We study fluctuating dynamics of a freely movable piston that separates an infinite cylinder into two regions filled with ideal gas particles at the same pressure but different temperatures. To investigate statistical properties time-averaged velocity in long-time limit, we perturbatively calculate large deviation function velocity. Then, derive number effective Langevin equations yielding as o...

Bluff bodies moving in a fluid experience a drag force which usually increases with velocity. However in a particular velocity range a drag crisis is observed, i.e., a sharp and strong decrease of the drag force. This counterintuitive result is well characterized for a sphere or a cylinder. Here we show that, for an object breaking the up-down symmetry, a lift crisis is observed simultaneously ...

[Purpose] The aim of this study was to identify the most effective method of performing ankle pumping exercises. [Subjects and Methods] The study subjects were 10 men. We measured time-averaged maximum flow velocity and peak systolic velocity in the common femoral vein using a pulse Doppler method with a diagnostic ultrasound system during nine ankle pumping exercises (three different ankle pos...

We calculate exactly the modes of motion of the Time-averaged Orbiting Potential (TOP) trap with its four degrees of freedom, namely the three translations and the spin, taken into account. We find that, when gravity is neglected, there are two parameters in the problem namely, the angular velocity of the rotating field and its strength. We present the stability diagram in these parameters. We ...

We study the effect of advection and small diffusion on passive tracers. The advecting velocity field is assumed to have mean zero and to possess time-periodic stream lines. Using a canonical transform to action-angle variables followed by a Lie-transform, we derive an averaged equation describing the effective motion of the tracers. An estimate for the time validity of the first-order approxim...

We describe a quantitative study of vortex generation due to non-equilibrium electrokinetics near a micro/nanochannel interface. The microfluidic device is comprised of a microchannel with a set of nanochannels. These perm-selective nanochannels induce flow instability and thereby produce strong vortex generation. We performed tracking visualization of fluorescent microparticles to obtain veloc...

The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinc...

Measurements by magnetic resonance imaging (MRI) of water flow within granular porous media are presented in this study. Our goal was not only to obtain visualizations of velocity field in porous media but rather to make accurate measurements of interstitial and averaged velocities in bead packs. Two situations were examined: the first for a packed bed with a large beads diameter where it was p...

We present predictions for the statistical error due to finite sampling in the presence of thermal fluctuations in molecular simulation algorithms. Specifically, we establish how these errors depend on Mach number, Knudsen number, number of particles, etc. Expressions for the common hydrodynamic variables of interest such as flow velocity, temperature, density, pressure, shear stress, and heat ...