The problem of the motion of a spherical bubble of arbitrary size with a specified velocity in a dilute suspension of solid spherical particles is considered in the Stokes approximation for a ...carrying continuous medium. An expression is obtained for the drag of the bubble in the first approximation in the volume concentration of the dispersed phase. Using the results obtained an expression is derived for the effective viscosity of the suspension, “as seen” by the spherical bubble as it moves through the dispersed medium. It is shown that the coefficient for the volume concentration in the formula for the effective viscosity of the suspension depends on the ratio of the dimensions of the dispersed particles and of the bubble. In the limit, when this ratio approaches zero, the coefficient obtained is identical with Einstein's result for the effective viscosity of the suspension. However, this coefficient may differ considerably from Einstein's result for “non-point” dispersed particles. By comparing this result with the similar result obtained earlier for the case of the motion of a rigid sphere in a viscous suspension it is shown that the coefficient for the volume concentration in the formula for the effective viscosity of the suspension depends not only on the size of the body, but also on the form of the boundary conditions on its surface.
The motion of a cluster of an arbitrary number of spherical particles, attached to one another, in an ideal incompressible fluid is considered. Using the previously developed self-consistent field ...method, an expression is obtained for the virtual mass of the cluster in the form of an explicit function of the coordinates of all the particles. It is shown that, for special cases, the solution obtained is identical with the corresponding results known in the literature. For a statistically uniform particle distribution, using an averaging procedure over all the different possible configurations in the fluid inside a spherical volume, a simple analytic relation is obtained for the average value of the virtual mass of the spherical cluster as a function of its radius in the first approximation with respect to the volume fraction of the particles.
A new class of electrically scanned antenna arrays for the millimeter wave range is described. The antenna is based on a planar integrated ferrite travelling wave structure and is controlled by the ...magnetization of ferrite elements. Experimental antennas operating in the 8-mm wave range have the following electrical parameters: beamwidth 2 to 4/spl deg/, two dimensional scanning /spl plusmn/20/spl deg/, loss about 3 to 4 dB.< >
Measurements of direct photon production in p + Pb and p + C collisions at root(NN)-N-s = 17.4 GeV are presented. Upper limits on the direct photon yield as a function of p(T) are derived and ...compared to the results for Pb + Pb collisions at root(NN)-N-s = 17.3 GeV. The production of the eta meson, which is an important input to the direct photon signal extraction, has been determined in the eta -> 2 gamma channel for p + C collisions at root(NN)-N-s = 17.4 GeV. (c) 2012 Elsevier B.V. All rights reserved.
Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at root s(NN) = 17.4 GeV at midrapidity (2.3 less than or similar to eta(lab)less than or similar to 3.0) over the ...range 0.7 less than or similar to p(T)less than or similar to 3.5 GeV/c. The spectra are compared to pi(0) spectra measured in Pb+Pb collisions at root s(NN) = 17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N-part less than or similar to 300), the yield of pi(0)'s with p(T)greater than or similar to 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N-coll), while for central Pb+Pb collisions with N-part greater than or similar to 350, the pi(0) yield is suppressed.
The problem of the rotation of a rigid spherical body of arbitrary size in a homogeneous emulsion of gas bubbles is considered in the Stokes approximation on the basis of the self-consistent field ...method. An expression is obtained for the correction factor in Stokes’ formula for the torque acting on the body in the first approximation with respect to the volume fraction of the dispersed phase. An analytical relation is found between the factor and the sizes of the bubbles and the body. In the limit, when this ratio tends to zero, the factor obtained agrees exactly with Taylor's result for the effective viscosity of a gas bubble emulsion. It is shown that, for “non-point” bubbles, the coefficient on the volume fraction in the expression for the effective viscosity of the emulsion can considerably differ from Taylor's result.
Measurements of direct photon production in p+Pb and p+C collisions at sNN=17.4 GeV are presented. Upper limits on the direct photon yield as a function of pT are derived and compared to the results ...for Pb+Pb collisions at sNN=17.3 GeV. The production of the η meson, which is an important input to the direct photon signal extraction, has been determined in the η→2γ channel for p+C collisions at sNN=17.4 GeV.
A method for the approximate solution of the problem of many bodies of spherical form in a viscous fluid is developed in the Stokes approximation. Using a purely hydrodynamic approach, based on the ...use of the concept of a self-consistent field, the classical boundary value problem is reduced to a formal procedure for solving a linear system of algebraic equations in the tensor coefficients, which occur in the solution obtained for the velocity field and pressure of the liquid. A procedure for the approximate solution of this system of equations is constructed for the case of dilute suspensions, when the ratio of the size of the dispersed particles to the characteristic distance between them is a small parameter. Finally, the initial boundary value problem is reduced to solving a recurrent system of equations, in which each subsequent approximation for all the required quantities depends solely on the previous approximations. The system of recurrent equations obtained can be solved analytically in any specified approximation with respect to a small parameter. It is shown that this system of equations contains in itself all possible physical formulations of the problems, and, within the frameworks of the mathematical procedure constructed, they are distinguished solely by a set of specified and required functions. The practical possibilities of the method are in no way limited by the number of dispersed particles in the fluid.
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