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Research

Overview

Our research focuses on measurement and prediction of environmental boundary-layers (EBLs). EBLs include atmospheric boundary-layers (ABLs), ocean and lake surface boundary-layers—also called the surface mixed layer—(SBL), and benthic boundary-layers (BBLs), as well as river and tidal flows. Generally, EBLs are characterized by rough, heterogeneous surfaces, multi-scale topography or bedforms, tall vegetation and variations in surface heat and scalar fluxes, all of which impact the turbulence dynamics and surface fluxes to varying degrees. The study of EBL dynamics utilizes numerical techniques such as large-eddy simulation (LES) and experimental boundary-layer turbulence studies, both at the field scale and in the laboratory. Applications include most problems dealing with air and water resource sustainability, land-atmosphere and air-water interactions, and renewable energy.

Specific Questions

topocnpylakeIn particular, we focus on complex environmental flows and turbulence transport in separated or wake embedded boundary layer flows. Examples include flow over canopy transitions, over and around buildings, wind turbines, over steep topography, and in the presence of surface wave fields. The goal is to better understand interfacial fluxes of momentum, heat, water vapor, and trace gasses, and provide more reliable inputs to ecosystem,  lake, climate, weather, pollution, and renewable energy resource models; to improve micrometeorological flux measurements; and to test and improve LES sub-grid scale and land surface boundary parameterizations for EBL simulations over complex surfaces.

Methods

We conduct research using the experimental facilities and computational resources of IIHR—Hydroscience & Engineering, employing an interdisciplinary approach and a combination of:

  • Controlled experimental turbulence research in wind tunnels and water channels (using hot-wire anemometry, laser Doppler velocimetry (LDV), and particle image velocimetry (PIV)),
  • Full-scale field measurements (using sonic and acoustic Doppler velocimetry (ADV) and Doppler LIDAR), and
  • Numerical modeling (using Mesoscale atmospheric models and LES).

We use measurements and simulations conducted at a range of scales along with perspectives from earth and engineering sciences to improve fundamental understanding, as well as to develop useful models that can be employed by scientists, engineers, planners, and policy makers.

Examples and Applications

Specific projects include studies of how canopy and topographic induced wakes affect momentum, evaporation, and trace gas fluxes at the air-land and air-water interfaces for ecosystem, lake and wetland modeling; investigation on how deforestation patterns in the Amazon rainforest may be parameterized in weather and climate models; and studies of wind farm-atmosphere interactions to understand the impact of atmospheric stability on wind turbine wakes and wind farm configuration effects on ABL dynamics and surface fluxes. Understanding how landscape heterogeneity affects momentum flux and transport of heat, moisture, and trace gases is important for developing physics-based parameterizations for large-scale weather, climate, hydrologic, and wind resource assessment models, as well as for interpreting measurements, which may be spatially or temporally limited.


Research Support

This research is supported by the National Science Foundation, NASA, and USGS. Additional support is provided by the Iowa Energy Center. Computational resources are provided by IIHR—Hydroscience & Engineering’s Research Computing Services.

Last modified on February 14th, 2016
Posted on September 24th, 2014