Overview
My intellectual interests and passions revolve around the desire to understand and predict the beautifully complex, enigmatic motion of turbulent flows, and their role in natural and engineered systems. The environment provides one of the richest settings motivating research on this topic, with far reaching implications for understanding atmospheric clouds, oceans, global warming, among many others. To address the profound complexity of turbulence I utilize methods from applied mathematics, statistical and theoretical physics, and high-performance computing. I also work closely with experimentalists, being convinced that a multifaceted, collaborative approach is required for significant progress on this very challenging subject.
Turbulent flows are inherently multiscale, and in environmental contexts they involve motion on spatial scales ranging from kilometers down to micrometers. Large-scale numerical simulations of environmental flows cannot resolve all of the scales, and so the unresolved scales must be parametrized. However, the nonlinear physics of the unresolved processes are often poorly understood, leading to great uncertainty in their parameterizations. This challenge is a key motivation for my own research, namely to understand the nonlinear physics of these small-scale processes and then to develop models that capture them for use in large-scale numerical models.
Before joining the Duke University faculty, Dr. Bragg was a postdoctoral associate in the Applied Mathematics and Plasma Physics Group at the Los Alamos National Laboratory. Prior to that, he was a postdoctoral associate in the Sibley School of Mechanical and Aerospace Engineering at Cornell University. Dr. Bragg obtained his PhD in Theoretical Fluid Dynamics from Newcastle University in England.
Current Appointments & Affiliations
Recent Publications
Gas Transfer Across Air-Water Interfaces in Inland Waters: From Micro-Eddies to Super-Statistics
Journal Article Water Resources Research · November 1, 2024 In inland water covering lakes, reservoirs, and ponds, the gas exchange of slightly soluble gases such as carbon dioxide, dimethyl sulfide, methane, or oxygen across a clean and nearly flat air-water interface is routinely described using a water-side mean ... Full text CiteUnderstanding the effect of Prandtl number on momentum and scalar mixing rates in neutral and stably stratified flows using gradient field dynamics
Journal Article Journal of Fluid Mechanics · August 27, 2024 Recently, direct numerical simulations (DNS) of stably stratified turbulence have shown that as the Prandtl number is increased from 1 to 7, the mean turbulent potential energy dissipation rate (TPE-DR) drops dramatically, while the mean turbulent kinetic ... Full text CiteHeterogeneous Land-Surface Effects on TKE and Cloud Formation: Statistical Insights From LES Cases
Journal Article Journal of Geophysical Research: Atmospheres · June 28, 2024 This manuscript investigates the impact of land-surface heterogeneity on atmospheric processes by comparing 92 large-eddy simulation cases over the Southern Great Plains, leveraging high-resolution spatially heterogeneous and homogeneous land-surface field ... Full text CiteRecent Grants
CAREER: Sheared stratified turbulence: novel mechanisms and models of complex wave-vortex interactions that impact our environment
ResearchPrincipal Investigator · Awarded by National Science Foundation · 2021 - 2025Development and application of a wall model for the dust-laden atmospheric boundary layer
ResearchPrincipal Investigator · Awarded by University of Notre Dame · 2022 - 2025Implications of heterogeneity-aware land-atmosphere coupling in the predictability of precipitation extremes
ResearchCo-Principal Investigator · Awarded by National Oceanic and Atmospheric Administration · 2022 - 2024View All Grants