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Guillermo Terrones - One of the best experts on this subject based on the ideXlab platform.
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Fastest growing linear Rayleigh-Taylor modes at solid/fluid and solid/solid Interfaces.
Physical Review E, 2005Co-Authors: Guillermo TerronesAbstract:: Previous linear stability analyses of the Rayleigh-Taylor instability problem for elastic solids have been restricted to calculating the cutoff wavelength lambda(c) (zero growth rate) in the limit of Atwood number A of unity. Here, we rigorously derive the dispersion relations for solid/fluid and solid/solid Interfaces and perform a systematic investigation to compute the most unstable modes (maximum growth rate) for all A. After rationalizing the dispersion relations into multivariable polynomials, we compute the physically meaningful wavelength lambda and growth rate sigma for all unstable disturbances as a function of the mechanical properties of the participating media (shear moduli, dynamic viscosity, and density contrast) and acceleration. It is shown that at these Interfaces, the onset of instability can only arise via monotonically growing disturbances. For solid/fluid and solid/solid Interfaces, the locus of the most unstable wavelength lambda(m) and growth rate sigma(m) pairs are calculated to cover the entire range of behavior in dimensionless space. We find that under certain conditions, at solid/fluid Interfaces, two configurations with distinct A can have the same lambda(m) (a behavior that does not occur at solid/solid Interfaces). In terms of estimating sigma(m), lambda(m), and lambda(c), the applicability of our results extends to layers of finite thickness h provided h > lambda/2. We suggest a plausible mechanism to explain the wavelength selection process in nominally smooth magnetically imploded liners observed in recent experiments.
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Fastest growing linear Rayleigh-Taylor modes at solid/fluid and solid/solid Interfaces.
Physical Review E, 2005Co-Authors: Guillermo TerronesAbstract:Previous linear stability analyses of the Rayleigh-Taylor instability problem for elastic solids have been restricted to calculating the cutoff wavelength ${\ensuremath{\lambda}}_{c}$ (zero growth rate) in the limit of Atwood number $A$ of unity. Here, we rigorously derive the dispersion relations for solid∕fluid and solid∕solid Interfaces and perform a systematic investigation to compute the most unstable modes (maximum growth rate) for all $A$. After rationalizing the dispersion relations into multivariable polynomials, we compute the physically meaningful wavelength $\ensuremath{\lambda}$ and growth rate $\ensuremath{\sigma}$ for all unstable disturbances as a function of the mechanical properties of the participating media (shear moduli, dynamic viscosity, and density contrast) and acceleration. It is shown that at these Interfaces, the onset of instability can only arise via monotonically growing disturbances. For solid∕fluid and solid∕solid Interfaces, the locus of the most unstable wavelength ${\ensuremath{\lambda}}_{m}$ and growth rate ${\ensuremath{\sigma}}_{m}$ pairs are calculated to cover the entire range of behavior in dimensionless space. We find that under certain conditions, at solid∕fluid Interfaces, two configurations with distinct $A$ can have the same ${\ensuremath{\lambda}}_{m}$ (a behavior that does not occur at solid∕solid Interfaces). In terms of estimating ${\ensuremath{\sigma}}_{m},{\ensuremath{\lambda}}_{m}$, and ${\ensuremath{\lambda}}_{c}$, the applicability of our results extends to layers of finite thickness $h$ provided $hg\ensuremath{\lambda}∕2$. We suggest a plausible mechanism to explain the wavelength selection process in nominally smooth magnetically imploded liners observed in recent experiments.
Mukul M. Sharma - One of the best experts on this subject based on the ideXlab platform.
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Geophysics at the interface: Response of geophysical properties to solid‐fluid, fluid‐fluid, and solid‐solid Interfaces
Reviews of Geophysics, 2010Co-Authors: Rosemary Knight, Estella A. Atekwana, Laura J. Pyrak-nolte, Lee Slater, Anthony L. Endres, Jil T. Geller, David P. Lesmes, Seiji Nakagawa, André Revil, Mukul M. SharmaAbstract:Laboratory studies reveal the sensitivity of measured geophysical properties to solid-fluid, fluid-fluid, and Solid-Solid Interfaces in granular and fractured materials. In granular materials, electrical properties and nuclear magnetic resonance relaxation times exhibit a strong dependence on the size and properties of the solid-fluid interface. The electrical and seismic properties of granular materials and the seismic properties of fractured materials reveal a dependence on the size or geometry of fluid-fluid Interfaces. Seismic properties of granular and fractured materials are affected by the effective stress and cementing material at Solid-Solid Interfaces. There have been some recent studies demonstrating the use of field-scale measurements to obtain information about pore-scale Interfaces. In addition, a new approach to geophysical field measurements focuses on the geophysical response of the field-scale interface itself, with successful applications in imaging the water table and a redox front. The observed sensitivity of geophysical data to Interfaces highlights new ways in which geophysical measurements could be used to obtain information about subsurface properties and processes.
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Geophysics at the interface: Response of geophysical properties to solid-fluid, fluid-fluid, and Solid-Solid Interfaces
Reviews of Geophysics, 2010Co-Authors: Rosemary Knight, Estella A. Atekwana, Laura J. Pyrak-nolte, Lee Slater, David P. Lesmes, Seiji Nakagawa, A. Endres, J. Geller, André Revil, Mukul M. SharmaAbstract:Laboratory studies reveal the sensitivity of measured geophysical properties to solid-fluid, fluid-fluid, and Solid-Solid Interfaces in granular and fractured materials. In granular materials, electrical properties and nuclear magnetic resonance relaxation times exhibit a strong dependence on the size and properties of the solid-fluid interface. The electrical and seismic properties of granular materials and the seismic properties of fractured materials reveal a dependence on the size or geometry of fluid-fluid Interfaces. Seismic properties of granular and fractured materials are affected by the effective stress and cementing material at Solid-Solid Interfaces. There have been some recent studies demonstrating the use of field-scale measurements to obtain information about pore-scale Interfaces. In addition, a new approach to geophysical field measurements focuses on the geophysical response of the field-scale interface itself, with successful applications in imaging the water table and a redox front. The observed sensitivity of geophysical data to Interfaces highlights new ways in which geophysical measurements could be used to obtain information about subsurface properties and processes.
Rosemary Knight - One of the best experts on this subject based on the ideXlab platform.
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Geophysics at the interface: Response of geophysical properties to solid‐fluid, fluid‐fluid, and solid‐solid Interfaces
Reviews of Geophysics, 2010Co-Authors: Rosemary Knight, Estella A. Atekwana, Laura J. Pyrak-nolte, Lee Slater, Anthony L. Endres, Jil T. Geller, David P. Lesmes, Seiji Nakagawa, André Revil, Mukul M. SharmaAbstract:Laboratory studies reveal the sensitivity of measured geophysical properties to solid-fluid, fluid-fluid, and Solid-Solid Interfaces in granular and fractured materials. In granular materials, electrical properties and nuclear magnetic resonance relaxation times exhibit a strong dependence on the size and properties of the solid-fluid interface. The electrical and seismic properties of granular materials and the seismic properties of fractured materials reveal a dependence on the size or geometry of fluid-fluid Interfaces. Seismic properties of granular and fractured materials are affected by the effective stress and cementing material at Solid-Solid Interfaces. There have been some recent studies demonstrating the use of field-scale measurements to obtain information about pore-scale Interfaces. In addition, a new approach to geophysical field measurements focuses on the geophysical response of the field-scale interface itself, with successful applications in imaging the water table and a redox front. The observed sensitivity of geophysical data to Interfaces highlights new ways in which geophysical measurements could be used to obtain information about subsurface properties and processes.
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Geophysics at the interface: Response of geophysical properties to solid-fluid, fluid-fluid, and Solid-Solid Interfaces
Reviews of Geophysics, 2010Co-Authors: Rosemary Knight, Estella A. Atekwana, Laura J. Pyrak-nolte, Lee Slater, David P. Lesmes, Seiji Nakagawa, A. Endres, J. Geller, André Revil, Mukul M. SharmaAbstract:Laboratory studies reveal the sensitivity of measured geophysical properties to solid-fluid, fluid-fluid, and Solid-Solid Interfaces in granular and fractured materials. In granular materials, electrical properties and nuclear magnetic resonance relaxation times exhibit a strong dependence on the size and properties of the solid-fluid interface. The electrical and seismic properties of granular materials and the seismic properties of fractured materials reveal a dependence on the size or geometry of fluid-fluid Interfaces. Seismic properties of granular and fractured materials are affected by the effective stress and cementing material at Solid-Solid Interfaces. There have been some recent studies demonstrating the use of field-scale measurements to obtain information about pore-scale Interfaces. In addition, a new approach to geophysical field measurements focuses on the geophysical response of the field-scale interface itself, with successful applications in imaging the water table and a redox front. The observed sensitivity of geophysical data to Interfaces highlights new ways in which geophysical measurements could be used to obtain information about subsurface properties and processes.
Ishwar K. Puri - One of the best experts on this subject based on the ideXlab platform.
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Molecular simulations of thermal transport across Interfaces: solid–vapour and solid–solid
Molecular Simulation, 2012Co-Authors: Sohail Murad, Ishwar K. PuriAbstract:Using molecular simulations, we have investigated heat transfer across the solid–fluid interface between water and silicon and silica wafers, and solid–solid Interfaces in superlattices and thin solid films. The system set-up has allowed us to focus on the resistance associated with both the fluid and solid Interfaces. For instance, by maintaining the solid phase at a constant temperature we can focus solely on the fluid-side resistance. Our results show that the thermal or Kapitza resistance at fluid side of the solid–fluid decreases significantly as the surface is made more hydrophilic. This is primarily due to increases in fluid adsorption and absorption at the surface, which enhance the intermolecular collision frequency at the interface. Increasing this frequency also reduces the dependence of thermal transport on variations in the interfacial temperature and pressure. Hence, decreasing the density diminishes the intermolecular collision frequency, which increases the thermal resistance. By maintaini...
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Multiscale Thermal Transport Across Solid-Solid Interfaces
Volume 4: Electronics and Photonics, 2010Co-Authors: Ganesh Balasubramanian, Ravi Kappiyoor, Ishwar K. PuriAbstract:We propose a novel multiscale model in order to better understand thermal transport across Solid-Solid Interfaces in a mesoscale system. While Molecular Dynamics (MD) simulations tend to be very accurate, they are also computationally rather expensive. Continuum simulations such as Symmetric Smoothed Particle Hydrodynamics (SSPH), cannot take temperature discontinuities that may occur across Interfaces into account, which can cause erroneous results. As such, we develop a multiscale model in which we run MD simulations over the region containing the interface, while running SSPH simulations over the remainder of the domain. This drastically reduces the number of molecules simulated by MD, reducing computational time, while hopefully still maintaining the accuracy provided by a “pure” MD run. Results from the simulation indicate that when boundary temperatures are specified, the data from the multiscale model is highly similar to the data from the pure MD run. However, when boundary fluxes are specified, the multiscale model tends to predict higher temperatures than does MD. We believe that this may be due to continuum SSPH simulations being unable to take into account phonon scattering with non-periodic boundary conditions.Copyright © 2010 by ASME
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Thermal transport through superlattice Solid-Solid Interfaces
Applied Physics Letters, 2009Co-Authors: Sohail Murad, Ishwar K. PuriAbstract:Using molecular dynamics, we consider the thermal resistances of superlattices consisting of varying numbers of distinct nanolayers of two different materials. These are placed between two water reservoirs at uniform hot and cold temperatures. The interfacial resistances produced between different solid layers can lead to significantly lower heat transfer for a specified temperature difference. Such a large reduction in thermal transport cannot be explained by the interfacial resistance alone. In addition to the interfacial resistance between two adjacent superlattice layers, the relatively wide thermal boundary layers that are produced adjacent to the Interfaces introduces a supplementary resistance.
Richard V. Craster - One of the best experts on this subject based on the ideXlab platform.
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Diffusely scattered and transmitted elastic waves by random rough Solid-Solid Interfaces using an elastodynamic Kirchhoff approximation
Physical Review B, 2017Co-Authors: Michael J. S. Lowe, Richard V. CrasterAbstract:Elastic waves scattered by random rough Interfaces separating two distinct media play an important role in modeling phonon scattering and impact upon thermal transport models, and are also integral to ultrasonic inspection. We introduce theoretical formulas for the diffuse field of elastic waves scattered by, and transmitted across, random rough Solid-Solid Interfaces using the elastodynamic Kirchhoff approximation. The new formulas are validated by comparison with numerical Monte Carlo simulations, for a wide range of roughness (rms σ≤λ/3, correlation length λ0≥ wavelength λ), demonstrating a significant improvement over the widely used small-perturbation approach, which is valid only for surfaces with small rms values. Physical analysis using the theoretical formulas derived here demonstrates that increasing the rms value leads to a considerable change of the scattering patterns for each mode. The roughness has different effects on the reflection and the transmission, with a strong dependence on the material properties. In the special case of a perfect match of the wave speed of the two solid media, the transmission is the same as the case for a flat interface. We pay particular attention to scattering in the specular direction, often used as an observable quantity, in terms of the roughness parameters, showing a peak at an intermediate value of rms; this rms value coincides with that predicted by the Rayleigh parameter
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Diffusely scattered and transmitted elastic waves by random rough Solid-Solid Interfaces using an elastodynamic Kirchhoff approximation
Physical Review B, 2017Co-Authors: Fan Shi, Michael J. S. Lowe, Richard V. CrasterAbstract:Elastic waves scattered by random rough Interfaces separating two distinct media play an important role in modeling phonon scattering and impact upon thermal transport models, and are also integral to ultrasonic inspection. We introduce theoretical formulas for the diffuse field of elastic waves scattered by, and transmitted across, random rough Solid-Solid Interfaces using the elastodynamic Kirchhoff approximation. The new formulas are validated by comparison with numerical Monte Carlo simulations, for a wide range of roughness (rms $\ensuremath{\sigma}\ensuremath{\le}\ensuremath{\lambda}/3$, correlation length ${\ensuremath{\lambda}}_{0}\ensuremath{\ge}$ wavelength $\ensuremath{\lambda}$), demonstrating a significant improvement over the widely used small-perturbation approach, which is valid only for surfaces with small rms values. Physical analysis using the theoretical formulas derived here demonstrates that increasing the rms value leads to a considerable change of the scattering patterns for each mode. The roughness has different effects on the reflection and the transmission, with a strong dependence on the material properties. In the special case of a perfect match of the wave speed of the two solid media, the transmission is the same as the case for a flat interface. We pay particular attention to scattering in the specular direction, often used as an observable quantity, in terms of the roughness parameters, showing a peak at an intermediate value of rms; this rms value coincides with that predicted by the Rayleigh parameter.