Dynamic multiscale method for gas‐solid flow via spatiotemporal coupling of two‐fluid model and discrete particle model

Abstract

Various computational fluid dynamics methods have been developed to study the hydrodynamics of gas‐solid flows, however, none of those methods is suitable for all the problems encountered due to the inherent multiscale characteristics of gas‐solid flows. Both discrete particle model (DPM) and two‐fluid model (TFM) have been widely used to study gas‐solid flows, DPM is accurate but computationally expensive, whereas TFM is computationally efficient but its deficiency is the lack of reliable constitutive relationships in many situations. Here, we propose a hybrid multiscale method (HMM) or dynamic multiscale method to make full use of the advantages of both DPM and TFM, which is an extension of our previous publication from rapid granular flow (Chen et al., Powder Technol. 2016;304:177–185) to gas‐solid two‐phase flow. TFM is used in the regions where it is valid and DPM is used in the regions where continuum description fails, they are coupled via dynamical exchange of parameters in the overlap regions. Simulations of gas‐solid channel flow and fluidized bed demonstrate the feasibility of the proposed HMM. The Knudsen number distributions are also reported and analyzed to explain the differences. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3681–3691, 2017

Unified gas-kinetic wave-particle method for gas-particle two phase flow from dilute to dense solid-particle limit

“…For the EE approach, it will difficult to give an accurate prediction when Kn number of particle phase is large, because EE approach cannot capture non-equilibrium physics of solid particles, such as particle trajectory crossing (PTC) phenomenon [2,34]. Based on the features of EE and EL approach, many studies focus on the hybrid method, coupling Eulerian and Lagrangian approach together for solid particle phase, to maintain both the accuracy and computation efficiency [40,6,64,38]. In the hybrid method, it is a challenge to define an accurate and reliable criterion for the smooth transition between the Eulerian and Lagrangian approaches for disperse phase.…”