scholarly journals Effective Interfacial Tension Effect on Kelvin-Helmholtz Instability

2020 ◽  
pp. 122-128
Author(s):  
Pardeep Kumar ◽  
Hari Mohan
Keyword(s):  
Interfacial Tension ◽  
Wave Number ◽  
Stable Configuration ◽  
Helmholtz Instability ◽  
Stability Range ◽  
Number Range ◽  
Wave Number Range ◽  
Medium Porosity ◽  
The Stability ◽  
Special Case

The instability of the plane interface between two uniform, superposed and streaming Walters′ B′ viscoelastic fluids through porous medium in the presence of effective interfacial tension is considered. The case of two uniform streaming fluids separated by a horizontal boundary is studied. It is observed, for the special case where the effective interfacial tension is ignored, that the system is stable or unstable for the potentially stable configuration which is in contrast to the case of Rivlin-Ericksen viscoelastic fluid or Newtonian fluid where the system is always stable for the potentially stable configuration. Moreover, if the perturbations in the direction of streaming are ignored, then the perturbations transverse to the direction of streaming are found to be unaffected by the presence of streaming, whereas for perturbations in all other directions there exists instability for a certain wave number range. ‘Effective interfacial tension’ is able to suppress this Kelvin-Helmholtz instability for small wavelength perturbations, the medium porosity reduces the stability range given in terms of a difference in streaming velocities.

scholarly journals Effective interfacial tension effect on the instability of streaming Rivlin-Ericksen elastico-viscous fluid flow through a porous medium

2016 ◽  
Vol 21 (1) ◽  
pp. 221-229
Author(s):  
M. Singh
Keyword(s):  
Interfacial Tension ◽  
Viscous Fluids ◽  
Wave Number ◽  
Helmholtz Instability ◽  
Stability Range ◽  
Number Range ◽  
Wave Number Range ◽  
Medium Porosity ◽  
Flow Through ◽  
The Stability

Abstract The instability of the plane interface between two uniform, superposed and streaming Rivlin-Ericksen elastico-viscous fluids through porous media, including the ‘effective interfacial tension’ effect, is considered. In the absence of the ‘effective interfacial tension’ stability/instability of the system as well as perturbations transverse to the direction of streaming are found to be unaffected by the presence of streaming if perturbations in the direction of streaming are ignored, whereas for perturbation in all other directions, there exists instability for a certain wave number range. The ‘effective interfacial tension’ is able to suppress this Kelvin-Helmholtz instability for small wavelength perturbations, the medium porosity reduces the stability range given in terms of a difference in streaming velocities.

Hydromagnetic Stability of Two Rivlin-Ericksen Elastico-Viscous Superposed Conducting Fluids

1997 ◽  
Vol 52 (6-7) ◽  
pp. 528-532
Author(s):  
R. C. Sharma ◽  
P. Kumar
Keyword(s):  
Magnetic Field ◽  
Wave Number ◽  
Horizontal Magnetic Field ◽  
Number Range ◽  
Wave Number Range ◽  
Unstable Configuration ◽  
The Stability ◽  
Superposed Fluids ◽  
The Magnetic Field ◽  
Conducting Fluids

Abstract The stability of the plane interface separating two Rivlin-Ericksen elastico-viscous superposed fluids of uniform densities when the whole system is immersed in a uniform horizontal magnetic field has been studied. The stability analysis has been carried out, for mathematical simplicity, for two highly viscous fluids of equal kinematic viscosities and equal kinematic viscoelasticities. It is found that the stability criterion is independent of the effects of viscosity and viscoelasticity and is dependent on the orientation and magnitude of the magnetic field. The magnetic field is found to stabilize a certain wave-number range of the unstable configuration. The behaviour of growth rates with respect to kinematic viscosity and kinematic viscoelasticity parameters are examined numerically.

The instability of streaming fluids in a porous medium

1982 ◽  
Vol 60 (10) ◽  
pp. 1391-1395 ◽  
Author(s):  
R. C. Sharma ◽  
T. J. T. Spanos
Keyword(s):  
Surface Tension ◽  
Porous Medium ◽  
Porous Media ◽  
Plane Interface ◽  
Helmholtz Instability ◽  
Stability Range ◽  
Wavenumber Range ◽  
Medium Porosity ◽  
The Stability

The instability of the plane interface between two uniform, superposed, and streaming fluids through porous media is considered. The configuration is taken to be bottom-heavy. In the absence of surface tension, perturbations transverse to the direction of streaming are found to be unaffected by the presence of streaming if perturbation in the direction of streaming are ignored, whereas for perturbations in all other directions there exists instability for a certain wavenumber range. The surface tension is able to suppress this Kelvin–Helmholtz instability for small wavelength perturbations and the medium porosity reduces the stability range given in terms of a difference in streaming velocities. For the top-heavy configurations, the surface tension stabilizes a certain wavenumber range.

Taylor instability of finite surface waves

1960 ◽  
Vol 7 (2) ◽  
pp. 177-193 ◽  
Author(s):  
H. W. Emmons ◽  
C. T. Chang ◽  
B. C. Watson
Keyword(s):  
Order Theory ◽  
Transition To Turbulence ◽  
Wave Number ◽  
Helmholtz Instability ◽  
Third Order ◽  
Number Range ◽  
Jet Instability ◽  
Stages Of Growth ◽  
Wave Number Range ◽  
Theoretical Results

The instability of the accelerated interface between a liquid (methanol or carbon tetrachloride) and air has been investigated experimentally for approximate sinusoidal disturbances of wave-number range from well below to well above the cut-off. The growth rates are measured and compared with theoretical results. A third-order theory shows the phenomena of overstability which is found in the experimental results. Some measurements of later stages of growth agree moderately well with the available theory and disclose some additional phenomena of bubble competition, Helmholtz instability with transition to turbulence, and jet instability with production of drops.

scholarly journals Instability through porous medium of two viscous superposed conducting fluids

1982 ◽  
Vol 5 (2) ◽  
pp. 365-375 ◽  
Author(s):  
R. C. Sharma ◽  
K. P. Thakur
Keyword(s):  
Magnetic Field ◽  
Porous Medium ◽  
Wave Number ◽  
Horizontal Magnetic Field ◽  
Number Range ◽  
Wave Number Range ◽  
Medium Permeability ◽  
The Stability ◽  
The Magnetic Field ◽  
Conducting Fluids

The stability of the plane interface separating two viscous superposed conducting fluids through porous medium is studied when the whole system is immersed in a uniform horizontal magnetic field. The stability analysis is carried out for two highly viscous fluids of equal kinematic viscosities, for mathematical simplicity. It is found that the stability criterion is independent of the effects of viscosity and porosity of the medium and is dependent on the orientation and magnitude of the magnetic field. The magnetic field is found to stabilize a certain wave number range of the unstable configuration. The behaviour of growth rates with respect to viscosity, porosity and medium permeability are examined analytically.

Universality hypothesis for the small wave-number range of decaying turbulence

1995 ◽  
Vol 45 (6) ◽  
pp. 517-520
Author(s):  
L. Ts. Adzhemyan ◽  
M. Hnatich ◽  
M. Stehlik
Keyword(s):  
Wave Number ◽  
Number Range ◽  
Wave Number Range ◽  
Small Wave ◽  
Small Wave Number ◽  
Decaying Turbulence

Inviscid instability of an unbounded heterogeneous shear layer

1971 ◽  
Vol 48 (2) ◽  
pp. 405-415 ◽  
Author(s):  
S. A. Maslowe ◽  
R. E. Kelly
Keyword(s):  
Growth Rate ◽  
Froude Number ◽  
Mixing Layer ◽  
Density Variation ◽  
Wave Number ◽  
Unstable Wave ◽  
Number Range ◽  
Spatial Growth ◽  
Wave Number Range ◽  
Low Froude Number

Stability curves are computed for both spatially and temporally growing disturbances in a stratified mixing layer between two uniform streams. The low Froude number limit, in which the effects of buoyancy predominate, and the high Froude number limit, in which the effects of density variation are manifested by the inertial terms of the vorticity equation, are considered as limiting cases. For the buoyant case, although the spatial growth rates can be predicted reasonably well by suitable use of the results for temporal growth, spatially growing disturbances appear to have high group velocities near the lower cutoff wave-number. For the inertial case, it is demonstrated that density variations can be destabilizing. More precisely, when the stream with the higher velocity has the lower density, both the wave-number range of unstable disturbances and the maximum spatial growth rate are increased relative to the case of homogeneous flow. Finally, it is shown how the growth rate of the most unstable wave in the inertial case diminishes as buoyancy becomes important.

Absorption coefficient of Dupont Teflon FEP in the 20–130 wave-number range

1985 ◽  
Vol 24 (17) ◽  
pp. 2746 ◽  
Author(s):  
Mark A. Ordal ◽  
Robert J. Bell ◽  
Ralph W. Alexander ◽  
Raymond E. Paul
Keyword(s):  
Absorption Coefficient ◽  
Wave Number ◽  
Number Range ◽  
Wave Number Range

Liquid Turbulence Spectra in Two-Phase Bubbly Flow Under Turbulence Augmentation and Suppression Conditions

2006 ◽  
Author(s):  
Mohamed E. Shawkat ◽  
Chan Y. Ching ◽  
Mamdouh Shoukri
Keyword(s):  
Void Fraction ◽  
Bubbly Flow ◽  
Bubble Diameter ◽  
Optical Probe ◽  
Wave Number ◽  
Two Phase ◽  
Number Range ◽  
Turbulence Spectra ◽  
Turbulence Suppression ◽  
Wave Number Range

An experimental investigation was performed in air-water bubbly flow to study the liquid turbulence spectra in a 200mm diameter vertical pipe. A dual optical probe was used to measure the local void fraction and bubble diameter while the liquid velocities were measured using hot-film anemometry. Experiments were performed at two liquid superficial velocities of 0.2 and 0.68m/s for gas superficial velocities in the range of 0 to 0.18m/s. Generally, as the void fraction increases there is a turbulence augmentation. However, a turbulence suppression was observed near the pipe wall at the higher liquid flow rate for low void fraction. In the augmentation case, the turbulence spectra showed a significant increase in the energy at the wave number range comparable to the bubble diameter. In the suppression case, the spectra showed that suppression initially occurs at the low wave number range and then extends to higher wave numbers as suppression increased.

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