Numerical simulation of fluid flow in CFB risers - A turbulence analysis approach

Abstract

Turbulence parameters are derived from results of numerical simulation of gas-solid flow in circulating fluidized bed (CFB). A two fluid model with constant viscosity is applied considering an Eulerian continuum approach for both phases. An analysis is performed using a direct numerical integration of balance equations without an explicit use of any turbulence model for both phases. Even though velocity fluctuations of lower scales are eliminated by the considered computational mesh, fluctuations of larger scales are detected and analyzed. The results show that the Reynolds stresses behave according to the expected for a turbulent flow, and a reasonable agreement is found regarding literature experiment. Following the literature, granular temperature is derived from the Reynolds stresses, and qualitatively matches the expected behavior as described by the kinetic theory of granular flow. Finally, it is seen that solid's phase turbulence is captured using the present approach. Copyright © 2005 by ABCM.