Simulation of Droplet Evaporation in Supercritical Environments Using Parallel Molecular Dynamics
Simulation of Droplet Evaporation in Supercritical Environments Using Parallel Molecular Dynamics

Author:

Publisher:

Published: 1996

Total Pages: 169

ISBN-13:

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The complete evaporation of three-dimensional submicron droplets under both subcritical and supercritical conditions has been modeled using molecular dynamics (MD). This work represents a first step toward an accurate analytical modeling of combustion in supercritical environments. In this initial study the two-phase simulations consist entirely of argon atoms distributed between a single droplet and its surrounding vapor. The inter-atomic forces are based on a Lennard-Jones 12-6 potential, and the resultant atomic displacements are determined using a modified velocity Verlet algorithm. Linked cell lists in combination with Verlet neighbor lists allow efficient modeling of the large and diverse simulations. A non-cubic periodic boundary, specifically a truncated octahedron, is used to minimize periodicity effects. A unique method, using the linked cell structure, streamlines the associated boundary computations. The linked cells are also used as domains for density, temperature and surface tension computations. This allows a contouring of these properties. The surface tension measure is a unique development. p7.

Molecular Dynamics Simulation
Molecular Dynamics Simulation

Author: Kun Zhou

Publisher: Academic Press

Published: 2022-02-10

Total Pages: 375

ISBN-13: 0128166169

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Molecular Dynamic Simulation: Fundamentals and Applications explains the basic principles of MD simulation and explores its recent developments and roles in advanced modeling approaches. The implementation of MD simulation and its application to various aspects of materials science and engineering including mechanical, thermal, mass transportation, and physical/chemical reaction problems are illustrated. Innovative modeling techniques that apply MD to explore the mechanics of typical nanomaterials and nanostructures and to characterize crystalline, amorphous, and liquid systems are also presented. The rich research experience of the authors in MD simulation will ensure that the readers are provided with both an in-depth understanding of MD simulation and clear technical guidance. Provides a comprehensive overview of the underlying theories of molecular dynamics (MD) simulation Presents application-based examples pertaining to a broad range of mechanical, thermal, and mass transport problems Explores innovative modeling techniques for simulating typical nanomaterials and nanostructures and for characterizing crystalline, amorphous, and liquid systems

Droplets and Sprays: Simple Models of Complex Processes
Droplets and Sprays: Simple Models of Complex Processes

Author: Sergei S. Sazhin

Publisher: Springer Nature

Published: 2022-06-28

Total Pages: 603

ISBN-13: 3030997464

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This book acts as a guide to simple models that describe some of the complex fluid dynamics, heat/mass transfer and combustion processes in droplets and sprays. Attention is focused mainly on the use of classical hydrodynamics, and a combination of kinetic and hydrodynamic models, to analyse the heating and evaporation of mono- and multi-component droplets. The models were developed for cases when small and large numbers of components are present in droplets. Some of these models are used for the prediction of time to puffing/micro-explosion of composite water/fuel droplets — processes that are widely used in combustion devices to stimulate disintegration of relatively large droplets into smaller ones. The predictions of numerical codes based on these models are validated against experimental results where possible. In most of the models, droplets are assumed to be spherical; some preliminary results of the generalisation of these models to the case of non-spherical droplets, approximating them as spheroids, are presented.

Evaporative Cooling of Microscopic Water Droplets in Vacuo
Evaporative Cooling of Microscopic Water Droplets in Vacuo

Author:

Publisher:

Published: 2016

Total Pages:

ISBN-13:

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In the present study, we investigate the process of evaporative cooling of nanometer-sized droplets in vacuum using molecular dynamics simulations with the TIP4P/2005 water model. The results are compared to the temperature evolution calculated from the Knudsen theory of evaporation which is derived from kinetic gas theory. The calculated and simulation results are found to be in very good agreement for an evaporation coefficient equal to unity. Lastly, our results are of interest to experiments utilizing droplet dispensers as well as to cloud micro-physics.

Non-equilibrium Thermodynamics of Heterogeneous Systems
Non-equilibrium Thermodynamics of Heterogeneous Systems

Author: Signe Kjelstrup

Publisher: World Scientific

Published: 2008

Total Pages: 451

ISBN-13: 9812779132

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The purpose of this book is to encourage the use of non-equilibrium thermodynamics to describe transport in complex, heterogeneous media. With large coupling effects between the transport of heat, mass, charge and chemical reactions at surfaces, it is important to know how one should properly integrate across systems where different phases are in contact. No other book gives a prescription of how to set up flux equations for transports across heterogeneous systems.The authors apply the thermodynamic description in terms of excess densities, developed by Gibbs for equilibrium, to non-equilibrium systems. The treatment is restricted to transport into and through the surface. Using local equilibrium together with the balance equations for the surface, expressions for the excess entropy production of the surface and of the contact line are derived. Many examples are given to illustrate how the theory can be applied to coupled transport of mass, heat, charge and chemical reactions; in phase transitions, at electrode surfaces and in fuel cells. Molecular simulations and analytical studies are used to add insight.

Fluid Dynamics and Transport of Droplets and Sprays
Fluid Dynamics and Transport of Droplets and Sprays

Author: W. A. Sirignano

Publisher: Cambridge University Press

Published: 2010-01-11

Total Pages: 481

ISBN-13: 0521884896

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This book discusses the theoretical foundations of spray and droplet applications relevant to the technology for active control of sprays applied to new products and applications, improved product performance, cost reductions, and improved environmental outcomes. It also covers theory related to power and propulsion; materials processing and manufacturing technologies including droplet-based net form processing, coating, and painting; medication; pesticides and insecticides; and other consumer uses.

Application of Parallel Processing to the Investigation of Supercritical Droplet Evaporation and Combustion Using Molecular Dynamics
Application of Parallel Processing to the Investigation of Supercritical Droplet Evaporation and Combustion Using Molecular Dynamics

Author: Michael Micci

Publisher:

Published: 1997

Total Pages: 12

ISBN-13:

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Molecular dynamics (MD) implemented on parallel processors was used to model supercritical droplet phenomena occurring in combustion devices. The use of molecular dynamics allows the modeling of supercritical phenomena without an a priori knowledge of the equation of state or transport properties of the individual components or the mixture. Three-dimensional supercritical oxygen vaporization into gaseous oxygen and helium using two-site Lennard-Jones potentials for the oxygen has been modeled and both the disappearance of surface tension above the critical point and the modification of the critical point for a binary mixture have been observed. A distinct change in droplet morphology was observed when passing through its critical point. The droplet remains spherical as it vaporizes under subcritical conditions but becomes broken and cloud-like when supercritical. Equations of state and transport coefficients for mass, momentum and energy have been calculated for supercritical argon, nitrogen and oxygen which agree with NIST values.