Resolving the Structure of Turbulence in Rough Wall Channel Flows Using 3D, Time Resolved, Multiscale Velocity Measurements

Johns Hopkins University, Baltimore MD

Investigators

Abstract

PI: Katz, Joseph Proposal Number: 1438203 The proposed research aims to explore how turbulence is generated and sustained close to solid boundaries. It will use findings from very accurate experiments to clarify the way that energy is transferred in turbulent flows between the different regions of the flow. As such, this research would allow the development of correct models for the design of flow systems where solid walls are present, which are in fact the most common cases of turbulent flows in industry and the environment. Educational activities involve graduate and undergraduate students for the development and implementation of the proposed measurement system. There are also activities planned for Baltimore City high-school students to work yearlong in the PI?s laboratory as part of their required Research Practicum. This work will investigate how the roughness height, wavelength, spatial arrangement and uniformity, affect the generation of vortices, their evolution in time, their interactions with vortices away from the wall, and impact of these interactions on turbulence statistics. A rather comprehensive and non-trivial experimental approach is proposed: A 3D time-resolved tomographic PIV will resolve small-scale turbulence near the wall, while digital holographic microscopy (DHM) will be used to simultaneously observe the large scale structures away from the wall. The combined TPIV-DHM instrument would resolve 3.5 orders of magnitude of length scales.