arXiv subjects

Adriano Grigolo

Publications and source records attributed to Adriano Grigolo.

5 recordsLinked to original sources

arXiv2021

Slippery-Sticky Transition of Interfacial Fluid Slip

The influence of temperature on interfacial fluid slip, as measured by molecular-dynamics simulations of a Couette flow comprising a Lennard-Jones fluid and rigid crystalline walls, is examined as a function of the fluid-solid interaction strength. Two different types of thermal behavior are observed, namely, the slippery and sticky cases. The first is characterized by a steep and unlimited increase of the slip length at low temperatures, while the second presents a vanishing slip length in this regime. As the temperature increases in relation to a characteristic value, both cases converge to finite slip lengths. A recently proposed analytical model is found to well describe both thermal behaviors, also predicting the slippery-sticky transition that occurs at a critical value of the fluid-solid interaction parameter, for which, according to the model, fluid particles experience a smooth average energy landscape at the interface.

physics.flu-dyn↗

arXiv2019

Multiscale Approach to Fluid-Solid Interfaces: An overview of methodologies coupling fluid mechanics to molecular dynamics and quantum theory

In conventional fluid mechanics, the chemical composition and thermodynamic state of a fluid-solid interface are not considered when establishing velocity-field boundary conditions. As a consequence, fluid simulations are usually not able to generate different outputs when interfacial materials are varied. By considering an atomistic description of matter, theoretical determination of material-specific boundary conditions becomes possible, thereby providing an improved alternative to the completely-invariant no-slip condition. Such a scheme constitutes a multiscale approach to fluid dynamics involving essentially two transitions between space-time scales: the first concerns the derivation of macroscopic boundary conditions by means of molecular assessment of slip lengths; the second concerns the construction of interatomic force fields, required by molecular dynamics simulations, from quantum theory. In this introductory overview we discuss some of the fundamental aspects of these problems.

physics.flu-dyn↗

arXiv2016

Multiconfigurational quantum propagation with trajectory-guided generalized coherent states

A generalized version of the coupled coherent states method for coherent states of arbitrary Lie groups is developed. In contrast to the original formulation, which is restricted to frozen-Gaussian basis sets, the extended method is suitable for propagating quantum states of systems featuring diversified physical properties, such as spin degrees of freedom or particle indistinguishability. The approach is illustrated with simple models for interacting bosons trapped in double- and triple-well potentials, most adequately described in terms of SU(2) and SU(3) bosonic coherent states, respectively.

quant-ph↗

arXiv2015

Semiclassical Propagator in the Generalized Coherent-State Representation

A detailed derivation of the semiclassical propagator in the generalized coherent-state representation is performed by applying the saddle-point method to a path integral over the classical phase space. With the purpose of providing greater accessibility and applicability to the developed formalism, a brief review of the generalized concept of coherent states is presented, in which three examples of coherent-state sets are examined, namely, the canonical, spin, and SU(n) bosonic coherent states.

quant-ph↗

arXiv2009

An Initial Value Representation with Complex Trajectories

We present an Initial Value Representation for the semiclassical coherent state propagator based on complex trajectories. We map the complex phase space into a real phase space with twice as many dimensions and use a simple procedure to automatically eliminate non-contributing trajectories. The resulting semiclassical formulas do not show divergences due to caustics and provide accurate results.

quant-ph↗