An offset-method for Euler–Lagrange approach

•Offset-method is applied to determine inter-phase values in Euler–Lagrange/DEM model.•Fluid grid is shifted in space several times and the inter-phase values are calculated.•Offset-method improves the calculation accuracy up to an order of magnitude.•Accuracy of offset-method depends highly on the resolution of the fluid grid.•Optimal ratio obtained between grid size and particle diameter in the range of 2 to 3.

An offset-method is applied to compute the inter-phase values in Euler–Lagrange approach. To investigate the influence of offset-method on the simulation accuracy and the related additional computational time, the numerical results obtained from Euler–Lagrange/Discrete Element Method are compared with measurements obtained from a lab-scale spouted fluidized bed. The results show an improvement in the calculation accuracy up to an order of magnitude. The accuracy of the procedure is depending on the fluid grid resolution, but independent of the solid loading. An optimal ratio between the grid size and the particle diameter in the range of 2–3 is suggested. The additional computational effort rises with increasing the number of particles. At same solid loading, particles with smaller diameters cause more additional computing time. In the second part of this work, the simulation results obtained from the extended Euler–Lagrange/Discrete Element Method are compared with the simulation results obtained from the Euler–Euler model and Euler–Lagrange approach combined with a stochastic collision model. Two different fluidization mass flow rates are used to investigate the capability of the simulation approaches for reproducing the hydrodynamics behaviour of the gas–solid flow in a spouted fluidized bed. The results show a good agreement with measurements regarding the fluidization regimes, the bubble size and the bed expansion. Discrepancies among the models in predicting the dynamics behaviour of the bed and the bubble formation are, however, observed. The reasons of these deviations, the advantages and limitations of the numerical techniques used are reported.

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