arXiv subjects

Youngkyun Jung

Publications and source records attributed to Youngkyun Jung.

4 recordsLinked to original sources

arXiv2016

Molecular dynamics study on a nonequilibrium motion of a colloidal particle driven by an external torque

We investigate the motion of a colloidal particle driven out of equilibrium by an external torque. We use the molecular dynamics simulation that is alternative to the numerical integration approach based on the Langevin equation and is expected to mimic an experiment more realistically. We choose a heat bath composed of thousands of particles interacting to each other through the Lennard-Jones potential and impose the Langevin thermostat to maintain it in equilibrium. We prepare a single colloidal particle to interact with the particles of the heat bath also by the Lennard-Jones potential while any dissipative force and noise are not employed. We prepare the simulation protocol fit to the overdamped limit in real experiments by increasing the size and mass of the colloidal particle. We study the stochastic properties of the nonequilibrium fluctuations for work and heat produced incessantly in time. We accurately confirm the fluctuation theorem for the work production. We show our results to agree accurately with those from the numerical integration of the Langevin equation.

cond-mat.stat-mech↗

arXiv2007

Velocity Inversion in Nanochannel Flow

The nanoscale cylindrical Couette flow is investigated by means of molecular dynamics simulations, in the case where the inner cylinder is rotating whereas the outer cylinder is at rest. We find that the tangential velocity of the low is inverted when the fluid-wall interaction near the outer cylinder is weak and the fluid density is low. The unusual velocity inversion behavior is shown to be strongly related to the degree of the slip between the fluid and the outer cylinder, which is determined by the presence or absence of the layering of the fluid near the outer wall.

cond-mat.stat-mech↗

arXiv1998

Effect of Long-Range Interactions in the Conserved Kardar-Parisi-Zhang Equation

The conserved Kardar-Parisi-Zhang equation in the presence of long-range nonlinear interactions is studied by the dynamic renormalization group method. The long-range effect produces new fixed points with continuously varying exponents and gives distinct phase transitions, depending on both the long-range interaction strength and the substrate dimension $d$. The long-range interaction makes the surface width less rough than that of the short-range interaction. In particular, the surface becomes a smooth one with a negative roughness exponent at the physical dimension d=2.

cond-mat.stat-mech↗

arXiv1996

Dynamical Renormalization Group Study of a Conserved Surface Growth with Anti-Diffusive and Nonlinear Currents

Based on dynamical renormalization group (RG) calculations to the one-loop order, the surface growth described by a nonlinear stochastic conserved growth equation, {\partial h \over \partial t} = \pm ν_2 \nabla^2 h + λ\nabla \cdot (\nabla h)^3 + η, is studied analytically. The universality class of the growth described by the above equation with +{ν_2} (diffusion) is shown to be the same as that described by the Edwards-Wilkinson (EW) equation (i.e. +ν_2 and λ=0). In contrast our RG recursion relations manifest that the growth described by the above equation with {-ν_2}(anti-diffusion) is an unstable growth and do not reproduce the recent results from a numerical simulation by J. M. Kim [Phys. Rev. E 52, 6267 (1995)].

cond-mat↗