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Peter Hamlington
Associate Professor, CU Boulder Rady Mechanical Engineering
Friday, October 29 | 12:00 P.M. | Hybrid - AERO 114 & Zoom Webinar

Abstract: Buoyant jets and plumes are found in a variety of natural and engineering contexts, including industrial burners, wildfires, hydrothermal vents, and volcanic plumes. Prior research has shown that these flows “puff” at a frequency that depends on the balance of momentum and buoyancy fluxes at the inlet, as parametrized by the Richardson number. Experiments have revealed the existence of scaling relations between the Strouhal number of the puffing and the inlet Richardson number, but geometry-specific relations are required when the characteristic length is taken to be the diameter (for round inlets) or width (for planar inlets).

Here we use the hydraulic radius of the inlet as the characteristic length to obtain a single Strouhal–Richardson scaling relation for a variety of inlet geometries over Richardson numbers that span three orders of magnitude. We use adaptive mesh numerical simulations to compute puffing Strouhal numbers for circular, rectangular (with three different aspect ratios), triangular and annular high-temperature buoyant jets and plumes over a range of Richardson numbers. We then combine these results with prior experimental data for round, planar and rectangular buoyant jets and plumes to propose a new scaling relation that describes puffing Strouhal numbers for various inlet shapes and for hydraulic Richardson numbers spanning over four orders of magnitude. Finally, we show that very high spatial resolutions are required to accurately capture the near-field structure and dynamics of large-scale plumes, particularly with respect to the development of fundamental flow instabilities.

Biography: Dr. Peter Hamlington is an Associate Professor, Associate Chair, and Vogel Faculty Fellow in the Paul M. Rady Department of Mechanical Engineering and the Environmental Engineering Program at CU Boulder, with a courtesy appointment in Smead Aerospace and a joint appointment with NREL. Research in his group, the Turbulence and Energy System Laboratory (tesla.colorado.edu), is focused on understanding and modeling turbulent flows in both engineering and geophysical problems using large eddy and direct numerical simulations. Dr. Hamlington and his group have used numerical simulations for the study of a broad range of applications, including unsteady, boundary layer, chemically reacting, and oceanic flows, as well as boundary layer flows relevant to renewable energy systems. The primary emphasis in many of these studies has been to understand fundamental flow physics and to use the resulting insights for the development of physically accurate, computationally efficient models for large-scale simulations of real-world problems. Dr. Hamlington has a BA in Physics from the University of Chicago and MS and PhD degrees in Aerospace Science from the University of Michigan, Ann Arbor.