Large eddy simulations of a stirred tank using the lattice Boltzmann method on a nonuniform grid

A nonuniform grid lattice Boltzmann technique previously described by He et al. [I] has been extended to simulate three-dimensional flows in complex geometries. The technique is applied to the computation of the turbulent flow in a stirred tank driven by a standard Rushton turbine. With the nonuniform grid approach, the total CPU time required for a simulation of the flow in a stirred tank can be reduced by roughly 75% and still provide the same spatial accuracy as would be obtained with a uniform high-resolution grid. Statistical results for the computed flow fields will be compared with experimental results (H. Wu and G. K, Patterson, Chem, Eng. Sci. 44, 2207 (1989)) and with simulations by J. G, M. Eggels (Int. J. Heat Fluid Flow 17, 307 (1996)) and J. J. Derksen and H. E. A. Van den Akker (AIChE J. 45. 209 (1999)). The results of the nonuniform mesh simulation are in reasonable agreement with the available experimental data and the results of previous simulations. (C) 2002 Elsevier Science (USA).