Dust, sand, and turbulence: Transport and feedback in the near-surface environment
Abstract
A key challenge in modeling dust and sand transport throughout the atmosphere lies in the fundamental particle-turbulence interactions which take place in the lower atmospheric boundary layer. The subsequent airborne spatial distributions, lofting mechanisms, and effects on the surface layer winds remain severely understudied and inhibit prediction in Army-relevant regions of the boundary layer. Phenomena such as preferential concentration, where particles dynamically collect in certain regions of the flow, and two-way coupling, where the suspension of the particles modifies the surrounding turbulent motions, can cause sharp deviations of near-surface concentrations and fluxes from those predicted by traditional, similarity-based parameterizations of passive scalars. While these mechanisms have been studied in numerous engineering contexts, these are typically restricted to low Reynolds numbers (i.e., low degrees of scale separation), and therefore much remains unknown about particle transport and feedback in systems with Reynolds numbers relevant to the atmospheric surface layer. The PIs propose a research program aimed at achieving a predictive understanding of dust and sand transport in the atmospheric surface layer, in order to start bridging the gap between the existing knowledge on particle-turbulence interactions, which have been traditionally investigated at the micro-scale, and atmospheric dynamics relevant at the macro-scale. The overall strategy is to combine detailed laboratory observations of turbulence/dust interaction with large-scale and high-resolution numerical simulations to inform near-surface transport parameterizations which are crucial for accurately connecting saltation rates and airborne dust/sand concentrations Ð something which continues to plague surface dust emission models. The proposed work centers around several key questions relevant to the Aeolian transport process, with long-term goals of ultimately improving predictions of near-surface, electromagnetic-based communications, long-range dust and mineral transport, surface environmental conditions, and geomorphology. Despite their relevance, such questions have so far remained unanswered due to a lack of appropriate tools and focused multi-disciplinary efforts. These questions are: (1) What transport mechanisms control the airborne lifetime of sand and dust grains, and how does this influence their vertical distribution? (2) How important is two-way coupling in determining suspension concentrations of dust and sand? (3) How do suspended dust and sand modify surface-air exchange of momentum and heat? PI Coletti will oversee the experimental component of the work, utilizing facilities housed at the University of Minnesota. A large, temperature-controlled ...
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 06, 2018
- Source ID
- W911NF1710366
Entities
People
- David H Richter
Organizations
- Army Contracting Command
- United States Army
- University of Notre Dame