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Grid convergence study of a cyclone separator using different mesh structures

Oliveira R.A.F. (Federal University of São Carlos, Department of Chemical Engineering, São Carlos, São Paulo, Brazil)
Justi G.H. (Federal University of Mato Grosso, Institute of Engineering, Cuiabá, Mato Grosso, Brazil)
Lopes G.C. (Federal University of São Carlos, Department of Chemical Engineering, São Carlos, São Paulo, Brazil)

In a cyclone design, pressure drop and collection efficiency are two important performance parameters to estimate its implementation viability. The optimum design provides higher efficiencies and lower pressure drops. In this paper, a grid independence study was performed to determine the most appropriate mesh to simulate the two-phase flow in a Stairmand cyclone. Computational fluid dynamic (CFD) tools were used to simulate the flow in an Eulerian-Lagrangian approach. Two different mesh structure, one with wall-refinement and the other with regular elements, and several mesh sizes were tested. The grid convergence index (GCI) method was applied to evaluate the result independence. The CFD model results were compared with empirical correlations from bibliography, showing good agreement. The wall-refined mesh with 287 thousand elements obtained errors of 9.8% for collection efficiency and 14.2% for pressure drop, while the same mesh, with regular elements, obtained errors of 8.7% for collection efficiency and 0.01% for pressure drop.

Keywords: CFD, cyclone separator, bagasse soot, numerical mesh, Grid Convergence Index