(7d) Intermediate Regime in Particle-Fluid Flow

Simulations of the multi-phase flow in fluidised beds are presented. Some of the results rely on a model describing the solid stresses in particle laden flow. The model is shown to be valid for slow and intermediate flows and is developed following the theory developed by Tardos et al. (2003). The study extends previous work by Makkawi et al. (2006), where a steady one-dimensional particle flow model was used to demonstrate the smooth merge of quasi-static flow with “liquid-like” behaviour. The work aims at studying the solid stress in conjunction with a number of numerical codes. Validation is then undertaken using electrical capacitance tomography (ECT) measurements.

The time series data of solid fraction fluctuation, averaged within 14.5-18.5 cm above the distributor level, at 3 different fluidisation velocities are studied. In addition, comparisons are undertaken using different simulation software, namely OpenFOAM, Fluent and MFix.

The comparisons undertaken are used to detect which modelling framework and which software are more suitable to represent the behaviour of particle laden flow. The merge between flow regimes and the characteristics of the intermediate regime bring to the conclusion that a more complex constitutive law for the solid stresses is needed.

References

[1] G.I. Tardos, S. McNamara, I. Talu, Powder Technology. 2003;131(1):23-39.

[2] Y.T. Makkawi, P.C. Wright, R. Ocone, Powder Technology. 2006;163(1):69-79.