Particle behavior in a turbulent flow within an axially corrugated geometry

Ghulam Mustafa Majal,Lisa Prahl Wittberg,Mihai Mihaescu

doi:10.1177/16878140211036019

Ghulam Mustafa Majal, Lisa Prahl Wittberg + Show 1 more

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https://doi.org/10.1177/16878140211036019

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Abstract

In this numerical study particle behavior inside a sinusoidal pipe geometry is analyzed. The 3D geometry consists of three identical modules, with a periodic boundary condition applied to the flow in the stream wise direction. The incompressible, turbulent gas flow is modeled using a Large Eddy Simulation (LES) approach. Furthermore, the particle dynamics are simulated using a Lagrangian point force approach incorporating the Stokes drag and slip correction factor. Four different sizes of particles, corresponding to a Stokes number less than unity, are considered along with two different inflow conditions: continuous and pulsatile. The pulsatile inflow has an associated flow frequency of 80 Hz. The fluid flow through the sinusoidal pipe is characterized by weak flow separation in the expansion zones of the sinusoidal pipe geometry, where induced shear layers and weak recirculation zones are identified. Particle behavior under the two inflow conditions is quantified using particle dispersion, particle residence time, and average radial position of the particle. No discernible difference in the particle behavior is observed between the two inflow conditions. As the observed recirculation zones are weak, the particles are not retained within the cavities for a long duration of time, thereby reducing their likelihood of agglomerating.

Highlights

Corrugated geometries have been studied extensively with regards to their effect on fluid mixing,[1,2,3] mass transfer,[4,5] and heat transfer.[6,7,8,9,10] By corrugated geometries we are referring to geometries with successive expansions and contractions
In order to get an insight into the particle behavior within the sinusoidal pipe geometry the particle dispersion, residence time within each module and the average radial position of a particle within a module are considered
Histogram plots associated with the particle residence time highlight that the vast majority of the particles are not retained in the domain for a long duration of time

Summary

Introduction

Corrugated geometries have been studied extensively with regards to their effect on fluid mixing,[1,2,3] mass transfer,[4,5] and heat transfer.[6,7,8,9,10] By corrugated geometries we are referring to geometries with successive expansions and contractions. It has been reported that both the mass and heat transfer characteristics of such geometrical configurations were better than their straight channel counterparts based on the Sherwood and Nusselt number calculated for different Reynolds number. This has been credited to the intrinsic flow structures found within such corrugated geometries which contribute toward better fluid mixing. A larger pressure drop has been observed for corrugated geometries as compared to straight channel geometries.[7]

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