# gst: apropos of attractive-- repulsive potentials in free boundary movements, stochastic and deterministic dynamics of free boundaries atop turbulent convection

AA << present a low-dimensional model that explains the coupled dynamics of floating boundaries that interact with turbulent flows in thermal convection. >>

<< The model consists of Langevin-type, stochastic differential equations, which captures the deterministic and stochastic movements of boundaries shown in an earlier experiment J.-Q. Zhong et al. [Phys. Rev. E 75, 055301(R) (2007)]. From the displacement, speed, and acceleration of the boundaries, (They) construct the force potentials that underlie two distinct boundary-size-dependent behaviors. >>

<< Namely, (AA) find a repulsive potential (when the boundary is small) that leads to an oscillatory state and an attractive potential (when the boundary is large) that leads to a trapped state. >>

<< The boundary movements, which are subject to thermal convection underneath, also inform us of the mean speed and turbulent fluctuations of the flows. >>

Wen-Tao Wu, Jun Zhang, Jin-Qiang Zhong. Stochastic and deterministic dynamics of free boundaries atop turbulent convection. Phys. Rev. Fluids 10, 053504. May 9, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.10.053504

Also: disorder & fluctuations, turbulence, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, convection, floating 

boundaries, turbulence, turbulent flows, turbulent fluctuations, disorder & fluctuations, trapped states

# gst: apropos of unexpected thresholds, the minimum temperature for levitating a droplet

<< During the Leidenfrost effect, a thin insulating vapor layer separates an evaporating liquid from a hot solid. (AA) demonstrate that Leidenfrost vapor layers can be sustained at much lower temperatures than those required for formation. >>

<< the explosive failure point is nearly independent of material and fluid properties, suggesting a purely hydrodynamic mechanism determines this threshold. >>️

Dana Harvey, Joshua Mendez Harper, Justin C. Burton. Minimum Leidenfrost Temperature on Smooth Surfaces. Phys. Rev. Lett. 127, 104501. Sep 1, 2021.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.104501

Christopher Crockett. The Minimum Temperature for Levitating Droplets. Physics 14, s107. Sep 1, 2021.

https://physics.aps.org/articles/v14/s107

Also

keyword 'drop' | 'droplet' in FonT

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

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

keywords: gst, drop, droplet, waves, buckling, lubrication, convection, interfacial flows, threshold, levitation, bubble.

# gst: global dust storms from waves in thin air.

<< Mars has a very thin atmosphere, with nearly one hundredth the density of ours on Earth, and gravity pulls with little more than one third of the strength we feel on our planet. As a result, dust storms can go global. >>

Waves in thin air with broad effects. Instituto de Astrofísica e Ciencias do Espaco. Mar 17, 2020.

https://m.phys.org/news/2020-03-thin-air-broad-effects.html

G.Gilli,  F.Forget, et al. Impact of Gravity Waves on the Middle Atmosphere of Mars: A Non‐Orographic Gravity Wave Parameterization Based on Global Climate Modeling and MCS Observations. Journal of Geophysical Research: Planets. Volume 125, Issue 3.  doi: 10.1029/2018JE005873. Feb 7, 2020.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JE005873