Modelo matemático para análise dos efeitos da turbulência em escoamentos bifásicos fluido - partícula / Mathematical model for turbulence effect analysis in two-phase flow type fluid-particle

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

In this work the effect of particles or drops, which constitute the dispersed phase, is analyzed in the turbulence of the continuous phase (gas or liquid). This type of analysis, which is known as turbulence modulation, searchs to get the variations in the terms sources of generation of kinetic energy provoked by the interaction of particles with the continuum flow. In this development, one uses three types of applied distinct mathematical tools to the analysis of the mechanic of fluid: statistics of the turbulence, particle aerodynamics and the computational fluid dynamics (CFD). The statistics of the turbulence it is used to describe the turbulent flow by concentration or distribution of vortices. From the assintotical analysis an expression for the function of speeds distribution of the vortices meets, which is compared with the experimental results of Castaing et al. (1990). With the study of the interaction effect vortex-particle, together with the inclusion of the terms of generation of vortices in the particle backflow, an expression meets an equation of variation of the kinetic energy of the turbulence which is validated with the experimental results compiled by of Crowe (2000). Searching to insert the transient effect provoked by vortices of similar dimensions to the particle diameter of the dispersed phase, one meets from numerical results, an analytical expression for the coefficient of spherical particle drag with behavior modified by vortices. These numerical results are validated with those gotten by Kim et al. (1985). Finally, an expression for the variation of the kinetic energy of the turbulence is gotten that get all the considered effect above.

ASSUNTO(S)

interação particulas interação vórtice-esfera modulação da turbulência fluid-particle flow força de arrasto turbulência velocity fluctuation escoamento bifásico intermitência de pequenas escalas small-scale intermittency turbulence modulation two-phase flow trhee-dimensional finite volume escoamento de fluido-particula particles-turbulence interaction volume finito tridimensional drag force flutuação da velocidade sphere-vortex interaction

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