Shock wave structure in a lattice gas
James E. Broadwell and Donghee Han
The motion and structure of shock and expansion waves in a simple particle system, a lattice gas and cellular automaton, are determined in an exact computation. Shock wave solutions, also exact, of a continuum description, a model Boltzmann equation, are compared with the lattice results. The compar ... [Phys. Fluids 19, 056101 (2007)] published Thu May 3, 2007.
Artificial fluid properties for large-eddy simulation of compressible turbulent mixing
Andrew W. Cook
An alternative methodology is described for large-eddy simulation (LES) of flows involving shocks, turbulence, and mixing. In lieu of filtering the governing equations, it is postulated that the large-scale behavior of a LES fluid, i.e., a fluid with artificial properties, will be similar to that of ... [Phys. Fluids 19, 055103 (2007)] published Thu May 3, 2007.
Optofluidic transport in liquid core waveguiding structures
Sudeep Mandal and David Erickson
Here the authors introduce a method to achieve optofluidically based particle transport using liquid core waveguiding structures. Optically driven transport of 3 [mu]m polystyrene particles through a liquid core photonic crystal fiber is demonstrated and the resulting velocity distribution is chara ... [Appl. Phys. Lett. 90, 184103 (2007)] published Wed May 2, 2007.
Magnetic-field-driven instability in stratified ferrofluids
Andrey Ryskin and Harald Pleiner
We describe a convective instability of a stratified ferrofluid subject to a magnetic field. The ferrofluid is described as binary mixture featuring two important dimensionless numbers the barometric one B and the magnetic barometric one B[sub m]. At the field strength, where the latter exceeds the ... [Phys. Rev. E 75, 056303 (2007)] published Wed May 2, 2007.
The role of helicity and stretching in forced kinematic dynamos in a spherical shell
P. W. Livermore, D. W. Hughes, and S. M. Tobias
Considerations of mean-field theory suggest that small-scale helical flows are an effective means of generating large-scale (mean) magnetic fields, whereas fast dynamo considerations reveal the importance of Lagrangian chaos in the flow for generating small-scale magnetic fields in the limit of high ... [Phys. Fluids 19, 057101 (2007)] published Wed May 2, 2007.
Anisotropic phase-mixing in homogeneous turbulence in a rapidly rotating or in a strongly stratified fluid: An analytical study
A. Salhi and C. Cambon
Angular phase mixing in rapidly rotating or in strongly stratified flows is quantified for single-time single-point energy components, using linear theory. In addition to potential energy, turbulent kinetic energy is more easily analyzed in terms of its toroidal and poloidal components, and then in ... [Phys. Fluids 19, 055102 (2007)] published Tue May 1, 2007.
Laboratory experiments for intense vortical structures in turbulence velocity fields
Hideaki Mouri, Akihiro Hori, and Yoshihide Kawashima
Vortical structures of turbulence, i.e., vortex tubes and sheets, are studied using one-dimensional velocity data obtained in laboratory experiments for duct flows and boundary layers at microscale Reynolds numbers from 332 to 1934. We study the mean velocity profile of intense vortical structures. ... [Phys. Fluids 19, 055101 (2007)] published Tue May 1, 2007.
Dense flows of bidisperse assemblies of disks down an inclined plane
Pierre G. Rognon, Jean-Noel Roux, Mohamed Naaim, and Francois Chevoir
Using discrete numerical simulations, we have studied the flow down a rough inclined plane of a bidisperse assembly of frictional cohesionless disks. Our study focuses on steady uniform flows, once a stable segregation has developed inside the flowing layer. The material is segregated in three layer ... [Phys. Fluids 19, 058101 (2007)] published Tue May 1, 2007.
Streaming potential generated by two-phase flow in a capillary
J. D. Sherwood
The streaming potential generated by pressure-driven two-phase flow in a circular capillary differs from that generated by single-phase flow. Three model problems are considered, in which the dispersed phase consists of either (i) a rigid spherical particle (possibly charged), (ii) an uncharged sphe ... [Phys. Fluids 19, 053101 (2007)] published Tue May 1, 2007.
Salivating Over Chocolate
James L. Throne and Erich Windhab
... [Phys. Today 60, 16 (2007)] published Tue May 1, 2007.
Fractal-like tree networks increasing the permeability
Jun Chen, Boming Yu, Peng Xu, and Yonghua Li
The effective permeability of composites embedded with self-similar fractal-like tree networks is studied. The effective permeability tensor of the composites is derived and is found to be related to microstructures of the networks. The present results show that the larger the ratio of successive br ... [Phys. Rev. E 75, 056301 (2007)] published Tue May 1, 2007.
Scaling laws in the central region of confined turbulent thermal convection
Emily S. C. Ching
In confined turbulent thermal convection, the velocity is separated into two parts: one that is correlated with some function of the temperature fluctuations, and thus associated with the plume velocity, and the other part, the background velocity, which is uncorrelated with any function of the temp ... [Phys. Rev. E 75, 056302 (2007)] published Tue May 1, 2007.
Vortical flow control on a conical fore body cross section using an array of pulsed dc actuators
Kunwar Pal Singh and Subrata Roy
Flow control on a conical fore body cross section of an aircraft is studied using plasma discharge by considering the neutral gas flow at 17.5 deg angle of attack. The equations governing the motion of electrons, ions as well as Poisson's equation are solved together with Navier-Stokes and energy eq ... [J. Appl. Phys. 101, 093301 (2007)] published Tue May 1, 2007.
Ergodicity-breaking and the unraveling dynamics of a polymer in linear and nonlinear extensional flows
Victor A. Beck and Eric S. G. Shaqfeh
We present both theory and simulations describing the unraveling dynamics of polymer chains in linear and nonlinear extensional flows. The nonlinearities associated with the hydrodynamic drag force lead to a conformational hysteresis. This hysteresis can be understood by reducing the problem to ther ... [J. Rheol. 51, 561 (2007)] published Tue May 1, 2007.
Stochastic chain simulation of wall slip in entangled polymer melts
Fang Xu, Morton M. Denn, and Jay D. Schieber
The stochastic chain model described by Xu et al. [J. Rheology [bold 50], 477494 (2006)] provides fundamental insight into the mechanism of apparent wall slip in entangled polymer melts. Apparent slip is shown to be a consequence of a rapid decrease in the entanglement density for chains in the regi ... [J. Rheol. 51, 451 (2007)] published Tue May 1, 2007.
Transient and steady-state solutions of 2D viscoelastic nonisothermal simulation model of film casting process via finite element method
Dong Myeong Shin, Joo Sung Lee, Ju Min Kim, Hyun Wook Jung, and Jae Chun Hyun
The various aspects of the nonlinear dynamics and stability of nonisothermal film casting process have been investigated solving a two-dimensional (2D) viscoelastic simulation model equipped with the Phan-Thien-Tanner (PTT) constitutive equation by employing a finite element method. This study repre ... [J. Rheol. 51, 393 (2007)] published Tue May 1, 2007.
Drop breakup in dilute Newtonian emulsions in simple shear flow: New drop breakup mechanisms
Xinyu Zhao
We investigate drop breakup in dilute Newtonian emulsions in simple shear flow using high-speed video microscopy over a wide range of viscosity ratio (0.0017
Nonlinear viscoelastic properties of branched polyethylene in reversing flows
Changping Sui and Gregory B. McKenna
Two-step reversing flows are severe tests of constitutive equations for polymer melts and have attracted interest for testing the response of branched polymers. Here we report on single-step and three types (types B, C, and D) of reversing torsional flows on branched and linear polyethylenes (PEs). ... [J. Rheol. 51, 341 (2007)] published Tue May 1, 2007.
Dynamic Pipe Stresses During Water Hammer: A Finite Element Approach
Robert A. Leishear
Water hammer is defined as a sudden increase in pipe pressure, which results in pressure waves that travel along the pipe at sonic velocities. In the wake of the pressure wave, dynamic stresses are created in the pipe wall, which contribute to pipe failures. A finite element analysis computer progra ... [J. Pressure Vessel Technol. 129, 226 (2007)] published Tue May 1, 2007.
Influence of wettability conditions on slow evaporation in two-dimensional porous media
O. Chapuis and M. Prat
We study numerically the influence of the wettability condition on slow evaporation in two-dimensional pore square networks of aspect ratio 1. We show how evaporation in a hydrophobic network can be simulated numerically by combining imbibition rules and the computation of diffusion transport in the ... [Phys. Rev. E 75, 046311 (2007)] published Mon Apr 30, 2007.
Gas-liquid two-phase flow across a bank of micropillars
Santosh Krishnamurthy and Yoav Peles
Adiabatic nitrogen-water two-phase flow across a bank of staggered circular micropillars, 100 [mu]m long with a diameter of 100 [mu]m and a pitch-to-diameter ratio of 1.5, was investigated experimentally for Reynolds number ranging from 5 to 50. Flow patterns, void fraction, and pressure drop were ... [Phys. Fluids 19, 043302 (2007)] published Mon Apr 30, 2007.
Quantitative numerical and experimental studies of the shock accelerated heterogeneous bubbles motion
G. Layes and O. Le Metayer
This work deals with quantitative comparisons between experimental and numerical results for shock-bubbles interactions. The bubbles are filled with three different gases (nitrogen, krypton and helium) surrounded by air in order to investigate all kind of density jumps across the interface. For each ... [Phys. Fluids 19, 042105 (2007)] published Mon Apr 30, 2007.
Caging Dynamics in a Granular Fluid
P. M. Reis, R. A. Ingale, and M. D. Shattuck
We report an experimental investigation of the caging motion in a uniformly heated granular fluid for a wide range of filling fractions, phi. At low phi the classic diffusive behavior of a fluid is observed. However, as phi is increased, temporary cages develop and particles become increasingly trap ... [Phys. Rev. Lett. 98, 188301 (2007)] published Mon Apr 30, 2007.
A regime diagram for premixed flame kernel-vortex interactions
Tarek Echekki and Hemanth Kolera-Gokula
Direct numerical simulations of flame kernel-vortex interactions are implemented in an axisymmetric configuration using a two-step global mechanism to study the different combustion regimes of the interactions. Four combustion regimes have been identified. They include: (1) the laminar kernel regime ... [Phys. Fluids 19, 043604 (2007)] published Fri Apr 27, 2007.
Self-similar two-particle separation model
Beat Luthi, Jacob Berg, Soren Ott, and Jakob Mann
We present a new stochastic model for relative two-particle separation in turbulence. Inspired by material line stretching, we suggest that a similar process also occurs beyond the viscous range, with time scaling according to the longitudinal second-order structure function S[sub 2](r), e.g.; in th ... [Phys. Fluids 19, 045110 (2007)] published Fri Apr 27, 2007.
Shock patterns in a slightly underexpanded sonic jet controlled by radial injections
Nicolas Chauvet, Sebastien Deck, and Laurent Jacquin
This Brief Communication is focused on the shock patterns appearing in supersonic round jets subjected to azimuthal disturbances, such as those produced by discrete radial injections. First, it is highlighted that slightly underexpanded sonic jets exhibit a lens-shaped shock wave that is clearly dif ... [Phys. Fluids 19, 048104 (2007)] published Fri Apr 27, 2007.
Cornered drops and rivulets
J. H. Snoeijer, N. Le Grand-Piteira, L. Limat, H. A. Stone, and J. Eggers
We present theoretical and experimental results for a drop of viscous liquid running down an inclined plane at speed U. For U>U[sub cr] the rear of the drop forms a corner whose opening half-angle phi decreases with U. By matching the interior of the drop to the contact line, we calculate phi analyt ... [Phys. Fluids 19, 042104 (2007)] published Fri Apr 27, 2007.
Experimental study of the formation and scaling of a round synthetic jet
Jennifer M. Shuster and Douglas R. Smith
The flow field from a piston-cylinder synthetic jet actuator was investigated in detail over a range of dimensionless stroke values, L[sub [convolution]]/D[sub [convolution]], and Reynolds numbers, Re[sub U[sub [convolution]]]. In each of the test flows examined, only one of these dimensionless grou ... [Phys. Fluids 19, 045109 (2007)] published Fri Apr 27, 2007.
Is plane-channel flow a friendly case for the testing of large-eddy simulation subgrid-scale models?
Johan Meyers and Pierre Sagaut
We present the grid-convergence behavior of channel-flow direct numerical simulations (DNS) at coarse resolutions typically encountered in large-eddy simulation subgrid-model testing. An energy-conservative discretization method is used to systematically vary the streamwise (N[sub x]) and spanwise ( ... [Phys. Fluids 19, 048105 (2007)] published Fri Apr 27, 2007.
Heart-shaped bubbles rising in anisotropic liquids
Chunfeng Zhou, Pengtao Yue, James J. Feng, Chun Liu, and Jie Shen
This Letter reports on numerical simulations motivated by experimental observations of an unusual inverted-heart shape for bubbles rising in an anisotropic micellar solution. We explain the bubble shape by assuming that the micelles are aligned into a nematic phase, whose anchoring energy on the bub ... [Phys. Fluids 19, 041703 (2007)] published Fri Apr 27, 2007.
Wetting condition in diffuse interface simulations of contact line motion
Hang Ding and Peter D. M. Spelt
We investigate the wetting condition for diffuse-interface methods in the simulation of two-fluid flows with moving contact lines. A current method, which uses a surface-energy approach, is shown not to result in a slope of the interface that is consistent with the prescribed value of the contact an ... [Phys. Rev. E 75, 046708 (2007)] published Fri Apr 27, 2007.
Association of Plasma Viscosity with Cardiovascular Risk Factors in Obesity: As an old marker, a new insight
Ercan Meltem, Konukoglu Dildar, and Yesim Erdem Tijen
Although obesity is related with cardiovascular disease, the exact mechanism of the relationship is not fully understood. We aim to examine the relationship between plasma viscosity and obesity as a cardiovascular disease risk factor in obese and non-obese groups. We recruited 75 obese subjects who ... [AIP Conf. Proc. 899, 810 (2007)] published Fri Apr 27, 2007.
Flow And Mass Transfer On A Vertical Half-Immersed Rotating Disk
Nicolas Roche and Krassimir B. Radev
The aim of this study is to predict the liquid film thickness distribution and mass transfer of a weakly soluble gas into a film remaining on a vertical half-immersed rotating disk. (C)2007 American Institute of Physics ... [AIP Conf. Proc. 899, 800 (2007)] published Fri Apr 27, 2007.
Longitudinal Dispersion In Non-Newtonian Laminar Pipe Flow
Terence Cappadoro and Krassimir B. Radev
A theory of the longitudinal dispersion of dynamically passive substance (Taylor's problem) for the case of laminar flow of power-law fluid in circular tube is build involving a treatment of the mass flux evolution. (C)2007 American Institute of Physics ... [AIP Conf. Proc. 899, 768 (2007)] published Fri Apr 27, 2007.
Simulating and Examination of the Separation Nozzle stage performance with rotating wall
Mehdi S. Barough, M. Rahgoshay, A. Abaspour, A. Hogabri, and M. Ghorannevis
In design of the separation Nozzle stage, picked one stage and formulated physical and bulk properties input gas. Then, separation factor (alpha) is calculated and optimized. Optimum UF[sub 6] cut (theta) is 0.25. Two type light auxiliary gas (Hydrogen & Helium) used for acceleration input gas (Hydr ... [AIP Conf. Proc. 899, 646 (2007)] published Fri Apr 27, 2007.
Hydrodynamic Fluctuations And Transversal Dynamics Of A Meniscus In Advance
Krassimir Borissov Radev
Transversal instability of a liquid meniscus, formed in a narrow gap between two immiscible fluids, while advancing in a normal to the interface direction, is concerned. A hydrodynamic model of the spatiotemporal evolution of the meniscus is developed. The analysis of the obtained non-linear equatio ... [AIP Conf. Proc. 899, 457 (2007)] published Fri Apr 27, 2007.
Convergence of Convectively Filtered Burgers Equation to the Entropy Solution of Inviscid Burgers Equation. (arXiv:0805.2176v1 [physics.flu-dyn])
ePrint arXiv http://arXiv.org/
On the decrease of intermittency in decaying rotating turbulence. (arXiv:0805.2182v1 [physics.flu-dyn])
ePrint arXiv http://arXiv.org/
Superfluid spherical Couette flow. (arXiv:0805.2061v1 [cond-mat.other] CROSS LISTED)
ePrint arXiv http://arXiv.org/