court, Associate Professor at the Department of #Mathematics and the DiSC of @uniinnsbruck, for receiving the prestigious Research Award of the Stiftung Südtiroler Sparkasse for his recent, outstanding research papers with contributions to the theory of partial differential equations, particularly in the field of solid and fluid mechanics: https://www.uibk.ac.at/en/disc/news/research-award-court/

#SolidMechanics #FluidMechanics

There will also be 4 special sessions,

https://spheric2025.upc.edu/index.php/call-for-special-sessions/

for #Aerospace and maritime applications, #SolidMechanics, #CoastalEngineering (an #SPH classic), and one focused on #RenewableEnergy modelling and innovations through #SPH

#SPH_ #SmoothedParticleHydrodynamics

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#SPHERIC2025 will be in #Barcelona
https://spheric2025.upc.edu/

It will be the first #SPHERIC #conference to break from the "classic" SPHERIC International Workshop format that was also employed for the SPHERIC 2022 I organized in Catania, and closer to other more traditional conferences (hence also the change in name, to SPHERIC World Conference).

1/

#SPH #CFD #SolidMechanics #AstroPhysics #ParticleMethods

These days glass screens travel with us everywhere, and they can take some big hits on the way. Manufacturers have made tougher glass, but they continue to look for ways to protect our screens. Recently, a study suggested that non-Newtonian fluids are well-suited to the task.

The team explored the physics of sandwiching a layer of fluid between a glass top layer and an LCD screen bottom layer, mimicking structures found in electronic devices. Through simulation, they searched for the fluid characteristics that would best minimize the forces felt by the solid layers during an impact. They found that shear-thinning fluids — fluids that, like paint or shampoo, get runnier when they’re deformed — provided the best protection. Having the impact energy go into reducing the local viscosity of the fluid stretches the length of time the impact affects the glass, which lowers the bending forces on it and helps avoid breakage. (Image credit: G. Rosenke; research credit: J. Richards et al.; via Physics World)

https://fyfluiddynamics.com/2024/05/saving-screens-with-shear-thinning-fluids/

#engineering #fluidDynamics #nonNewtonianFluids #numericalSimulation #physics #science #shearThinning #solidMechanics #viscosity

Soft materials tend to be sticky, and once they’re adhered to a surface, they’re often harder to remove than they were to attach — think of Scotch tape stuck to a desk. This difficulty separating sticky things — known as adhesion hysteresis — has been attributed to various causes, like energy lost to viscoelasticity or age-related chemical bonding. But a new study shows that both those explanations are unnecessary.

Instead, the difficult removal comes from the way two surfaces separate in fits and starts. No two surfaces are perfectly smooth, and soft surfaces are able to conform to all the nooks and crannies of their partner surface. That molding results in a lot of surface contact, all of which must break for the materials to detach. That peeling doesn’t take place smoothly. Instead, the two surfaces part a little at a time in discrete jumps, as shown in the image above. The colors in the illustration show how much energy is dissipated in each jump, with darker colors indicating higher energy. The team found that this stick-slip mechanism is enough to account for the struggles we have un-sticking objects. They’re now looking at how water affects these narrow meeting places between sticky surfaces. (Image and research credit: A. Sanner et al.; via Physics World)

https://fyfluiddynamics.com/2024/05/unsticking-in-jumps/

#adhesion #fluidDynamics #physics #science #solidMechanics #stickSlip #surfaceRoughness

To fly stably, parachutes need to deform and allow some air to pass through their canopy. In this video, researchers investigate kirigimi parachutes, inspired by a form of paper art that uses cuts to create three-dimensional shapes. After laser-cutting, these disks are dropped — or placed in a wind tunnel — to observe how they “fly” at different speeds. Sometimes they flutter or bend; other shapes elongate in the flow. (Video and image credit: D. Lamoureux et al.; via GoSM)

https://fyfluiddynamics.com/2024/05/kirigami-parachutes/

#2024gosm #drag #fluidDynamics #parachutes #physics #science #solidMechanics

Congratulations Dr. Sharan! 🥳 So very proud of you & your journey. #phddone #Stochastic #computationalsciences #materialmodelling #solidmechanics #appliedmathematics @tuBraunschweig
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RT @S_K_Shivanand
I am pleased to inform you that my PhD dissertation is now available online at https://leopard.tu-braunschweig.de/receive/dbbs_mods_00071795.
https://twitter.com/S_K_Shivanand/status/1604781454617202688

#introduction 🤓

I am a physicist specialized in #fluiddynamics and #solidmechanics with experience in #interdisciplinary research and #neuroscience. I develop modelling tools to predict #fluidstructure interactions in the #brain.

My research focuses on the role of intracranial vessel pulsation in #neurodegenerative diseases. I am highlighting how measurements of intracranial fluid dynamics combined with #biomechanics modelling can help to better understand and characterize brain #ageing.

doodling on my #whiteboard 😋

and tried to remember some formulas from my mechanical-engineering study xD

drawing on whiteboards is still so much fun, I really want to improve this.

#art #mastoart #solidmechanics

In #SolidMechanics, #stress has some counter-intuitive properties, particularly when you rotate the coordinate system. The values of normal and shear stress transform according to the rules of #second-order #tensors, which is a step above #vectors (first-order tensors).

#Mechanics #Mathematics #Engineering

This little graphical demonstration shows one example of such a state. The #AnimatedGif was produced a routine written in #WxMaxima. 2/2

#Mathematics #TheoryOfElasticity #Mechanics #SolidMechanics #Engineering #MyWork #CCBYSA #WorkInProgress #FreeSoftware