Chamorro embarks on new study to investigate mechanics of dust devils
MechSE Associate Professor Leo Chamorro and Associate Professor Yulia Peet of Arizona State University are continuing a history of collaboration with a new study: characterizing and quantifying mechanisms responsible for the production of dust devils. Similar in appearance to tornados, dust devils are produced from bouts of turbulent flow and convective vortices that entrain dust.
The pair’s study, which has been funded by the National Science Foundation, will employ “evaluation of the turbulent flow statistics, Lagrangian properties of the sediment particles, and the forces involved with the particle/fluid interaction” to construct a comprehensive picture of the mechanisms that govern dust devils.
The National Weather Service defines a dust devil as a dust-filled vortex caused by strong surface heating. Dust devils can occur when a localized pocket of air heated by the ground rises quickly through cool air above it. The rapid movement and temperature differential can cause the air to start spinning; as it spins, dust gets swept up and becomes entrained.
However, the actual fluid mechanics that drive this phenomenon have not been characterized. The researchers define two gaps in the current knowledge surrounding sediment entrainment and transport in turbulent flows: the lack of 1) experimental validation of numerical multiphase flow models and 2) detailed characterization of entrainment processes in complex inhomogeneous flows.
To address this gap experimentally, the team will employ three-dimensional particle image velocimetry combined with particle-tracking velocimetry techniques. Their planned simulations will involve a four-way coupled multiphase flow approach in a wall-resolved Large Eddy Simulations (LES) framework that integrates a Discrete Element Momentum (DEM) module for particle tracking.
“A significant outcome of the proposed research will be detailed quantitative information about the correlations between the sediment fluxes and the carrier phase,” the team wrote of their project. “[We] intend to use these data in follow-up work to build accurate and robust non-equilibrium sediment flux models for non-canonical flow configurations, which currently do not exist.”
The team will also collaborate with the Louis Stokes Alliance for Minority Participation at Arizona State and the Illinois Scholars Undergraduate Research Program at UIUC to help students navigate both transitions between undergraduate and graduate STEM programs and post-secondary education.
“These models will transform the predictive capabilities of current weather and climate codes,” Chamorro said. “They will result in more reliable predictions and mitigation of hazardous weather events, fugitive dust pollution, and the effect of anthropogenic activities on climate change, among others.”