Formation and Separation of Thin Viscous Film in Hertzian Line Contacts

1980 ◽  
Vol 102 (4) ◽  
pp. 466-477 ◽  
Author(s):  
Ge´rard Dalmaz
Keyword(s):  
Thin Film ◽  
Stability Criterion ◽  
Reverse Flow ◽  
Film Formation ◽  
Hertzian Contact ◽  
Wave Number ◽  
Line Contacts ◽  
The Stability ◽  
Film Separation ◽  
Maximum Amplification

The conditions of film formation and of film separation are examined experimentally and theoretically in a line Hertzian contact when the inlet region is partially filled with oil, in steady state hydrodynamic regime, for both rolling and sliding conditions. It is shown experimentally that the importance of the parameter μU/T (viscosity and speed/surface tension) differs at inlet and exit. At contact exit the influence of μU/T is dominant and the film divides to form a meniscus which can be stable or unstable. The validity of the Coyne and Elrod model is confirmed. At contact inlet when reverse flow disappears, a meniscus is also formed with a downstream circulation zone. The instability of the exit air-oil meniscus is studied theoretically using the linearized perturbation method with the thin film assumptions. A simple and complete analytical solution yields both a stability criterion and the wave number for the linear contact geometry. These results which are compared with experiments for thin film and for 0.01 < μU/T < 1 show the validity of the stability criterion and that best agreement is obtained with the wave number of maximum amplification.

The Meniscus Instability of a Thin Liquid Film

1988 ◽  
Vol 55 (4) ◽  
pp. 975-980 ◽  
Author(s):  
H. Koguchi ◽  
M. Okada ◽  
K. Tamura
Keyword(s):  
Thin Film ◽  
Analytical Solution ◽  
Liquid Film ◽  
Tilt Angle ◽  
Stability Criterion ◽  
Thin Liquid Film ◽  
Normal Direction ◽  
Wave Number ◽  
The Stability ◽  
Maximum Amplification

This paper reports on the instability for the meniscus of a thin film of a very viscous liquid between two tilted plates, which are separated at a constant speed with a tilt angle in the normal direction of the plates. The disturbances on the meniscus moving with movement of the plates are examined experimentally and theoretically. The disturbances are started when the velocity of movement of the plates exceeds a critical one. The wavelength of the disturbances is measured by using a VTR. The instability of the meniscus is studied theoretically using the linearized perturbation method. A simple and complete analytical solution yields both a stability criterion and the wave number for a linear thickness geometry. These results compared with experiments for the instability show the validity of the stability criterion and the best agreement is obtained with the wave number of maximum amplification.

Intrinsic Thermal Stability of Anisotropic Thin-Film Superconductors

1990 ◽  
Vol 112 (1) ◽  
pp. 10-15 ◽  
Author(s):  
M. I. Flik ◽  
C. L. Tien
Keyword(s):  
Thin Film ◽  
Thermal Stability ◽  
Stability Criterion ◽  
High Temperature Superconductors ◽  
Stability Criteria ◽  
Anisotropic Thermal Conductivity ◽  
Operating Current ◽  
Released Energy ◽  
The Stability ◽  
Thermal Stability Of

Intrinsic thermal stability denotes a situation where a superconductor can carry the operating current without resistance at all times after the occurrence of a localized release of thermal energy. This novel stability criterion is different from the cryogenic stability criteria for magnets and has particular relevance to thin-film superconductors. Crystals of ceramic high-temperature superconductors are likely to exhibit anisotropic thermal conductivity. The resultant anisotropy of highly oriented films of superconductors greatly influences their thermal stability. This work presents an analysis for the maximum operating current density that ensures intrinsic stability. The stability criterion depends on the amount of released energy, the Biot number, the aspect ratio, and the ratio of the thermal conductivities in the plane of the film and normal to it.

Influence of viscosity temperature dependence on the spectral characteristics of the thermoviscous liquids flow stability equation

2019 ◽  
Vol 14 (1) ◽  
pp. 52-58 ◽  
Author(s):  
A.D. Nizamova ◽  
V.N. Kireev ◽  
S.F. Urmancheev
Keyword(s):  
Reynolds Number ◽  
Spectral Characteristics ◽  
Wave Number ◽  
Critical Parameters ◽  
Fluid Viscosity ◽  
Flat Channel ◽  
Stability Equation ◽  
The Stability ◽  
Thermoviscous Fluid ◽  
Sommerfeld Equation

The flow of a viscous model fluid in a flat channel with a non-uniform temperature field is considered. The problem of the stability of a thermoviscous fluid is solved on the basis of the derived generalized Orr-Sommerfeld equation by the spectral decomposition method in Chebyshev polynomials. The effect of taking into account the linear and exponential dependences of the fluid viscosity on temperature on the spectral characteristics of the hydrodynamic stability equation for an incompressible fluid in a flat channel with given different wall temperatures is investigated. Analytically obtained profiles of the flow rate of a thermovisible fluid. The spectral pictures of the eigenvalues of the generalized Orr-Sommerfeld equation are constructed. It is shown that the structure of the spectra largely depends on the properties of the liquid, which are determined by the viscosity functional dependence index. It has been established that for small values of the thermoviscosity parameter the spectrum compares the spectrum for isothermal fluid flow, however, as it increases, the number of eigenvalues and their density increase, that is, there are more points at which the problem has a nontrivial solution. The stability of the flow of a thermoviscous fluid depends on the presence of an eigenvalue with a positive imaginary part among the entire set of eigenvalues found with fixed Reynolds number and wavenumber parameters. It is shown that with a fixed Reynolds number and a wave number with an increase in the thermoviscosity parameter, the flow becomes unstable. The spectral characteristics determine the structure of the eigenfunctions and the critical parameters of the flow of a thermally viscous fluid. The eigenfunctions constructed in the subsequent works show the behavior of transverse-velocity perturbations, their possible growth or decay over time.

scholarly journals Causality and stability conditions of a conformal charged fluid

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Farid Taghinavaz
Keyword(s):  
Chemical Potential ◽  
Second Law Of Thermodynamics ◽  
Dense Medium ◽  
Wave Number ◽  
Second Law ◽  
Stability Conditions ◽  
Charged Fluid ◽  
Large Wave ◽  
The Stability ◽  
Large Wave Number

Abstract In this paper, I study the conditions imposed on a normal charged fluid so that the causality and stability criteria hold for this fluid. I adopt the newly developed General Frame (GF) notion in the relativistic hydrodynamics framework which states that hydrodynamic frames have to be fixed after applying the stability and causality conditions. To do this, I take a charged conformal matter in the flat and 3 + 1 dimension to analyze better these conditions. The causality condition is applied by looking to the asymptotic velocity of sound hydro modes at the large wave number limit and stability conditions are imposed by looking to the imaginary parts of hydro modes as well as the Routh-Hurwitz criteria. By fixing some of the transports, the suitable spaces for other ones are derived. I observe that in a dense medium having a finite U(1) charge with chemical potential μ0, negative values for transports appear and the second law of thermodynamics has not ruled out the existence of such values. Sign of scalar transports are not limited by any constraints and just a combination of vector transports is limited by the second law of thermodynamic. Also numerically it is proved that the most favorable region for transports $$ {\tilde{\upgamma}}_{1,2}, $$ γ ˜ 1 , 2 , coefficients of the dissipative terms of the current, is of negative values.

scholarly journals Growth of Gaseous Macromolecules in the Downstream Region of Perfluorocompounds Plasmas-Observation, Reaction Mechanism, Thin Film Formation-

Shinku ◽  
2006 ◽  
Vol 49 (3) ◽  
pp. 195-197
Author(s):  
Kenji FURUYA ◽  
Shinobu YUKITA ◽  
Hiroshi OKUMURA ◽  
Ryoichi NAKANISHI ◽  
Makoto MAKITA ◽  
...  
Keyword(s):  
Thin Film ◽  
Reaction Mechanism ◽  
Film Formation ◽  
Downstream Region ◽  
Thin Film Formation

A facile room temperature chemical transformation approach for binder-free thin film formation of Ag2Te and lithiation/delithiation chemistry of the film

2016 ◽  
Vol 45 (43) ◽  
pp. 17312-17318 ◽  
Author(s):  
Eun-Kyung Kim ◽  
Dasom Park ◽  
Nabeen K. Shrestha ◽  
Jinho Chang ◽  
Cheol-Woo Yi ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Aqueous Solution ◽  
Ion Exchange ◽  
Chemical Transformation ◽  
Room Temperature ◽  
Film Formation ◽  
Synthetic Method ◽  
Binder Free ◽  
Thin Film Formation

An aqueous solution based synthetic method for binder-free Ag2Te thin films using ion exchange induced chemical transformation of Ag/AgxO thin films.

Giant magnetostrictive thin film formation by plasma process

2003 ◽  
Vol 169-170 ◽  
pp. 613-615 ◽  
Author(s):  
T. Yamaki ◽  
M. Sekine ◽  
T. Haraki ◽  
H. Uchida ◽  
Y. Matsumura
Keyword(s):  
Thin Film ◽  
Film Formation ◽  
Plasma Process ◽  
Thin Film Formation

The flow of a micropolar liquid layer down an inclined plane

1968 ◽  
Vol 64 (2) ◽  
pp. 513-526 ◽  
Author(s):  
A. J. Willson
Keyword(s):  
Thin Films ◽  
Steady State ◽  
Liquid Layer ◽  
Stability Criterion ◽  
Long Waves ◽  
Inclined Plane ◽  
The Stability ◽  
Micropolar Liquid

AbstractConsideration is given to the flow of a micropolar liquid down an inclined plane. The steady state is analysed and Yih's technique is employed in an investigation of the stability of this flow with respect to long waves. Detailed calculations are given for thin films and it is shown that the micropolar properties of the liquid play an important role in the stability criterion.

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