Categorization of Brazil nut effect and its reverse under less-convective conditions for microgravity geology

Chujo, Toshihiro; Mori, Osamu; Kawaguchi, Jun’ichiro; Yano, Hajime

doi:10.1093/mnras/stx3092

Cited by 17 publications

(14 citation statements)

References 35 publications

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“…2017; Chujo et al. 2018) show that mechanisms leading to inverse grading remain active on small bodies, but their efficacy in retaining this structure in flowing conditions is not yet known. In this context, we mention the recent separation-flux model of Pudasaini & Fischer (2020).…”

Section: Binary Mixturesmentioning

confidence: 99%

“…The appropriateness of this assumption on small bodies, where gravity is much smaller, is still an unsettled question. Recent works (Maurel et al 2017;Chujo et al 2018) show that mechanisms leading to inverse grading remain active on small bodies, but their efficacy in retaining this structure in flowing conditions is not yet known. In this context, we mention the recent separation-flux model of Pudasaini & Fischer (2020).…”

Section: Binary Mixturesmentioning

confidence: 99%

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Granular flow on a rotating and gravitating elliptical body

et al. 2021

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Section: Binary Mixturesmentioning

confidence: 99%

Section: Binary Mixturesmentioning

confidence: 99%

Granular flow on a rotating and gravitating elliptical body

et al. 2021

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“…The migration of regolith materials on asteroids is possible to be initiated by some disturbance factors, including but not limited to global change of the surface dynamical environment due to varying spin state [15], and exogenous excitation, such as impact events which could give rise to stress waves and seismic shaking [16,17]. A slow mechanism that can modify the spin rates and obliquities of small bodies by thermal radiation forces and torques, referred to as Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect [18], plays an important role in driving the surface evolution process of small bodies.…”

Section: Introductionmentioning

confidence: 99%

Long-term Trends of Regolith Movement on the Surface of Small Bodies

Huang

Cheng

et al. 2022

Preprint

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This paper studies the long-term migration of disturbed regolith materials on the surface of Solar System small bodies from the viewpoint of nonlinear dynamics. We propose an approximation model for secular mass movement, which combines the complex topography and irregular gravitational field. Choosing asteroid 101955 Bennu as a representative, the global change of the dynamical environment is examined, which presents a division of the creeping-sliding-shedding regions for a spun-up asteroid. In the creeping region, the dynamical equation of disturbed regolith grains is established based on the assumption of "trigger-slide" motion mode. The equilibrium points, local manifolds and large-scale trajectories of the system are calculated to clarify the dynamical characteristics of long-term regolith movement. Generally, we find that for a low spin rate, the surface regolith grains flow toward the middle latitudes from the polar/equatorial regions, which is dominated by the gradient of the geopotential. While spun up to a high rate, regolith grains tend to migrate toward the equator, which happens in parallel with a topological shift of the local equilibria at low latitudes. From a long-term perspective, we find the equilibrium points dominate the global trends of regolith movements. Using the methodology developed in this paper, we give a prospect or retrospect to the secular motion of regolith materials during the spin-up process, and the results reveal a significant regulatory role of the equilibria. Through a detailed look at the dynamical scheme under different spin rates, we achieve a macro forecast of the global trends of regolith motion during the spin-up process, which explains the global geologic evolution driven by the long-term movements of regolith materials.

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“…The rapidly attenuated seismic pulse or 'jolt' model (Nolan et al, 1992;Greenberg et al, 1994Greenberg et al, , 1996Nolan et al, 2001;Thomas and Robinson, 2005) is consistent with strong attenuation in dry laboratory granular materials at kHz frequencies (Hostler and Brennen, 2005;O'Donovan et al, 2016), but qualitatively differs from the slowly attenuating seismic reverberation model (Cintala et al, 1978;Cheng et al, 2002;Richardson et al, 2004Richardson et al, , 2005, that is supported by measurements of slow seismic attenuation rates in lunar regolith (Dainty et al, 1974;Toksöz et al, 1974;Nakamura, 1976). While both impact-induced seismic jolt and reverberation can cause crater erasure and crater rim degradation (Veverka et al, 2001;Nolan et al, 2001;Richardson et al, 2004Richardson et al, , 2005Thomas and Robinson, 2005;Asphaug, 2008), size segregation induced by the Brazil-nut effect could depend on sustained vibrations or reverberation (e.g., Miyamoto et al 2007;Tancredi et al 2012;Matsumura et al 2014;Tancredi et al 2015;Perera et al 2016;Maurel et al 2017;Chujo et al 2018), though a single seismic pressure pulse can also leave boulders on the surface (Wright et al, 2020) via ballistic sorting (Shinbrot et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Propagation and attenuation of pulses driven by low velocity normal impacts in granular media

Quillen,

Neiderbach,

Suo

et al. 2022

Preprint

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We carry out experiments of low velocity normal impacts into granular materials that fill an approximately cylindrical 11 gallon tub. Motions in the granular medium are tracked with an array of 7 embedded accelerometers. Longitudinal pulses excited by the impact broaden and attenuate as a function of travel distance from the site of impact. Pulse propagation is not spherically symmetric about the site of impact. Peak amplitudes are about twice as large for the pulse propagating downward than at 45 degrees from vertical. An advection-diffusion model is used to estimate the dependence of pulse properties as a function of travel distance from the site of impact. The power law forms for pulse peak pressure, velocity and seismic energy depend on distance from impact to a power of -2.5 and this rapid decay is approximately consistent with our experimental measurements. Our experiments support a seismic jolt model, giving rapid attenuation of impact generated seismic energy into rubble asteroids, rather than a reverberation model, where seismic energy slowly decays. We apply our diffusive model to estimate physical properties of the seismic pulse that will be excited by the forthcoming DART mission impact onto the secondary, Dimorphos, of the asteroid binary (65803) Didymos system. We estimate that the pulse peak acceleration will exceed the surface gravity as it travels through the asteroid.

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Categorization of Brazil nut effect and its reverse under less-convective conditions for microgravity geology

Cited by 17 publications

References 35 publications

Granular flow on a rotating and gravitating elliptical body

Granular flow on a rotating and gravitating elliptical body

Long-term Trends of Regolith Movement on the Surface of Small Bodies

Propagation and attenuation of pulses driven by low velocity normal impacts in granular media

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