Highly-Resolved LES of the Stable Boundary Layer Over Terrain

Conference · Wed May 31 04:00:00 EDT 2000

OSTI ID:792809

Calhoun, R ^[1]; Cederwall, R T; Stevens, D; Street, R

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1. LLNL

One of the most important scenarios for atmospheric modelers is the stable boundary layer (SBL). Airborne material released near the ground will likely be trapped near the ground in high concentrations due to the reduced dispersion in the SBL. Hence the SBL is often the worst case scenario for studies of health impacts from routine or accidental release of toxic materials to the atmosphere. Unfortunately the SBL is very challenging to understand and model correctly. There is also a limited number of field studies with which to verify models, although recent studies (such as CASES-99) are promising. It is difficult for traditional Reynolds-averaged models of turbulence to capture the weak, spatially- and temporally-varying fluctuations that contribute to dispersion the SBL. Large-eddy simulation (LES) has become a promising approach study the SBL because much of the dynamical structure is explicitly resolved and allowed to develop according to the full equations of motion. The presence of topography further complicates the simulation of SBL flows. The drainage flows that develop as the surface cools must be resolved, along with their interaction with other drainage flows of varying scales and the main forcing (synoptic scale) flow. In this study, we have used LES techniques to simulate flows in complex terrain during the development of the SBL at night. We have begun to evaluate the effects of resolution on the simulations, though this effort is continuing at the time of this writing. Simulations are conducted for the area around Salt Lake City, where several field activities are planned for the future. The study will be extended to the small scale terrain associated with the CASES-99 experiment, and comparisons made with observations.

• Research Organization: Lawrence Livermore National Lab., CA (US)
• Sponsoring Organization: USDOE Office of Defense Programs (DP) (US)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 792809
• Report Number(s): UCRL-JC-137628
• Country of Publication: United States
• Language: English

Related Subjects

17 WIND ENERGY
BOUNDARY LAYERS
COMPLEX TERRAIN
DRAINAGE
EQUATIONS OF MOTION
FLUCTUATIONS
LAKES
RESOLUTION
SIMULATION
TOPOGRAPHY
TOXIC MATERIALS
TURBULENCE