Mesoscale to Microscale Coupling Using Continuous Eddy Simulation

University Of Wyoming, Laramie WY

Investigators

Abstract

Atmospheric numerical modeling simulations are based on techniques that are most relevant to the scales that are being simulated. Models that are built to study wind flow through urban buildings use a different methodology as ones that simulate weather at continental scales. It has been a standing challenge in the field on how to bridge these scales. This project takes research that has been conducted in the engineering discipline and applies it to atmospheric modeling, with a goal of better simulating the motions closest to the Earth’s surface. The work has particular relevance to wind energy production, but also to weather forecasting in general. A postdoctoral research scientist will play a large role in the project, thereby providing training for the next generation of scientists. This project is for the application of a newly-developed mathematical method to the “Terra-Incognita” problem of coupling mesoscale and microscale atmospheric models. The Continuous Eddy Simulation (CES) method was developed for engineering problems that span the Reynolds-averaged Navier Stokes (RANS) and Large Eddy Simulation (LES) modes. In meteorology, this relates to the difficulty in running models on simulations at intermediate grid spacing, where there are inconsistencies between equations and the scaling of characteristic time and length scales. CES is able to stably respond to changing conditions as implied by grid and Reynolds number variations. The work plan is focused on two tasks with subprojects: 1. Implement CES as a microscale model in the Weather Research and Forecasting (WRF) model environment. The integration will need to demonstrate the ability to correctly cover almost RANS and almost resolving LES regimes, and consistently redistribute resolved and modeled modes in response to grid variations. CES-WRF will be validated using an existing LES simulation. CES-WRF will also be used to validate the Townsend Eddy Theory (TET), which is a recently developed conceptual model for the structure of wall-bounded turbulent flows. 2. Validate CES as mesoscale WRF. CES-Microscale/Mesoscale (MIME) will be evaluated for a wide range of domain sizes and coarse grids to verify the functioning of the CES mode redistribution mechanism. A variety of coupling cases will be studied. 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.