Modeling and simulation of laminar flow through porous media have been essential for designing new devices and for predicting a myriad of natural and man-made processes, but must be developed further for turbulence modeling and simulation. Direct Numerical Simulation (DNS) is unfortunately limited to very simple configurations (e.g. "unit-cell" of regular and periodic permeable media) because of the enormous computational effort required for simulating the flow through realistic permeable media.
Technical Merit: Through the experimental and numerical investigation of turbulent flow through permeable media this study will: (1) build understanding of turbulent transport in permeable media; (2) generate an experimental data bank of results from distinct flow configurations for validating turbulence models; (3) fine tune two existing models for combined Reynolds/volume averaging (space-time and time-space) and verify their validity range; (4) develop a protocol for predicting the most appropriate averaging order and validate the protocol prediction results. This study addresses which characteristic(s) of permeable structures, i.e. porosity, permeability, form coefficient, best allow the determination of the most appropriate averaging order for a specific flow condition by experimentally investigating how large vortical structures are transported through permeable obstructions. The focus on large-scale vortical structures is motivated by their different local transport behavior depending on the characteristics of the permeable obstruction. The survival, or not, of the large-scale vortical structure as it flows through a particular obstruction is key to determining the most appropriate averaging order for modeling turbulent flow through a particular permeable medium. Tests with different permeable media aim at building a protocol for predicting the best suited averaging order based on permeable media and flow characteristics. Experiments on three simple porous media turbulent flow configurations (channel flow, steady jet, and unsteady jet) will produce a large data bank, essential for fine-tuning the models and validating their results, for verifying the protocol predictions vis-vis the most appropriate averaging order, and for benchmarking other experimental configurations. Model equations emanating from the space-time and from the time-space averaging sequence will simulate the experimental flows for fine-tuning the two models and determining their validity range. The comparisons will be based on values of turbulence characteristics (e.g., Reynolds stresses and turbulent kinetic energy) obtained from direct measurements of fluid velocity via digital particle image velocimetry (DPIV). The measurements will be performed externally and internally to the permeable medium (using optically transparent permeable structures) to determine the suitability of the easier external measurements for validation.
Broader Impact: This project will also seed a ground-breaking Innovative Design, Entrepreneurship and Engineering Application (IDEEA) program for the recruitment and retention of women and minorities in undergraduate and graduate engineering by focusing on a group of engineering devices and processes that can benefit directly from the application of the fundamental results obtained by this study. The program also brings about an important international component, for faculty and student exchange, involving collaboration with the Aeronautical Institute of Technology (ITA) in Brazil. This effort is in line with the strategic plan of the SMU School of Engineering and it will be supported by existing related campus programs.
