Showing papers on "Slip ratio published in 1968"

Affected Volume and Temperature Rise During Discontinuous Slip at Low Temperatures

Abstract: The temperature transients arising from discontinuous slip in copper‐nickel alloys at helium temperature have been observed with thermometers of defined inertia properties. It is found that this type of slip can propagate through the specimen similar to a Luders band. In the discussed case, the temperature rises from approximately 5°K to approximately 35°K, and the mean value of the volume affected by each slip is 1.4×10−3 cm3. This volume corresponds very closely to the range of thermal diffusion during the time interval of slip. Thus, it is consistent with the assumption that discontinuous slip at low temperatures results from thermal feedback.

Laminar Boundary Layer with Mass Transfer and Slip

Abstract: A method is developed to solve the two‐dimensional incompressible laminar boundary layer with mass transfer and slip at the surface. The properties of the injected gas are assumed the same as those of the main flow. The velocity distribution is nonsimilar in the flow direction and is obtained by a series expansion in terms of a mass transfer parameter e(S) and a slip parameter σ(S). Results are presented for various combinations of the two parameters. The validity of the method is verified by comparison with a momentum integral type solution over a range of values of the two parameters.

A Theoretical Approach to Two-Phase Critical Flow : (3rd Report, The Critical Condition Including Interphasic Slip)

Abstract: "Eigenvalue method", already proposed by the author for two-phase critical flow, is developed for the axial steady flow equations system where separate momentum conservation can be strictly postulated. Besides the comparisons of physical meanings in two-phase critical flow between energy and entropy, conservation equations are also investigated. The conclusions for steam water mixtures are as follows. (1) "Eigenvalue method"defines the criticality as the discontinuous condition of steady flow differential equations system and can treat easily such a complicated system composed of separate momentum between two phases, energy, and mass conservation equations. (2) The solutions given by the above theory can well explain the former empirical data except for critical slip ratio which has not well been investigated experimentally. (3) Critical condition with energy conservation gives a more accurate solution than one with entropy conservation. But the latter is still good approximation.

Effect of incomplete accommodation on the slip coefficient.

Abstract: : The sensitivity of the value of the slip coefficient obtained from different models of the wall boundary condition was determined by a kinetic theory analysis of the problem of uniform shear flow (Kramer's problem). Solutions were obtained for two models of the wall boundary condition. The first model is that of Maxwell, in which it is assumed that a fixed fraction of the incident particles reflects diffusely and the remainder reflects specularly. The second model is a special case of a more general model previously developed by the author to account for the fact that the nature of the reflection process depends on the velocity of the impinging particle. These solutions were used for determination of the variation of the slip coefficient with the gas-surface interaction parameters. At a fixed value of the tangential momentum accommodation coefficient, the two models may yield significantly different values of the slip coefficient. It is found that the slip coefficient corresponding to the new model is always greater than or equal to the value corresponding to Maxwell's model. The two values differ by a factor of as much as 8/pi at small values of the accommodation coefficients. (Author)