Spontaneous concentrations of solids through two-way drag forces between gas and sedimenting particles

Lambrechts, Michiel; Johansen, Anders; Capelo, Holly L.; Blum, Jürgen; Bodenschatz, Eberhard

doi:10.1051/0004-6361/201526272

Cited by 23 publications

(40 citation statements)

References 56 publications

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“…(ii) Turbulence. It is well known that clumping instabilities driven by particle inertia or wave-particle resonance operate in dust-gas interactions (e.g., Lambrechts et al 2016;Squire & Hopkins 2018), and may also operate in cloudlet-gas interactions.…”

Section: Discussionmentioning

confidence: 99%

Is multiphase gas cloudy or misty?

Grönke

2020

Monthly Notices of the Royal Astronomical Society: Letters

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Cold T ∼ 10 4 K gas morphology could span a spectrum ranging from large discrete clouds to a fine 'mist' in a hot medium. This has myriad implications, including dynamics and survival, radiative transfer, and resolution requirements for cosmological simulations. Here, we use 3D hydrodynamic simulations to study the pressure-driven fragmentation of cooling gas. This is a complex, multi-stage process, with an initial Rayleigh-Taylor unstable contraction phase which seeds perturbations, followed by a rapid, violent expansion leading to the dispersion of small cold gas 'droplets' in the vicinity of the gas cloud. Finally, due to turbulent motions, and cooling, these droplets may coagulate. Our results show that a gas cloud 'shatters' if it is sufficiently perturbed out of pressure balance (δP/P ∼ 1), and has a large final overdensity χ f 300, with only a weak dependence on the cloud size. Otherwise, the droplets reassemble back into larger pieces. We discuss our results in the context of thermal instability, and clouds embedded in a shock heated environment.

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Section: Discussionmentioning

confidence: 99%

Is multiphase gas cloudy or misty?

Grönke

2020

Monthly Notices of the Royal Astronomical Society: Letters

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“…Here, certain conditions in protoplanetary discs (solid to gas ratio) might reduce the necessary particle size for concentration to occur (Yang et al 2017). First specific laboratory experiments accompanying simulations were initiated to verify these ideas in a sedimenting cloud of grains (Lambrechts et al 2016). More recently, clouds of grains in a dilute gas levitated in a rotating setup for the first time actually showed a transition to sensitive collective behaviour (Schneider et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Are Pebble Pile Planetesimals Doomed?

Demirci

Kruss

Teiser

et al. 2019

Monthly Notices of the Royal Astronomical Society

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In parabolic flight experiments we studied the wind induced erosion of granular beds composed of spherical glass beads at low gravity and low ambient pressure. Varying g-levels were set by centrifugal forces. Expanding existing parameter sets to a pressure range between p = 300 − 1200 Pa and to g-levels of g = 1.1 − 2.2 m s −2 erosion thresholds are still consistent with the existing model for wind erosion on planetary surfaces by Shao & Lu (2000). These parameters were the lowest values that could technically be reached by the experiment. The experiments decrease the necessary range of extrapolation of erosion thresholds from verified to currently still unknown values at the conditions of planetesimals in protoplanetary discs. We apply our results to the stability of planetesimals. In inner regions of protoplanetary discs, pebble pile planetesimals below a certain size are not stable but will be disassembled by a head wind.

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“…More recently, new dusty instabilities have appeared in numerical simulations (Lorén-Aguilar & Bate 2015Lambrechts et al 2016) and analytical calculations ), but their physical underpinnings are not yet well understood.…”

Section: Introductionmentioning

confidence: 99%

A Thermodynamic View of Dusty Protoplanetary Disks

Lin

Youdin

2017

ApJ

123

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Small solids embedded in gaseous protoplanetary disks are subject to strong dust-gas friction. Consequently, tightly coupled dust particles almost follow the gas flow. This near conservation of the dust-to-gas ratio along streamlines is analogous to the near conservation of entropy along flows of (dust-free) gas with weak heating and cooling. We develop this thermodynamic analogy into a framework to study dusty gas dynamics in protoplanetary disks. We show that an isothermal dusty gas behaves like an adiabatic pure gas, and that finite dust-gas coupling may be regarded as effective heating/cooling. We exploit this correspondence to deduce that (1) perfectly coupled, thin dust layers cannot cause axisymmetric instabilities; (2) radial dust edges are unstable if the dust is vertically well-mixed; (3) the streaming instability necessarily involves a gas pressure response that lags behind dust density; and (4) dust-loading introduces buoyancy forces that generally stabilize the vertical shear instability associated with global radial temperature gradients. We also discuss dusty analogs of other hydrodynamic processes (e.g., Rossby wave instability, convective overstability, and zombie vortices) and how to simulate dusty protoplanetary disks with minor tweaks to existing codes for pure gas dynamics.

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Spontaneous concentrations of solids through two-way drag forces between gas and sedimenting particles

Cited by 23 publications

References 56 publications

Is multiphase gas cloudy or misty?

Is multiphase gas cloudy or misty?

Are Pebble Pile Planetesimals Doomed?

A Thermodynamic View of Dusty Protoplanetary Disks

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