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We conduct a molecular dynamics simulation of an inelastic gas system utilizing an event-driven algorithm combined with a thermostat mechanism. Initially, the kinetic energy of the system experiences a decay before settling into a…

Computational Physics · Physics 2025-02-03 Rameez Farooq Shah , Shikha Kumari , Syed Rashid Ahmad

In this article we consider the 2D Navier-Stokes equations with variable viscosity depending on the vertical position. As our main result we establish linear enhanced dissipation near the non-affine stationary states replacing Couette flow.…

Analysis of PDEs · Mathematics 2021-10-22 Xian Liao , Christian Zillinger

Starting from the Boltzmann equation in the relaxation time approximation and employing a Chapman-Enskog like expansion for the distribution function close to equilibrium, we derive second-order evolution equations for the shear stress…

Nuclear Theory · Physics 2015-11-18 Amaresh Jaiswal , Bengt Friman , Krzysztof Redlich

The paper is devoted to the study of a new class of optimal control problems for nonsmooth dynamical systems governed by nonconvex discontinuous differential inclusions of the sweeping type with involving variable time into optimization. We…

Optimization and Control · Mathematics 2025-03-05 Tan H. Cao , Boris S. Mordukhovich , Dao Nguyen , Trang Nguyen , Nguyen N. Thieu

In many situations, the combined effect of advection and diffusion greatly increases the rate of convergence to equilibrium -- a phenomenon known as enhanced dissipation. Here we study the situation where the advecting velocity field…

Dynamical Systems · Mathematics 2025-02-11 William Cooperman , Gautam Iyer , Seungjae Son

Discrete element method simulations of confined bidisperse granular shear flows elucidate the balance between diffusion and segregation that can lead to either mixed or segregated states, depending on confining pressure. Results indicate…

Soft Condensed Matter · Physics 2018-09-24 Alexander M. Fry , Paul B. Umbanhowar , Julio M. Ottino , Richard M. Lueptow

The time-dependent surface flux method developed for the description of electronic spectra [L. Tao and A. Scrinzi, New J. Phys. 14, 013021 (2012); A. Scrinzi, New J. Phys. 14, 085008 (2012)] is extended to treat dissociation and…

Atomic Physics · Physics 2014-10-09 Lun Yue , Lars Bojer Madsen

We discuss velocity-jump models for chemotaxis of bacteria with an internal state that allows the velocity jump rate to depend on the memory of the chemoattractant concentration along their path of motion. Using probabilistic techniques, we…

Numerical Analysis · Mathematics 2011-11-23 Mathias Rousset , Giovanni Samaey

Identifying dissipation is essential for understanding the physical mechanisms underlying nonequilibrium processes. {In living systems, for example, the dissipation is directly related to the hydrolysis of fuel molecules such as adenosine…

Statistical Mechanics · Physics 2019-09-02 Ignacio A. Martínez , Gili Bisker , Jordan M. Horowitz , Juan M. R. Parrondo

Nonequilibrium systems, in particular living organisms, are maintained by irreversible transformations of energy that drive diverse functions. Quantifying their irreversibility, as measured by energy dissipation, is essential for…

Statistical Mechanics · Physics 2025-05-21 Qiwei Yu , Pedro E. Harunari

We consider the 2D incompressible Navier-Stokes equations on $\mathbb{T}\times \mathbf{R}$, with initial vorticity that is $\delta$ close in $H^{log}_xL^2_{y}$ to $-1$(the vorticity of the Couette flow $(y,0)$). We prove that if $\delta\ll…

Analysis of PDEs · Mathematics 2019-08-30 Nader Masmoudi , Weiren Zhao

We consider a simple model of the evolution of the concentration of a tracer, subject to a background shear flow by a fluid with viscosity $\nu \ll 1$ in an infinite channel. Taylor observed in the 1950's that, in such a setting, the tracer…

Analysis of PDEs · Mathematics 2015-01-26 Margaret Beck , Osman Chaudhary , C. Eugene Wayne

We study the contribution of advection by thermal velocity fluctuations to the effective diffusion coefficient in a mixture of two indistinguishable fluids. The enhancement of the diffusive transport depends on the system size L and grows…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 A. Donev , A. de la Fuente , J. B. Bell , A. L. Garcia

Bias plays an important role in the enhancement of diffusion in periodic potentials. Using the continuous-time random walk in the presence of a bias, we provide a novel mechanism for the enhancement of diffusion in a random energy…

Statistical Mechanics · Physics 2018-08-15 Takuma Akimoto , Andrey G. Cherstvy , Ralf Metzler

We develop a phase-field model for evaporation from a porous medium by explicitly considering a vapor component together with the liquid and gas phases in the system. The phase-field model consists of the conservation of mass (for phases…

Analysis of PDEs · Mathematics 2024-07-26 Tufan Ghosh , Carina Bringedal , Christian Rohde , Rainer Helmig

A model for axisymmetric magnetized accretion flow is proposed. The dominant mechanism of energy dissipation is assumed to be the magnetic diffusivity due to turbulence in the accretion flow. In analogy to the advection-dominated accretion…

Astrophysics · Physics 2009-11-07 Mohsen Shadmehri

Nonequilibrium, ``fast switching'' estimates of equilibrium free energy differences, Delta F, are often plagued by poor convergence due to dissipation. We propose a method to improve these estimates by generating trajectories with reduced…

Statistical Mechanics · Physics 2009-11-13 Suriyanarayanan Vaikuntanathan , Christopher Jarzynski

In the finite element analysis with fast decoupled time integration scheme for viscoelastic fluid (the Leonov model) flow, we investigate strong nonlinear behavior in 2D creeping contraction flow. The algorithm is applicable in the whole…

Fluid Dynamics · Physics 2011-11-02 Youngdon Kwon

Modelling interfacial dynamics with soluble surfactants in a multiphase system is a challenging task. Here, we consider the numerical approximation of a phase-field surfactant model with fluid flow. The nonlinearly coupled model consists of…

Computational Physics · Physics 2020-03-02 Guangpu Zhu , Jisheng Kou , Shuyu Sun , Jun Yao , Aifen Li

Incompressible flows can be effective mixers by appropriately advecting a passive tracer to produce small filamentation length scales. In addition, diffusion is generally perceived as beneficial to mixing due to its ability to homogenise a…

Fluid Dynamics · Physics 2018-04-20 Christopher J. Miles , Charles R. Doering