Closures for Meso-scale Models of Dense Suspensions - The Euler-Lagrange Perspective

Abstract

The mechanistic modeling of flow phenomena in various processes of the chemical industry is a formidable challenge, especially in case dense fluid-particle suspensions are involved. In addition, transport of species and thermal energy needs to be considered to make reliable predictions, e.g., on the performance of a chemical reactor. In certain situations, even the transport of a third phase, e.g., liquid droplets in a gas-particle flow, needs to be considered for a mechanistically-correct description of the flow.
This talk first summarizes challenges associated with the development of Euler-Lagrange (EL) models to describe the transport of momentum, heat, and mass. The focus is on gas-particle suspensions which are encountered in the energy and pharmaceutical industry. Second, test cases are presented that highlight weaknesses in (i) traditional numerical schemes, e.g., to reconstruct the voidage at the particle location, as well as (ii) closure models. Third, strategies to development new closures for EL models are reviewed. Thereby the focus is on closures for momentum and heat transfer that are used in simulations of meso-scale phenomena. The fourth and final section provides a perspective on the most promising strategies to improve the reliability and validity of EL models. This perspective is illustrated by results of ongoing research activities that aim on using an advanced set of closures. Unlike most other formulations, this advanced set of closures is developed specifically for EL models, i.e., it aims on predicting per-particle transfer coefficients.