BRIEFS OSCILLATORY BEHAVIOR OF NORMAL STRESSES IN VISCOELASTIC FLUIDS
This paper deals with the time-dependent behavior of normal stresses exhibited by fluids in small-amplitude oscillation. The equations of motion for a cone-and-plate system are solved to relate the amplitude and phase relationships of the oscillating stresses to experimental measurements. The results are expressed in terms of a “complex normal stress coefficient” and a “normal stress displacement function.” Finally, the predictions of several phenomenological models (Oldroyd, and Coleman and Noll) are compared to suggest ways in which data may ultimately be analyzed. A three-constant Oldroyd model is particularly helpful in estimating orders of magnitude of various effects. A new relation has been found between the normal stress displacement function and the imaginary part of the complex viscosity. Michael C. Walliams and R. Byron Bard, Chemical Engineering Department, University of Wisconsin, Madzson, W i s . IND.END.CHEM.FUNDAMENTALS 3,42-49 (1964) EDDY FORMATION I N FILM FLOW DOWN A VERTICAL PLATE
By an adaptation of Kapitza’s theory of wave formation, the generation of circulating eddies in a falling film of liquid on vertical planes is explained. Regions of reversed flow can exist under the troughs of a periodic traveling wave. It is claimed that this feature indicates the existence of the appropriate conditions for the formation of circulating eddies in the wavy flow. Stanislaw Portalski, Battersea College of Technology, London, S. W. 7 1, England IND.ENC.CHEM.FUNDAMENTALS 3 , 49-53 (1964) INITIAL INSTABILITY OF A VISCOUS FLUID INTERFACE
Initial instability of the interface between two viscous fluids, one being moved impulsively past the other at a constant velocity, is investigated theoretically by an analysis of the growth of small disturbances and experimentally by microsecond photomicrographs of a liquid jet injected into another liquid. For various limiting cases theory is developed relating Weber number based on the wavelength of the fastest growing disturbance to a dimensionless viscosity number, viscosity ratio, and density ratio. This theory is then used with experimental data to construct an empirical correlation valid for a general planar system. This correlation can be shown to be valid also for liquid jets of sufficient diameter and viscosity. W. E. Rana and W. M . Dreaer, Jr., Department of Chemzcal Enganeering, Universaty of Minnesota, Minneapolis 14, Minn. IND.ENC.CHEM.FUNDAMENTALS 3, 53-60 (1964) RADIAL GAS MIXING IN FLUIDIZED-PACKED BEDS
A study of radial gas mixing in various systems composed of particles fluidized in the voids of fixed packing was made in support of process development work associated with the reprocessing of spent nuclear fuels. Gas mixing was studied in systems involving various combinations of packing (l/~-,l / 4 - , and l/s-inch spheres and X 3/s-inch cylinders) and fluidizing materials (0.0080- and 0.0110-inch glass beads, -54 +lo0 mesh alundum, and -100 4-140 mesh copper). Values of gas eddy diffusivities in the fluidized-packed beds were nearly the same as values in beds with the same type of packing but without the fluidized material. However, because of the nonuniform pressure gradients associated with fluidization there were larger variances in the eddy diffusion coefficients for the fluidized-packed bed case. John D. Gabor and Walliam J. Mecham, Argonne National Laboratory, Argonne, Ill. IND.ENG.CHEM.FUNDAMENTALS 3 , 60-65 (1964) CONVEYABILITY OF MATERIALS OF MIXED PARTICLE
SIZE
The minimum velocities required to convey single particles in horizontal flow are correlated with Reynolds number in terms of the conventional drag coefficient. Experimental data obtained in l’jr-inch and 21/*-inch pipe agree with measurements of sand movements in the open desert. The results have practical significance in establishing the lowest limit of velocity in pneumatic conveying without saltation. The minimum velocities necessary for saltation-free conveying of mixed size materials under various degrees of solids loading are correlated with the single-particle saltation velocity of the most difficultly transported size in the
mixture. A parameter in this correlation is a constant characterizing the size and spread of sizes of the particles in the mixture. This constant is calculable from the particle size analysis and, in combination with the saltation velocity correlation, can be used as a criterion for distinguishing between materials more feasibly transported in dilute or in dense phase.
Frederick A. Zenz, T h e Polytechnic Institute of Brooklyn, Brooklyn, N . Y. IND.ENG.CHEM.FUNDAMENTALS 3, 65-75 (1964) EFFECT OF ELECTRIFICATION O N THE DYNAMICS OF A PARTICULATE SYSTEM
The significance of electrification on the dynamics of a gas-solid system was studied. At low temperatures, electrification of solid particles occurs because of impact with a wall. Basic considerations include motion of charged particles with spherical symmetry and axi-symmetry. It is shown that the pinch effect due to motion of particles charged to the same sign is insignificant. However, even a very slight charge on the solid particles will have a pronounced effect on concentration distribution in the flow of a gassolid system.
S. I,. Soo, U n i v m i t y of Illinois, Urbana, 1Ll. IND.END.CHEM.FUNDAMENTALS 3 , 75-80 (1964) ULTRAPURIFICATION BY DISTILLATION
With the recent progress in the science of the solid state, it has become increasingly essential to use materials of exceedingly high purity. Fractional distillation shows great promise as an effective technique for preparing ultrapure materials. The special equations necessary to design such a batch distillation are derived. They are much simpler than the usual batch distillation equations, because the quantity of the second component is very small in ultrapurification. W. A. Wilcox, Pacijc Semiconductors, Inc., Lawndale, Calif. IND.ENC.CHEM.FUNDAMENTALS 3, 81-83 (1964) TOTAL FLOW RATES I N AN ISOTOPE SEPARATION SYSTEM
The cascade for isotope separation, working with constant cut numbers and a given number of stages for a desired enrichment, is treated. This paper presents a simple general calculation of a material cascade balance in any intermediate stage, for the above conditions. The choice of cut numbers is discussed.
Alexander Apelblat and Gideon Pery, Israel Atomic Energy Commission, Tel-Aviv, Israel IND.ENC. CHEM.FUNDAMENTALS 3 , 83-85 (1964) COMMUNICATION. REACTION
PHASE EQUILIBRIA A N 3 THE TELOMERIZATION
Two-component gas-liquid mixtures encountered in organic reactions performed at elevated pressures frequently deviate seriously from ideal solubility behavior. Three-phase systems of compositions very sensitive to pressure and temperature changes may be produced. This phenomenon is exemplified with the system ethylene-ethyl bromoacetate reactants applied to a telomerization reaction study, and its influence on the product composition is discussed.
L. M . Shorr, Manjred Rogozinski, Andre Varsanvi, and AvTaham Banicl, Israel Mining Industries Laboratories, Haifa, Israel IND.ENG.CHEM.FUNDAMENTALS 3, 86-87 (1964) COMMUNICATION. VISCOMETER
NON-NEWTONIAN FLOW I N A ROLLING BALL-
A straightforward extension of the Lewis theory for Newtonian fluids which might be applied to other non-Newtonian models.
R. Byron Bird and R a 8 M . Turian, Department of Chemical Engineering, University of Wisconsin, Madison, Wis. IND.END.CHEM.FUNDAMENTALS 3, 87 (1964) CORRESPONDENCE
Comments on an article by M. R. Hoare [Ind. Eng. Chem. 53, 197 (1961)] on determining true residence times in flow-system reactions. J . C. R. Turner, University of Cambridge, Cambridge, England IND.END.CHEM.FUNDAMENTALS 3 , 8 8 (1964) VOt. 5 6
NO. 2
FEBRUARY 1 9 6 4
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