# gst: a body of revolution with a cat’s toy mechanism.

AA << introduce a class of examples which provide an affine generalization of the nonholonomic problem of a convex body rolling without slipping on the plane. >>

️

They << prove that (this system can be) integrable if the generalized momentum M is vertical (i.e. parallel to γ) and exhibit numerical evidence that it is chaotic otherwise. >>️

M. Costa Villegas, L.C. García-Naranjo. Affine generalizations of the nonholonomic problem of a convex body rolling without slipping on the plane. arXiv: 2409.08072v1 [math-ph]. Sep 12, 2024. 

https://arxiv.org/abs/2409.08072

Also: transition, chaos, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, transition, chaos

# gst: multi-component droplets may exhibit self-lubricating effects

<< Over the past decade, there has been a growing interest in the study of multicomponent drops. These drops exhibit unique phenomena, as the interplay between hydrodynamics and the evolving physicochemical properties of the mixture gives rise to distinct and often unregulated behaviors. >>

<< Of particular interest is the complex dynamic behavior of the drop contact line, which can display self-lubrication effect. The presence of a slipping contact line in self-lubricating multicomponent drops can suppress the coffee-stain effect, conferring valuable technological applications. >>

Huanshu Tan, Detlef Lohse, Xuehua Zhang. Self-Lubricating Drops. arXiv: 2403.01207v1 [physics.flu-dyn]. Mar 2, 2024

https://arxiv.org/abs/2403.01207

Also: drop droplet droploid, in https://www.inkgmr.net/kwrds.html

Keywords: drop, droplet, droploid, multicomponent drops, drop contact line, self-lubrication

# gst: apropos of bouncing, even balls that undergo rolling are typically found to lift off slipping.

<< A detailed set of experiments are described that capture over a 1000 different instances of the bounce of a golf ball. (..) Data are presented from two different turfs; one artificial and one from a typical tee. >>

<< A better fit to the data is found using a non-physical piecewise-affine landing to lift-off relationship, which distinguishes between cases that bounce in pure slip from those that undergo rolling. Nevertheless, even balls that undergo rolling are typically found to lift off slipping, having undergone spin reversal. >>

Stanisław W. Biber, Kristian M. Jones, et al. Measurements and linearized models for golf ball bounce. arXiv: 2302.02758v1 [physics.class-ph]. Jan 13, 2023. 

https://arxiv.org/abs/2302.02758

Also

keyword 'bouncing' | 'rolling' | 'slipping' in FonT

https://flashontrack.blogspot.com/search?q=bouncing

https://flashontrack.blogspot.com/search?q=rolling

https://flashontrack.blogspot.com/search?q=slipping

Keywords: gst, bouncing, rolling,  slipping

# gst: apropos of transitions, the transition from sticking to slipping.

<< From hydrogels and plastics to liquid crystals, soft solids cover a wide array of synthetic and biological materials that play key enabling roles in advanced technologies >>️

<< Attempts to study the interactions between soft solids and liquids have largely focused on the wetting of soft solids and its resulting deformation at equilibrium or in a quasi-static state. Here, (AA) consider the frequently encountered case of unsteady wetting of a liquid on a soft solid and show that transient deformation of the solid is necessary to understand unsteady wetting behaviours. >>️

AA << find that the initial spreading of the liquid occurs uninterrupted in the absence of solid deformation. This is followed by intermittent spreading, in which transient deformation of the solid at the three-phase contact line (CL) causes the CL motion to alternate alternation between CL sticking and slipping. (They) identify the spreading rate of liquids and the viscoelastic reacting rate of soft solids as the two competing factors in dictating intermittent spreading. (They)  formulate and validate experimentally the conditions required for the contact line to transition from sticking to slipping. By considering the growing deformation of soft solids as dynamic surface heterogeneities, (AA) proposed conditions for stick-slip transition in unsteady wetting on soft solids broaden the classical theory on wetting hysteresis on rigid solids. >>️

Surjyasish Mitra, Quoc Vo, Marcus Lin, Tuan Tran. Unsteady wetting of soft solids. arXiv:2211.07043v1 [cond-mat.soft]. Nov 13, 2022.

https://arxiv.org/abs/2211.07043

Also

keyword 'drop' | 'droplet' | 'droploids' in FonT

https://flashontrack.blogspot.com/search?q=drop

https://flashontrack.blogspot.com/search?q=droplet

https://flashontrack.blogspot.com/search?q=droploids

keyword 'goccia' in Notes 

(quasi-stochastic poetry) 

https://inkpi.blogspot.com/search?q=goccia

Keywords: gst, behav, behaviour, transition, soft solids, drop, droplet, sticking, slipping.

# gst: apropos of slipping, the motion on a deformable ground under fast-moving sheets

<< Backed by experimental data from a laboratory machine that simulates the huge forces involved in glacier flow, glaciologists have written an equation that accounts for the motion of ice that rests on the soft, deformable ground underneath unusually fast-moving parts of ice sheets. >>

<< That equation - or "slip law" - is a tool that scientists can include in computer models of glacier movement over the deformable beds of mud, sand, pebbles, rocks and boulders under glaciers such as the West Antarctic Ice Sheet, >> Neal Iverson

<< Models using the new slip law could better predict how quickly glaciers are sliding, how much ice they're sending to oceans and how that would affect sea-level rise. >>

Neal Iverson. Experiments lead to slip law for better forecasts of glacier speed, sea-level rise. Iowa State University. Apr 2, 2020.

https://m.phys.org/news/2020-04-law-glacier-sea-level.html

<< These observations should help to solve the long-standing problem of constructing a generalized slip law that combines the processes of hard-bedded sliding and bed deformation. >>

Lucas K. Zoet, Neal R. Iverson. A slip law for glaciers on deformable beds.  Science. Vol. 368, Issue 6486, pp. 76-78 doi: 10.1126/science.aaz1183.  Apr 3, 2020.

https://science.sciencemag.org/content/368/6486/76

# s-phys: if you take a large collection of chaotic balls ...

<< If  you  take  a  large  collection  of  balls  in  contact  and  force  some  of  them  to  spin,  they  can  behave  like a  set  of  gears,  with  each  ball  rotating  without  slipping.  Experiments  and  theory  show  that  this synchronized  motion  can  be predicted  even  when the initial  motion  involves  seemingly  random slipping  between  the  spheres  (like  the  skipping  of  gears).  The  researchers  say  that  the  ability  to predict  this  collective  motion  could  lead  to  three-dimensional  gear  systems  in  which  manipulations of  one or two spheres allows complete control  of  the  rotational  motion  of  the  others >>

Michael  Schirber. Focus:  Balls  as  3D  Gears. June 24,  2016.

https://physics.aps.org/articles/v9/71

D. V. Stager, N. A. M. Araujo, and H. J. Herrmann. Prediction and Control of Slip-Free Rotation States in Sphere Assemblies. Phys. Rev. Lett. 116, 254301. Publ. 24 June 2016

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.254301