Gas-Particle Dynamics in High-Speed Flows

High-speed disperse multiphase flows are present in numerous environmental and engineering applications with complex interactions between turbulence, shock waves, and particles. Compared to its incompressible counterpart, compressible two-phase flows introduce new scales of motion that challenge simulations and experiments. This review focuses on gas-particle interactions spanning subsonic to supersonic flow conditions. An overview of existing Mach number-dependent drag laws is presented, with origins from 18th-century cannon firings, and new insights from particle-resolved numerical simulations. The equations of motion and phenomenology for a single particle are first reviewed. Multi-particle systems spanning dusty gases to dense suspensions are then discussed from numerical and experimental perspectives

Direct numerical simulation of noise suppression by water injection in high-speed flows

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143117/1/6.2017-1700.pd

Adjoint-based sensitivity analysis of ignition in a turbulent reactive shear layer

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143014/1/6.2017-0846.pd

A volume-filtered description of compressible particle-laden flows

In this work, we present a rigorous derivation of the volume-filtered viscous compressible Navier–Stokes equations for disperse two-phase flows. Compared to incompressible flows, many new unclosed terms appear. These terms are quantified via a posteriori filtering of two-dimensional direct simulations of shock-particle interactions. We demonstrate that the pseudo-turbulent kinetic energy (PTKE) systematically acts to reduce the local gas-phase pressure and consequently increase the local Mach number. Its magnitude varies with volume fraction and filter size, which can be characterized using a Knudsen number based on the filter size and inter-particle spacing. A transport equation for PTKE is derived and closure models are proposed to accurately capture its evolution. The resulting set of volume-filtered equations are implemented within a high-order Eulerian–Lagrangian framework. An interphase coupling strategy consistent with the volume filtered formulation is employed to ensure grid convergence. Finally PTKE obtained from the volume-filtered Eulerian–Lagrangian simulations are compared to a series of two- and three-dimensional direct simulations of shocks passing through stationary particles

A computational study of the effects of multiphase dynamics in catalytic upgrading of biomass pyrolysis vapor

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145281/1/aic16184.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145281/2/aic16184_am.pd

Volume filtered FEM-DEM framework for simulating particle-laden flows in complex geometries

We present a computational framework for modeling large-scale particle-laden flows in complex domains with the goal of enabling simulations in medical-image derived patient specific geometries. The framework is based on a volume-filtered Eulerian-Lagrangian method that uses a finite element method (FEM) to solve for the fluid phase coupled with a discrete element method (DEM) for the particle phase, with varying levels of coupling between the phases. The fluid phase is solved on a three-dimensional unstructured grid using a stabilized FEM. The particle phase is modeled as rigid spheres and their motion is calculated according to Newton's second law for translation and rotation. We propose an efficient and conservative particle-fluid coupling scheme compatible with the FEM basis that enables convergence under grid refinement of the two-way coupling terms. Efficient algorithms for neighbor detection for particle-particle collision and particle-wall collisions are adopted. The method is applied to a few different test cases and the results are analyzed qualitatively. The results demonstrate the capabilities of the implementation and the potential of the method for simulating large-scale particle-laden flows in complex geometries.Comment: 15 pages, 11 figure

Verification of Eulerian–Eulerian and Eulerian–Lagrangian simulations for turbulent fluid–particle flows

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139111/1/aic15949_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139111/2/aic15949.pd

Direct comparison of Eulerian–Eulerian and Eulerian–Lagrangian simulations for particle‐laden vertical channel flow

Particle‐laden flows in a vertical channel were simulated using an Eulerian–Eulerian, Anisotropic Gaussian (EE‐AG) model. Two sets of cases varying the overall mass loading were done using particle sizes corresponding to either a large or small Stokes number. Primary and turbulent statistics were extracted from these results and compared with counterparts collected from Eulerian–Lagrangian (EL) simulations. The statistics collected from the small Stokes number particle cases correspond well between the two models, with the EE‐AG model replicating the transition observed using the EL model from shear‐induced turbulence to relaminarization to cluster‐induced turbulence as the mass loading increased. The EE‐AG model was able to capture the behavior of the EL simulations only at the largest particle concentrations using the large Stokes particles. This is due to the limitations involved with employing a particle‐phase Eulerian model (as opposed to a Lagrangian representation) for a spatially intermittent system that has a low particle number concentration.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155968/1/aic16230_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155968/2/aic16230.pd