Turbulent Flow through and over a Compact Three-Dimensional Model Porous Medium: An Experimental Study

James Kofi Arthur

doi:10.3390/fluids6100337

Abstract

There are several natural and industrial applications where turbulent flows over compact porous media are relevant. However, the study of such flows is rare. In this paper, an experimental investigation of turbulent flow through and over a compact model porous medium is presented to fill this gap in the literature. The objectives of this work were to measure the development of the flow over the porous boundary, the penetration of the turbulent flow into the porous domain, the attendant three-dimensional effects, and Reynolds number effects. These objectives were achieved by conducting particle image velocimetry measurements in a test section with turbulent flow through and over a compact model porous medium of porosity 85%, and filling fraction 21%. The bulk Reynolds numbers were 14,338 and 24,510. The results showed a large-scale anisotropic turbulent flow region over and within the porous medium. The overlying turbulent flow had a boundary layer that thickened along the stream by about 90% and infiltrated into the porous medium to a depth of about 7% of the porous medium rod diameter. The results presented here provide useful physical insight suited for the design and analyses of turbulent flows over compact porous media arrangements.

Highlights

The flow of fluids in composite porous-clear domains is a prevalent phenomenon in many natural and industrial applications
Attention is focused on the study of turbulent flow over a porous medium, and the concomitant effects on the flow through the coupled porous medium
In canopies of submerged aquatic vegetation, biogeochemical processes are regulated through unsteady inertial and turbulent exchanges of mass and momentum between the canopy and the ambient water [13]

Summary

Introduction

The flow of fluids in composite porous-clear domains is a prevalent phenomenon in many natural and industrial applications Such has been the focus of several research studies, covering both laminar and turbulent flow considerations [1,2,3,4,5,6,7,8,9,10,11]. Turbulent transport of wind within and above forest canopies plays an integral role in the atmospheric exchange of carbon dioxide ( forcing climate change [14]). They are important in making site assessments for architectural structures and wind turbine performance [15]. In the casting of alloys, turbulent flows generated due to electromagnetic stirring has been found to decrease channel formation in the mushy zone and associated patterns of segregation [17]

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Conclusion