Showing papers in "International Journal of Multiphase Flow in 1994"

TL;DR: In this article, it was shown that for a wide varicty of both fixed-bed and suspended-particle systems, file voidage function may be expressed as ϵ−β, where the exponent β is dependent on the particle Reynolds number but independent of other system variables.

TL;DR: Preferential concentration describes the accumulation of dense particles within specific regions of the instantaneous turbulence field as mentioned in this paper, which occurs in dilute particle-laden flows with particle time constants of the same order as an appropriately chosen turbulence time scale.

TL;DR: In this paper, the lateral phase distribution in bubbly flows in vertical ducts was analyzed using a three-dimensional two-fluid model based on analytic and experimental information on the behavior of a single bubble, and on the assumption of linear superposition of shear-induced and bubble-induced turbulence.

TL;DR: A survey of fundamental studies on the critical heat flux (CHF) phenomenon can be found in this paper, where the materials have been classified into four main boiling modes, subdivided into individual important topics and arranged in a proper sequence so as to show the synthetic framework of the CHF phenomenon.

TL;DR: Similitude is a powerful tool which allows a small laboratory experiment at ambient conditions to simulate a much larger commercial fluidized bed as mentioned in this paper, and the scaling laws for bed dynamics and heat transfer are systematically developed from the fundamental relationships.

TL;DR: In this paper, a near-forward light scatter detection method was proposed to estimate the particle size and velocity in the presence of a dispersed phase in a two-phase turbulent flow.

TL;DR: In this paper, infrared thermography was used to study the thermal interaction between the particle-laden turbulent flow and a heated plate, and the maximum amplitude of wall temperature fluctuations reached ±40% of the difference between the average wall temperature and the fluid bulk temperature.

TL;DR: In this article, the effects of the interparticle distance and particle Reynolds numbers on the drag forces of both the trailing and leading particles are examined, and an empirical equation is obtained to describe the drag force variation of a single particle trailing in the wake of a leading particle.

TL;DR: The early use of immersed probes of various kinds is assessed critically and compared with more recently developed non-invasive techniques, such as tomographic imaging as discussed by the authors, and the complete velocity spectrum from bubbling through turbulent to fast operation is considered and main conclusions obtained regarding gas and particle dynamics are presented.

TL;DR: In this paper, a simplified theory for the particles-turbulence interaction in a dilute two-phase flow with particles of arbitrary sizes is proposed, which takes into account two sources of turbulence in particle-laden flows: (i) the carrier fluid velocity gradients; and (ii) turbulent wakes behind the coarse particles.

TL;DR: In this article, a numerical study of the drainage and rupture of the liquid film between two drops whose centres approach each other at constant velocity is presented, restricted to the partially-mobile case and to small approach velocities.

TL;DR: In this paper, the history term (often referred to as the Basset term) was added to the equation of motion of a sphere to make it explicit in the velocity and acceleration.

TL;DR: In this article, the authors provide a general review of two-phase critical flow from the viewpoint of the needs of thermal-hydraulic systems codes and conduct a systematic evaluation of the existing data and theoretical models in order to quantify the validity, under various conditions, of several of the more widely used critical flow models.

TL;DR: In this article, the authors investigated viscous resuspension of heavy particles in fully developed laminar flows in a horizontal pipe by extending the model used previously for unidirectional flows to cases in which all three velocity components are non-zero due to the existence of a secondary motion within the cross section of the pipe.

TL;DR: In this article, the stability of separated flows is discussed using two approaches: the interfacial stability analysis and the structural stability analysis, using linear and non-linear analyses, respectively.

TL;DR: In this paper, the vertical two-phase crossflow on the shell side of a horizontal tube bundle was studied and flow patterns were established and visual observation together with photographic data and a video-film were used.

TL;DR: In this paper, the phase distribution and turbulence structure for solid/fluid upflow in a vertical pipe were investigated using a laser-Doppler anemometer (LDA).

TL;DR: In this paper, the authors measured the lateral variation of the liquid properties by making measurements at locations Θ = 0° (pipe bottom) and Ω = 45° and found that a small film thickness is associated with reduced local shear stress.

TL;DR: In this paper, a slug-tracking model is proposed that follows the behavior of all individual slugs and is capable of simulating the aforementioned processes in a hilly terrain pipeline, where slugs can be generated at low elbows, dissipate at top elbows and shrink or grow in length as they travel along the pipe.

TL;DR: A review of the use of numerical simulations to study the motion of particles in turbulent flows can be found in this article, where the main emphasis is on direct numerical simulation (DNS).

TL;DR: In this article, the authors studied the shear-induced inertial migration of a rigid sphere in a fluid undergoing a uniform shear between two parallel walls and compared the experimentally measured migration velocities with those predicted by the asymptotic formulas previously given by Saffman and McLaughlin.

TL;DR: In this article, an experimental study of the effect of temperature (up to 910°C) on the fluidization characteristics of three powders, chosen to span the fine-to-moderate size range, is presented.

TL;DR: In this paper, a Monte Carlo simulation for particles in a low Reynolds number, isotropic, Gaussian, pseudo turbulence is used to investigate the effect of trajectory bias on the settling velocity.

TL;DR: In this article, the phase distribution and junction pressure drops of low-pressure air-water mixtures at a horizontal, equal-sided (37.6 mm i.d.) dividing tee junction were investigated.

TL;DR: In this article, a model of core-annular flow in which the oil core is a perfect cylinder with generators parallel to the pipe wall, but off-center, is studied in laminar and turbulent flow to assess the effects of eccentricity and the volume flow rate ratio on the friction factor and holdup ratio.

TL;DR: In this article, the influence of a second immiscible liquid on gas-liquid slug flow has been investigated, and well-known models for the prediction of the slug frequency and pressure loss, as well as the flow pattern maps of two-phase flow, were extended for this special kind of multiphase flow.

TL;DR: In this article, a phenomenological void growth model is presented which accounts for the vapor volume inside a heated channel at atmospheric pressure, and includes the bubble ebullition cycle, formulated on the basis of information obtained from a high speed photographic study.

TL;DR: In this paper, the effect of particle size and concentration on the intensity of turbulent fluctuations in two-phase flows was analyzed based on Prandtl's mixing-length theory, modified to account for the viscous interaction of small particles and carrier fluid as well as an effect of the admixture inertia.

TL;DR: In this article, the authors derived the droplet size distribution function for sprays using the maximum entropy formalism (MEF) to link the end stage of the atomization process to an intermediate state, characterized by unstable liquid cylinders.

TL;DR: In this paper, a numerical model for the simulation of the interaction of weak shock waves with open-cell compressible porous foams is developed, where the foam is assumed to be infinitely weak and that its volume fraction is relevant only when the interaction between the gaseous and the solid phases is considered.