On the influence of gravity on particle accumulation structures in high aspect-ratio liquid bridges

Capobianchi, Paolo; Lappa, Marcello

doi:10.1017/jfm.2020.882

Cited by 17 publications

(12 citation statements)

References 64 publications

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“…( 2)-(3), respectively. The Maxey-Riley equation has been integrated at the same time with these equations (the interested reader being referred to [22,23] for additional information about the solution of this equation and particle-wall interaction model).…”

Section: Grid Refinement and Numerical Methodsmentioning

confidence: 99%

An Investigation into the Behavior of Non-Isodense Particles in Chaotic Thermovibrational Flow

Crewdson¹,

Lappa²

2022

Fluid Dynamics &Amp; Materials Processing

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The ability to control the distribution of particles in a fluid is generally regarded as a factor of great importance in a variety of fields (manufacturing processes, biomedical applications, materials engineering and various particle separation processes, to cite a few). The present study considers the hitherto not yet addressed situation in which solid spherical particles are dispersed in a non-isothermal fluid undergoing turbulent vibrationally-induced convection (chaotic thermovibrational flow in a square cavity due to vibrations perpendicular to the imposed temperature difference). Although the possibility to use laminar thermovibrational flows (in microgravity) and turbulent flows of various types (in normal gravity conditions) to induce the accumulation of solid mass dispersed in a non-isodense fluid is already known, the interplay of finite-size finite-mass particles with chaotic flow in weightlessness conditions has never been considered. In the present study this subject is tackled through direct numerical solution of the fluid and particle tracking equations in the framework of a one-way coupling approach. Results are presented for relatively wide ranges of vibrational amplitude, particle size and density.

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Section: Grid Refinement and Numerical Methodsmentioning

confidence: 99%

An Investigation into the Behavior of Non-Isodense Particles in Chaotic Thermovibrational Flow

Crewdson¹,

Lappa²

2022

Fluid Dynamics &Amp; Materials Processing

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“…Equation (32) should therefore be considered as a condition limiting the range of allowed volume fraction from above. In the present work, some simulations have also been conducted in the limiting condition in which ϕ ∼ = O(10 −2 ) as some authors have found the inequality (originally derived in the literature for turbulent flows) to be overly conservative in situations for which the flow is laminar [37].…”

Section: Nondimensional Formulationmentioning

confidence: 99%

“…v = 0, ∂u/∂y = −Ma∂T/∂x, and ∂T/∂y = 0 at y = 1 (free surface) (37) where Ma is the Marangoni number defined as Ma = σ T ∆Td/µα (where σ T is the surface tension derivative with respect to temperature). Solid particles are seeded in the domain when the hydrothermal wave has reached its asymptotic state in terms of amplitude and frequency (particles being distributed uniformly and with velocity and temperature initially equal to those of the fluid).…”

Section: Initial and Boundary Conditionsmentioning

confidence: 99%

“…Although the exploration of the sensitivity of these phenomena to intrinsic and environmental factors may appear as exhausted given the number of valuable efforts described above, most recently a completely new line of inquiry has been originated by the discovery that these waves can support the formation of ordered structures produced by particles (tracers initially dispersed in liquid bridges for visualization purposes). Such findings (Schwabe et al [22]) have stimulated a number of research works focusing on aspects relating to the patterning behavior in these systems for conditions in which the presence of the dispersed phase is expected not to influence the properties of the carrier flow (dilute dispersions, see, e.g., Schwabe et al [23], Schwabe and Mizev [24], Pushkin et al [25], Melnikov et al [26], Lappa [27][28][29][30], Kuhlmann et al [31], Gotoda et al [32,33], Lappa [34], Melnikov and Shevtsova [35], Capobianchi and Lappa [36][37][38], Sakata et al [39]).…”

Section: Introductionmentioning

confidence: 99%

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On the Propagation of Hydrothermal Waves in a Fluid Layer with Two-Way Coupled Dispersed Solid Particles

Lappa

2022

Fluids

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The propagation of hydrothermal waves in a differentially heated shallow open cavity filled with a complex fluid (a mixture of an oil with solid spherical metallic particles) is investigated in the framework of a hybrid numerical two-way coupled Eulerian–Lagrangian methodology. We explore the response of this system to the solid mass fraction (mass load) and the particle size (Stokes number). The results show that particles and related (inertial and drag) effects can cause appreciable modifications in the properties of the wave, leading to a shrinkage of its velocity of propagation. Interesting dynamics can also be seen in terms of particle patterning behavior as the Stokes number is increased. Due to the joint action that distinct traveling rolls exert on the dispersed solid mass, related accumulation loops induced by centrifugal effects are progressively distorted and finally broken. Particles simply tend to cluster (as time increases) along the lower periphery of the main Marangoni circulation and, as a result of this mechanism and the different velocities of the return flow and the hydrothermal disturbance, a wavy boundary is formed, which separates the upper particle-rich area from a relatively depleted region next to the bottom wall.

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“…Accordingly, each droplet is tracked individually throughout the computational domain. Although this approach may look less convenient than other methods where all coexisting phases are dealt with in the framework of a single Eulerian treatment (typically based on the introduction of a volume of fraction variable or similar concepts, see, e.g., Capobianchi et al 48 and Lappa 49 ), the hybrid Eulerian–Lagrangian has distinct advantages, which make it particularly suitable (see, e.g., Capobianchi and Lappa; 50 Lappa and Burel; 51 and Lappa 52 ) for the analysis of the problems like that being addressed in the present work. For each droplet, in particular, a set of 3 differential equations are solved, which describe the evolution of its position (and velocity), mass, and temperature, respectively.…”

Section: Mathematical Modelmentioning

confidence: 99%

Three-dimensional simulation of clouds of multi-disperse evaporating saliva droplets in a train cabin

et al. 2021

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In line with recent ongoing efforts to collect crucial information about the mechanisms of virus diffusion and put them in relation to the effective complexity of the several natural or artificial environments where human beings leave and operate, the present study deals with the dispersion of evaporating saliva droplets in the cabin of an interregional train. A relevant physical model is constructed taking into account the state of the art in terms of existing paradigms and their ability to represent some fundamental aspects related to the evolution in time of a cloud of multi-disperse droplets. Conveniently, such a theoretical framework is turned into a computational one that relies on low Mach-number asymptotics and can therefore take advantage of the typical benefits (relatively low computational cost) associated with pressure-based methods. Numerical simulations are used to predict the flow established in the cabin as a result of the ventilation systems and related settings dictated by considerations on passenger comfort. The solution of two-way coupled Lagrangian evolution equations is used to capture the associated dynamics of the dispersed phase and predict its transport in conjunction with the peculiar topology of the considered flow and morphology of solid surfaces, which bound it (including the human beings). Typical physiological processes such as talking or coughing are considered. An analysis on the impact of the multiplicity of droplet sources is also conducted, thereby providing some indications in terms of potential risks for the cabin occupants.

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On the influence of gravity on particle accumulation structures in high aspect-ratio liquid bridges

Abstract: Abstract

Cited by 17 publications

References 64 publications

An Investigation into the Behavior of Non-Isodense Particles in Chaotic Thermovibrational Flow

An Investigation into the Behavior of Non-Isodense Particles in Chaotic Thermovibrational Flow

On the Propagation of Hydrothermal Waves in a Fluid Layer with Two-Way Coupled Dispersed Solid Particles

Three-dimensional simulation of clouds of multi-disperse evaporating saliva droplets in a train cabin

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