On the Performance of Different Rans Based Models to Describe the Turbulent Flow in an Agitated Vessel Using Non-Structured Grids and Piv Validation

Abstract

The performances of the Standard κ-ε, RNG, Realizable, κ-w and RSM turbulence models to describe the behavior of the flow in agitated tank reactors were evaluated. Because most of these tanks have complex geometries, structured meshing schemes are not a practical alternative in engineering. Two particular unstructured meshing schemes composed of either Cartesian Cut-Cell (CC) or Tetrahedral elements were tested in domains larger than 3 million cells. In this work, the blade thickness, which is usually disregarded, was accounted for. The performance of the turbulence models was validated by PIV measurements. A strong dependence on the grid size and the power number was found, with CC grids having good agreement with grids > 3.6 Million. The pumping number was independent of the cell number and the values agree with experimental data. The Realizable model resolved with a tetrahedral grid presented the overall best performance.

Análisis de patrones turbulentos de un tanque agitado, utilizando dinámica de fluidos computacional y velocimetría por imágenes de partículas

“…Antes de iniciar la simulación LES y con el objetivo de lograr una convergencia de los resultados en un menor tiempo, se recomienda utilizar una solución inicial mediante una simulación RANS empleando un modelo de dos ecuaciones como mínimo [124]. En este caso se utilizó el modelo de turbulencia κ-ε realizable, debido a los buenos resultados obtenidos con anterioridad [125].…”