Scattering from a random two‐fluid interface

1975 ◽  
Vol 57 (S1) ◽  
pp. S17-S17
Author(s):  
John A. DeSanto
Keyword(s):  
Fluid Interface ◽  
Two Fluid

Transmission and reflection of a real sound beam at a two‐fluid interface

1989 ◽  
Vol 85 (S1) ◽  
pp. S93-S93
Author(s):  
Jacqueline Naze Tjøtta ◽  
Hans‐Christen Salvesen ◽  
Sigve Tjøtta
Keyword(s):  
Fluid Interface ◽  
Sound Beam ◽  
Two Fluid ◽  
Transmission And Reflection

Buoyancy flow at a two-fluid interface in a porous medium: Analytical studies

1988 ◽  
Vol 24 (4) ◽  
pp. 493-506 ◽  
Author(s):  
Göran Hellström ◽  
Chin-Fu Tsang ◽  
Johan Claesson
Keyword(s):  
Porous Medium ◽  
Fluid Interface ◽  
Buoyancy Flow ◽  
Analytical Studies ◽  
Two Fluid

Two-Fluid Electroosmotic Flow in Microchannels

2008 ◽  
Author(s):  
T. N. Wong ◽  
Y. Gao ◽  
C. Wang ◽  
C. Yang ◽  
N. T. Nguyen ◽  
...  
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Electroosmotic Flow ◽  
Viscosity Ratio ◽  
Experimental Investigations ◽  
Fluid Interface ◽  
Surface Charges ◽  
Interface Position ◽  
Proposed Model ◽  
Two Fluid

This paper presents theoretical and experimental investigations of the pressure-driven two-liquid flow in microchannels with the electroosmosis effect. For a fully developed, steady state, laminar flow of two liquids combined the pressure gradient, electroosmosis and surface charges at the liquid-liquid interface, we have derived analytical solutions that relate the velocity profiles and flow rates to the liquid holdup, the aspect ratio of the microchannel, the viscosity ratio of the two liquids and the externally applied electric field. It was shown that adjusting the externally applied electric field could control the fluid interface position precisely. The prediction from the proposed model compares very well with measured data.

Measurements of liquid film thickness for a droplet at a two-fluid interface

2012 ◽  
Vol 24 (2) ◽  
pp. 022106 ◽  
Author(s):  
G. Oldenziel ◽  
R. Delfos ◽  
J. Westerweel
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Liquid Film Thickness ◽  
Fluid Interface ◽  
Two Fluid

scholarly journals The effect of a low-viscosity near-wall film on bypass transition in boundary layers

2015 ◽  
Vol 772 ◽  
pp. 330-360 ◽  
Author(s):  
Seo Yoon Jung ◽  
Tamer A. Zaki
Keyword(s):  
Boundary Layer ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Transition To Turbulence ◽  
Bypass Transition ◽  
Fluid Interface ◽  
Free Stream Turbulence ◽  
Wall Film ◽  
The Impact ◽  
Two Fluid

Bypass transition in a two-fluid boundary layer is examined using direct numerical simulations (DNSs). A less-viscous wall film is considered and the impact on transition location is evaluated at two different viscosity ratios and free-stream turbulence intensities. The less-viscous wall film absorbs the mean shear from the outer stream, weakens the lift-up mechanism, and alters the disturbance field inside the boundary layer. These effects all favour a delay in the onset of bypass transition. However, the viscosity and mean-shear discontinuities across the two-fluid interface introduce a new mechanism for the generation of wall-normal vorticity in the boundary layer, and can therefore promote transition to turbulence. Conditionally averaged statistics and streak tracking techniques are adopted in order to examine the impact of the wall film on the bypass transition process. It is shown that the weaker amplification of the streaks in the outer fluid can delay breakdown to turbulence, despite the additional disturbance generation at the two-fluid interface. The efficacy of the wall film in delaying transition is demonstrated at moderate level of free-stream turbulence intensity, but is reduced as the turbulence intensity is increased.

scholarly journals Interfacial instability in electrified plane Couette flow

2011 ◽  
Vol 666 ◽  
pp. 155-188 ◽  
Author(s):  
STEFAN MÄHLMANN ◽  
DEMETRIOS T. PAPAGEORGIOU
Keyword(s):  
Electric Field ◽  
Couette Flow ◽  
Fluid Motion ◽  
Interfacial Instability ◽  
Linear Stability Theory ◽  
Parameter Study ◽  
Fluid Interface ◽  
Fluid Approximation ◽  
Vertical Electric Field ◽  
Two Fluid

The dynamics of a plane interface separating two sheared, density and viscosity matched fluids in the vertical gap between parallel plate electrodes are studied computationally. A Couette profile is imposed onto the fluids by moving the rigid plates at equal speeds in opposite directions. In addition, a vertical electric field is applied to the shear flow by impressing a constant voltage difference on the electrodes. The stability of the initially flat interface is a very subtle balance between surface tension, inertia, viscosity and electric field effects. Under unstable conditions, the potential difference in the fluid results in an electrostatic pressure that amplifies disturbance waves on the two-fluid interface at characteristic wave lengths. Various mechanisms determining the growth rate of the most unstable mode are addressed in a systematic parameter study. The applied methodology involves a combination of numerical simulation and analytical work. Linear stability theory is employed to identify unstable parametric conditions of the perturbed Couette flow. Particular attention is given to the effect of the applied electric field on the instability of the perturbed two-fluid interface. The normal mode analyses are followed up by numerical simulations. The applied method relies on solving the governing equations for the fluid mechanics and the electrostatics in a one-fluid approximation by using a finite-volume technique combined with explicit tracking of the evolving interface. The numerical results confirm those of linear theory and, furthermore, reveal a rich array of dynamical behaviour. The elementary fluid instabilities are finger-like structures of interpenetrating fluids. For weakly unstable situations a single fingering instability emerges on the interface. Increasing the growth rates causes the finger to form a drop-like tip region connected by a long thinning fluids neck. Even more striking fluid motion occurs at higher values of the electric field parameter for which multiple fluid branches develop on the interface. For a pair of perfect dielectrics the vertical electric field was found to enhance interfacial motion irrespective of the permittivity ratio, while in leaky dielectrics the electric field can either stabilize or destabilize the interface, depending on the conductivity and permittivity ratio between the fluids.

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