Complex fluid-dynamical phenomena modeled by large-scale molecular-dynamics simulations

Alda, Witold; Dzwinel, Witold; Kitowski, Jacek; Mośiński, Jacek; Pogoda, Marek; Yuen, David A.

doi:10.1063/1.168741

Cited by 18 publications

(16 citation statements)

References 24 publications

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“…Recently there has been progress in simulating large systems with 10 000-10 000 000 discrete particles forming an interface [7][8][9][10]. In particular, the microscopic origin of the Rayleigh-Taylor instability was explored in huge molecular dynamics [7,9,10] and direct numerical [8] computer simulations. A natural question concerns the applicability of coarse-grained hydrodynamics to microscopic spatial dimensions.…”

Section: Introductionmentioning

confidence: 99%

“…To the best of our knowledge, for Brownian fluids nothing is known about the onset of the RayleighTaylor instability on a length scale of interparticle distances. Clearly, it will be qualitatively different from the molecular dynamics case where heat will be generated and inertia effects can lead to turbulence [7,9,10]. Mixtures of colloids and polymers, with a real-space analysis of the colloid trajectories, represent a valuable system in which to look at interfacial instabilities for Brownian particles in external driving fields [14].…”

Section: Introductionmentioning

confidence: 99%

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Instability of a fluid–fluid interface in driven colloidal mixtures

Wysocki¹,

Löwen²

2004

J. Phys.: Condens. Matter

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A Rayleigh-Taylor-like interface instability is studied in a compressible Brownian Yukawa fluid mixture on the 'molecular' scales of length and time of the individual particles. As a model, a two-dimensional phase-separated symmetric binary mixture of colloidal particles of type A and B with a fluidfluid interface separating an A-rich phase from a B-rich phase is investigated, by means of Brownian computer simulations, when brought into non-equilibrium via a constant external driving field which acts differently on the different particles and perpendicular to the interface. Two different scenarios are observed which occur either for high or for low interfacial free energies as compared to the driving force. In the first scenario for high interfacial tension, the critical wavelength λ c of the unstable interface modes is in good agreement with the classical Rayleigh-Taylor formula provided that dynamically rescaled values for the interfacial tension are used. The wavelength λ c increases with time, representing an effect of self-healing of the interface due to a local density increase near the interface. The Rayleigh-Taylor formula is confirmed even if λ c is of the order of a molecular correlation length. In the second scenario for very large driving forces as compared to the interfacial line tensions,on the other hand, the particles penetrate the interface easily due to the driving field and form microscopic lanes with a width different from the predictions of the classical Rayleigh-Taylor formula. The results are of relevance for phase-separating colloidal mixtures in a gravitational or electric field.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Instability of a fluid–fluid interface in driven colloidal mixtures

Wysocki¹,

Löwen²

2004

J. Phys.: Condens. Matter

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“…Our results on interface dynamics simulation in Rayleigh-Taylor mixing, using both pure MD technique and the DPD paradigm, were presented in (29)(30)(31).…”

Section: Fig 11mentioning

confidence: 99%

A Two-Level, Discrete-Particle Approach for Simulating Ordered Colloidal Structures

Dzwinel

Yuen

2000

Journal of Colloid and Interface Science

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“…We define [21] the immiscibility factor to be ∆P=P 1 -P 1,2 where P 1 =P 2 are the partial pressures in fluid 1 and 2 respectively. The value of P 1,2 denotes the pressure computed from Eq.…”

Section: Phase Separationmentioning

confidence: 99%

“…molecular dynamics (MD), used in in large-scale simulations [1][2][3][4][5][6][7], 2. finite element methods (FEM), employed in direct numerical simulations (DNS) [8][9][10], are still too demanding and, in many cases, they are not adequate for resolving fine enough features at the mesoscale.…”

Section: Introductionmentioning

confidence: 99%

Parallel implementation of the fluid particle model for simulating complex fluids in the mesoscale

Boryczko

Dzwinel

Yuen

2002

Concurrency and Computation

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Dissipative particle dynamics (DPD) and its generalization -the fluid particle model (FPM) -represent the "fluid particle" approach for simulating fluid-like behavior in the mesoscale. Unlike particles from molecular dynamics (MD) method, the "fluid particle" can be viewed as a "droplet" consisting of liquid molecules. In FPM, "fluid particles" interact by both central and non-central, short-range forces with conservative, dissipative and Brownian character. In comparison to MD, FPM method in 3-D requires two to three times more memory load and three times more communication overhead. Computational load per step per particle is comparable to MD due to the shorter interaction range allowed between "fluid particles" than between MD atoms. The classical linked-cells technique and decomposing the computational box into strips allow for rapid modifications of the code and for implementing non-cubic computational boxes. We show that the efficiency of the FPM code depends strongly on the number of particles simulated, geometry of the box, and the computer architecture. We give a few examples from long FPM simulations involving up to 8 million fluid particles and 32 processors. Results from FPM simulations in 3-D of the phase separation in binary fluid and dispersion of colloidal slab are presented.Scaling law for symmetric quench in phase separation has been properly reconstructed. We show also that the microstructure of dispersed fluid depends strongly on the contrast between kinematic viscosities of this fluid phase and the bulk phase. This FPM code can be applied for simulating mesoscopic flow dynamics in capillary pipes or critical flow phenomena in narrow blood vessels.

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Complex fluid-dynamical phenomena modeled by large-scale molecular-dynamics simulations

Cited by 18 publications

References 24 publications

Instability of a fluid–fluid interface in driven colloidal mixtures

Instability of a fluid–fluid interface in driven colloidal mixtures

A Two-Level, Discrete-Particle Approach for Simulating Ordered Colloidal Structures

Parallel implementation of the fluid particle model for simulating complex fluids in the mesoscale

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