Simulations of liquid nanocylinder breakup with dissipative particle dynamics

Tiwari, Anupam; Reddy, Harinath; Mukhopadhyay, Siddhartha; Abraham, John

doi:10.1103/physreve.78.016305

Cited by 30 publications

(12 citation statements)

References 51 publications

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“…particle packing | contact angle | irrotational flow | jamming T he rupture of a single volume filled with matter to produce two unconnected volumes, a transition between two distinct topologies, plays a fundamental role in a wide range of phenomena from dripping liquids (1,2), to breakup of nano-jets (3)(4)(5), to metal rods pinching off (6), to black-string instabilities in general relativity (7,8). In biological systems, topological transitions are equally fundamental because they govern processes like cell division (9), endocytosis (10), and collapsing bacterial colonies (11).…”

mentioning

confidence: 99%

Droplet formation and scaling in dense suspensions

Miskin

Jaeger

2012

Proc. Natl. Acad. Sci. U.S.A.

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When a dense suspension is squeezed from a nozzle, droplet detachment can occur similar to that of pure liquids. While in pure liquids the process of droplet detachment is well characterized through self-similar profiles and known scaling laws, we show here the simple presence of particles causes suspensions to break up in a new fashion. Using high-speed imaging, we find that detachment of a suspension drop is described by a power law; specifically we find the neck minimum radius, r m , scales like τ 2 3 near breakup at time τ ¼ 0. We demonstrate data collapse in a variety of particle/ liquid combinations, packing fractions, solvent viscosities, and initial conditions. We argue that this scaling is a consequence of particles deforming the neck surface, thereby creating a pressure that is balanced by inertia, and show how it emerges from topological constraints that relate particle configurations with macroscopic Gaussian curvature. This new type of scaling, uniquely enforced by geometry and regulated by the particles, displays memory of its initial conditions, fails to be self-similar, and has implications for the pressure given at generic suspension interfaces.particle packing | contact angle | irrotational flow | jamming T he rupture of a single volume filled with matter to produce two unconnected volumes, a transition between two distinct topologies, plays a fundamental role in a wide range of phenomena from dripping liquids (1, 2), to breakup of nano-jets (3-5), to metal rods pinching off (6), to black-string instabilities in general relativity (7,8). In biological systems, topological transitions are equally fundamental because they govern processes like cell division (9), endocytosis (10), and collapsing bacterial colonies (11).Of these examples, liquid droplet formation is particularly notable because it exhibits many of the exotic features of a topological transition, such as singularities and scaling, while being accessible enough to warrant thorough experimental examination (12-18). The result has been a powerful framework that characterizes the final moments of pure liquid droplet detachments using only the relative strengths of surface tension, viscous dissipation, and inertial stress (1, 2). For these liquids, the initial conditions become irrelevant as the system nears the singular point of snap off. Instead, the material parameters alone assign both a self-similar profile defining the shape of the drop and a power law governing how this shape scales close to the final moments of breaking.The success of self-similarity and scaling approaches has prompted attempts to extend pure liquid analysis to other instances of free surface flows. In many cases, when the boundary stresses originate from surface tension, the framework of pure liquid detachment can be modified successfully and self-similar structures govern the breakup (19-21). However, in some cases the driving force comes from an alternative source, as in the case of bubble pinch-off (22-24), and self-similarity breaks down: To describe detachm...

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confidence: 99%

Droplet formation and scaling in dense suspensions

Miskin

Jaeger

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…As the calculation of the effective wave number does not provide a clear insight into the dynamics of breakup the validity of macroscopic scaling laws at this length scale is explored. Following the work of Tiwari et al [16], in order to assess whether the breakup time of a nanoscale liquid thread can be predicted by macroscopic scaling laws, the value of C from Eq. (29) is estimated (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…An innovative workaround to the high computational requirements of MD is to employ a dissipative particle dynamics (DPD) scheme, which coarse models particles as clusters of atoms or molecules. An implementation of the DPD method has been used to study the stability of jets [15] and cylinders [16] of nanoscale dimensions with exceptional success.…”

Section: Introductionmentioning

confidence: 99%

Rayleigh instability at small length scales

Gopan

Sathian

2014

Phys. Rev. E

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The Rayleigh instability (also called the Plateau-Rayleigh instability) of a nanosized liquid propane thread is investigated using molecular dynamics (MD). The validity of classical predictions at small length scales is verified by comparing the temporal evolution of liquid thread simulated by MD against classical predictions. Previous works have shown that thermal fluctuations become dominant at small length scales. The role and influence of the stochastic nature of thermal fluctuations in determining the instability at small length scale is also investigated. Thermal fluctuations are seen to dominate and accelerate the breakup process only during the last stages of breakup. The simulations also reveal that the breakup profile of nanoscale threads undergo modification due to reorganization of molecules by the evaporation-condensation process.

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“…This paper utilizes a traditional quadratic weighting scheme instead of the weight functions employed by Chen et al 20 The DPD equations of motion are integrated using a modified-Verlet scheme proposed by Groot and Warren, 23 and used in several prior studies. 14,15,20,21,24 The time step ⌬t used to integrate the velocity Verlet algorithm is 0.01. This time step has been selected in accordance with the discussion of choice of time step in Ref.…”

Section: The Dpd Modelmentioning

confidence: 99%

“…13 It has also been utilized to simulate multiphase phenomena at submicron scales, such as the breakup of liquid nanocylinders 14 and liquid nanojets. 15 What makes the method attractive for the problem of interest in this work is that it can also be adapted to simulate complex boundaries.…”

Section: Introductionmentioning

confidence: 99%

Dissipative-particle dynamics simulations of flow over a stationary sphere in compliant channels

Reddy

Abraham

2009

Physics of Fluids

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Dissipative-particle dynamics ͑DPD͒, a particle-based fluid-simulation approach, is employed to simulate isothermal pressure-driven flow across a sphere in compliant cylindrical channels. The sphere is represented by frozen DPD particles, while the surrounding fluid is modeled using simple fluid particles. The channel walls are made up of interconnected finite extensible nonlinear elastic bead-spring chains. The wall particles at the inlet and outlet ends of the channel are frozen so as to hinge the channel. The model is assessed for accuracy by computing the drag coefficient C D in shear flow past a uniform sphere in unbounded flow, and comparing the results with those from correlations in literature. The effect of the aspect ratio of the channel, i.e., the ratio of the sphere diameter d to the channel diameter D, on the drag force F D on the sphere is investigated, and it is found that F D decreases as decreases toward the values predicted by the correlations as approaches zero. The effect of the elasticity of the wall is also studied. It is observed that as the wall becomes more elastic, there is a decrease in F D on the sphere.

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Simulations of liquid nanocylinder breakup with dissipative particle dynamics

Cited by 30 publications

References 51 publications

Droplet formation and scaling in dense suspensions

Droplet formation and scaling in dense suspensions

Rayleigh instability at small length scales

Dissipative-particle dynamics simulations of flow over a stationary sphere in compliant channels

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