Author(s): Souta Nakajyo; Takaaki Shigematsu; Kosei Takehara; Gozo Tsujimoto
Linked Author(s):
Keywords: Porous Media; Turbulence; PIV; PTV; Refractive Index Matching Method
Abstract: The study of flow through porous media has garnered much atter1tion because of its wide application to various fields in science and industry. In the field of hydraulic and coastal engineering, permeable structures have been an important research object from the view point of a simultaneous focus on both water control and water utilization. Recently, with the rising awareness of water environments, there’s been an increase in research on the transport mechanisms of substances such as oxygen and nutrients around porous media. In this study, unidirectional fluid motion through a porous media is measured using a particle tracking velocimetry (PTV) technique with high time and space resolution and a refractive index matching method to quantitatively understand the process of the generation of turbulence. We aimed to understanding the quasi- three dimensional turbulent structures inside and in the vicinity of porous media by measuring two—dimensional fluid motion in 7 different sections. On the basis of the measurement results, the characteristics of temporal and spatial fluctuations were examined and spectra and turbulent properties were then calculated. As a result of our detailed analysis of the measured velocity fields, the process of the generation of turbulence within the process whereby laminar unidirectional flow goes through a porous media becomes clear and a quantitative prediction of turbulence possible. The coefficient of kinematic eddy viscosity based on the Boussinesq hypothesis is also obtained in porous media and in the wake region.
Year: 2007