Simulating particle-laden flows: From immersed boundaries towards model order reduction

Abstract

Particle-laden flow is prevalent both in nature and in industry. Its appearance ranges from the transport of riverbed sediments towards the magma flow; from the deposition of catalytic material inside particulate matter filters in automotive exhaust gas aftertreatment towards the slurry transport in dredging operations. In this contribution, we focus on the particle-resolved direct numerical simulation (PR-DNS) of the particle-laden flow. Such a simulation combines the standard Eulerian approach to computational fluid dynamics (CFD) with inclusion of particles via a variant of the immersed boundary method (IBM) and tracking of the particles movement using a discrete element method (DEM). Provided the used DEM allows for collisions of arbitrarily shaped particles, PR-DNS is based (almost) entirely on first principles, and as such it is a truly high-fidelity model. The downside of PR-DNS is its immense computational cost. In this work, we focus on three possibilities of alleviating the computational cost of PR-DNS: (i) replacing PR-DNS by PR-LES or PR-RANS, while the latter requires combining IBM with wall functions; (ii) improving efficiency of DEM contact solution via adaptively refined virtual mesh; and (iii) developing a method of model order reduction specifically tailored to PR-DNS of particle-laden flows.