Permeability and effective slip in confined flows transverse to wall slippage patterns
The pressure-drivenStokes flow through a plane channel with arbitrary wall separation having a continuouspattern of sinusoidally varying slippage of arbitrary wavelength and amplitude on one/both walls is modelled semi-analytically. Thepatterning direction is transverse to theflow. In the special situations of thin and thick channels, respectively, the predictions of the model are found to be consistent withlubrication theory and results from the literature pertaining to freeshear flow. For the samepattern-averaged slip length, the hydraulic permeability relative to a channel with no-slip walls increases as thepattern wave...
Source: Physics of Fluids - August 1, 2016 Category: Physics Authors: Avinash Kumar, Subhra Datta and Dinesh Kalyanasundaram Source Type: research
Stability of thermal convection in a rotating cylindrical container
The rotation and an axial gradient of temperature drive the meridional circulation of afluid filling a sealed cylindrical container. This numerical study explains why theflow remains stable up to the Grashof numberGr around 1011;Gr characterizes the circulation strength. The shear-layerinstability, occurring in a rotating pipe for small values of the Prandtl numberPr [M. A. Herrada and V. N. Shtern, “Stability of centrifugalconvection in a rotating pipe, ” Phys.Fluids27, 064106 (2015)], is suppressed here even for the cylinder length-to-radius ratio being ten. The cold end disk enhances thefluid circulation near the si...
Source: Physics of Fluids - August 1, 2016 Category: Physics Authors: Miguel Herrada and Vladimir Shtern Source Type: research
Microscopic molecular dynamics characterization of the second-order non-Navier-Fourier constitutive laws in the Poiseuille gas flow
The second-order non-Navier-Fourier constitutive laws, expressed in a compactalgebraic mathematical form, were validated for the force-drivenPoiseuille gasflow by the deterministicatomic-level microscopicmolecular dynamics (MD). Emphasis is placed on how completely different methods (asecond-order continuum macroscopictheory based on the kineticBoltzmann equation, theprobabilistic mesoscopic direct simulation Monte Carlo, and, in particular, thedeterministic microscopic MD) describe the non-classical physics, and whether the second-order non-Navier-Fourier constitutive laws derived from the continuumtheory can be validated...
Source: Physics of Fluids - August 1, 2016 Category: Physics Authors: A. Rana, R. Ravichandran, J. H. Park and R. S. Myong Source Type: research
Nanoflow over a fractal surface
This paper investigates the effects ofsurface roughness onnanoflows usingmolecular dynamics simulations. Afractal model is employed to model wall roughness, and simulations are performed forliquid argon confined by two solid walls. It is shown that thesurface roughness reduces the velocity in the proximity of the walls with the reduction being accentuated when increasing the roughness depth and wettability of the solid wall. It also makes theflow three-dimensional and anisotropic. Inflows over idealized smoothsurfaces, theliquid forms parallel, well-spaced layers, with a significant gap between the first layer and the soli...
Source: Physics of Fluids - August 1, 2016 Category: Physics Authors: Michail Papanikolaou, Michael Frank and Dimitris Drikakis Source Type: research
Fluid mobility over corrugated surfaces in the Stokes regime
Anexact solution is found for laminar fluidflow along the grooves of a family ofsurfaces whose shape is given by the Lambert W-function. This simple solution allows for the slip length in the direction parallel to the grooves to be calculated exactly. With this analytical model, we establish the regime of validity for a previously untestedperturbation theory intended for calculating thesurface mobilitytensor of arbitrary periodicsurfaces, finding that it compares well to the exact expression for nearly all choices of parameters of the conformal map. To test thisperturbation theory further, the mobilitytensor is evaluated f...
Source: Physics of Fluids - August 1, 2016 Category: Physics Authors: S. R. Shelley, J. D. Smith, A. P. Hibbins, J. R. Sambles and S. A. R. Horsley Source Type: research
Comment on “Viscous coalescence of droplets: A lattice Boltzmann study” [Phys. Fluids 25, 052101 (2013)]
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Source: Physics of Fluids - July 28, 2016 Category: Physics Authors: Lina Baroudi, Sidney R. Nagel and Taehun Lee Source Type: research
Response to “Comment on ‘Viscous coalescence of droplets: A lattice Boltzmann study”’ [Phys. Fluids 28, 079101 (2016)]
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Source: Physics of Fluids - July 28, 2016 Category: Physics Authors: M. Gross, I. Steinbach, D. Raabe and F. Varnik Source Type: research
Dielectrophoretic- and electrohydrodynamic-driven translational motion of a liquid column in transverse electric fields
< div > < p > Computer simulations are performed to study translational motion and deformation of a < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > liquid < /span > column or < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > jet, < /span > in a plane perpendicular to its axis, due to a transverse < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > electric field. < /span > A front tracking/finite difference scheme is used in conjunction with the Taylor-Melcher leaky < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="nam...
Source: Physics of Fluids - July 26, 2016 Category: Physics Authors: Asghar Esmaeeli Source Type: research
Energy spectra in elasto-inertial turbulence
< div > < p > Direct numerical simulations of statistically steady homogeneous isotropic turbulence in < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > viscoelastic < /span > fluids described by the FENE-P < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > model < /span > are presented. Emphasis is given to large < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > polymer < /span > < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > relaxation times < /span > compared to the eddy turnover time, which is a ...
Source: Physics of Fluids - July 22, 2016 Category: Physics Authors: P. C. Valente, C. B. da Silva and F. T. Pinho Source Type: research
Origin of particle accumulation structures in liquid bridges: Particle –boundary-interactions versus inertia
< div > < p > The formation of particle-accumulation structures in the < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > flow < /span > in a cylindrical < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > liquid bridge < /span > driven by the thermocapillary effect is studied with the aim of determining the physical mechanism which forms the structures. The < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > flow < /span > is modeled using the incompressible Navier –Stokes and energy equations with the assumption of constant fluid pr...
Source: Physics of Fluids - July 22, 2016 Category: Physics Authors: Frank H. Muldoon and Hendrik C. Kuhlmann Source Type: research
The late time structure of high density contrast, single mode Richtmyer-Meshkov flow
< div > < p > We study the late time flow structure of < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > Richtmyer-Meshkov instability. < /span > Recent numerical work [F. J. Cherne < span class="jp-italic" > et al. < /span > “On shock driven jetting of liquid from non-sinusoidal < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > surfaces < /span > into a vacuum, ” J. Appl. Phys. < span class="jp-bold" > 118 < /span > , 185901 (2015)] has suggested a self-similar collapse of the development of this < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class...
Source: Physics of Fluids - July 22, 2016 Category: Physics Authors: R. J. R. Williams Source Type: research
A numerical model for the evolution of internal structure of cavitation cloud
In this study, a numerical < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > model < /span > was developed to study the evolution of the internal structure of cloud < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > cavitation. < /span > The < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > model < /span > includes (1) an evolution < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > equation < /span > of < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > bubble < /span > < sp...
Source: Physics of Fluids - July 21, 2016 Category: Physics Authors: Tezhuan Du, Yiwei Wang, Lijuan Liao and Chenguang Huang Source Type: research
Numerical simulations of shoaling internal solitary waves of elevation
We present high-resolution, two- and three-dimensional direct numerical simulations of large amplitude internal solitary < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > waves < /span > of elevation on the laboratory scale, shoaling onto and over a small-amplitude shelf. The three-dimensional, mapped coordinate, spectral collocation method used for the simulations allows for accurate modelling of both the shoaling < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > waves < /span > and the bottom boundary layer. The shoaling of the < span xmlns="http://pub2web.met...
Source: Physics of Fluids - July 21, 2016 Category: Physics Authors: Chengzhu Xu, Christopher Subich and Marek Stastna Source Type: research
Radiation forces and torque on a rigid elliptical cylinder in acoustical plane progressive and (quasi)standing waves with arbitrary incidence
< div > < p > This paper presents two key contributions; the first concerns the development of analytical expressions for the axial and transverse acoustic radiation forces exerted on a 2D rigid elliptical cylinder placed in the field of plane progressive, quasi-standing, or standing < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > waves < /span > with arbitrary incidence. The second emphasis is on the acoustic radiation < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > torque < /span > per length. The rigid elliptical cylinder case is important to be considere...
Source: Physics of Fluids - July 21, 2016 Category: Physics Authors: F. G. Mitri Source Type: research
Pinch-off of axisymmetric vortex pairs in the limit of vanishing vortex line curvature
< div > < p > Pinch-off of axisymmetric < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > vortex < /span > pairs generated by < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > flow < /span > between concentric cylinders with radial separation Δ < span class="jp-italic" > R < /span > was studied numerically and compared with planar < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" > vortex < /span > dipole behavior. The axisymmetric case approaches planar < span xmlns="http://pub2web.metastore.ingenta.com/ns/" class="named-content" ...
Source: Physics of Fluids - July 21, 2016 Category: Physics Authors: V. Sadri and P. S. Krueger Source Type: research
