NSF-BSF: Multiphase transport processes with phase change in stratified hypersaline lakes: A combined computational and field investigation

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Earth's crust contains numerous large-scale salt deposits that are up to a kilometer thick. These deposits are of great importance for engineering applications such as mineral extraction and oil and gas exploration, and for understanding the processes that have governed the oceans throughout Earth's history. However, the formation and structure of these large salt deposits are at present poorly understood. Today, the Dead Sea is the only deep lake in the world in which salt crystals form and create a growing deposit on the seafloor. This dynamic environment provides a unique natural laboratory for exploring the multiphase transport processes with phase change that create such salt deposits. This project will undertake a comprehensive investigation that combines an extensive field campaign by the Geological Survey of Israel with detailed large-scale computer simulations and theoretical analysis at the University of California, Santa Barbara. The research will train US engineering and geology students in the interdisciplinary areas of environmental model development, computational multiphase fluid dynamics, and large-scale simulations on parallel computer architectures. Student exchanges will take place between UCSB and the Dead Sea Observatory, and the investigators will hold lecture series at both institutions. An international workshop on the physical transport processes governing the Dead Sea is planned. This project will explore and quantify the nonlinear interplay of the convective and diffusive transport of heat and salt. The project will explore how this transport is modulated by (1) phase change between dissolved and crystalline salt within the lake; (2) radiative heating/cooling, evaporation/salt rejection and wind stresses at the lake's surface; and (3) inflow of freshwater, sediment and/or brine. The governing dimensionless parameters will be identified, along with the quantitative ranges that apply to the Dead Sea, and the respective balances that govern the dynamics. In this way, the project will obtain quantitatively accurate scaling laws for these processes, and enable predictions for the evolution of the Dead Sea under a variety of different environmental forcings. Results will provide a predictive tool for managing water resources and useful information for advancing technologies related to mining and hydrocarbon exploration.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.