Environmental  Fluid  Mechanics  @  Princeton

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Our paper in Nature is featured in a Princeton news article

Our City Reader project wins a
Beyond Bauhaus Prize

Our paper on urban heat islands during cold waves featured in Science Daily

ABL Parameterization

Sensor Networks

Large Eddy Simulations

Multiscale Atmospheric Simulations

Urban Micrometeorology and Energy Studies

Turbulence Structure

The Environmental Fluid Mechanics Research Group aims to understand the fundamental dynamics of flow and transport in environmental system and, consequently, to improve our ability to model and monitor these systems. Environmental Fluid Mechanics have a wide range of impacts on many environmental problems related to climate change, air quality, hydrology, ecology, and sustainable development, to name a few.

From the effect of millimeter-scale turbulence on water condensation around submicron particles in clouds to the global-scale atmospheric and oceanic currents that control the climate and the weather on earth, the flows of environmental fluids interact with other physical, chemical, and  biological processes to shape the world around us. While we try, and sometimes succeed, in developing accurate mathematical models for these processes based on first principles, the strong interaction of the various processes and scales make it impossible to have a "model of everything" that can capture all the complexities of our environment. In addition, the engineering of manmade systems and their interaction with the natural systems further complicate the task.

The alternative approach that is used today is to try too isolate one or a set of processes and study them, analytically numerically or experimentally, while parameterizing their interaction with the other, neglected, processes. Global climate models for examples parameterize the effect of geophysical turbulence; air quality models often parameterize the physical and chemical interactions with the earth surface, and cloud models parameterize all the small scale physico-chemical processes. These parameterizations are of course themselves simple models for the processes we elect not to model in detail.

In the Environmental Fluid Mechanics Research Group at Princeton, we seek to develop models for the dynamics of geophysical flow and transport at scales that are relevant to environmental problems, i.e. from millimeters up to a few kilometers. For each problem, we seek the best combination of analytical, numerical, and experimental tools to find the appropriate solutions.

On the analytical side, we use simplified forms of the governing equations (the Navier-Stokes equations) and similarity theories (such as the Monin-Obukhov Similarity Theory) to focus on the most important dynamics in environmental flows.


On the numerical side, we mostly use the large eddy simulation technique (LES), which solves only for the largest turbulent scales, to simulate environmental flows and transport in complex domains, (see figure to the right). We are also very actively involved in improving the parameterization of unresolved turbulence in LES and the parameterizations, in coarser geophysical models, of unresolved physics such as surface variability (see figure below), atmospheric boundary layers , etc

Contours of the Smagorinsky coefficient (rough
indicator of the turbulence intensity) around a building


Velocity deviation from its horizontal mean in an LES over a roughness transition. We can discern three zones, the internal boundary layer (IBL), the zone of upstream plume(s), and the mixed zone above the blending height

On the experimental side, we use in-situ point sensors, remote sensors, and distributed sensing networks to measure the wide range of spatial and temporal scales of atmospheric flows and their interaction with the surface. The long-term aim of our efforts is to combine experimental data and simulations and to assimilate them them into integrated frameworks to elucidate environmental dynamics and guide environmental policy.


Met station setup at roof of the Engineering Quadrangle - Princeton University

Measuring surface fluxes using the eddy covariance technique on the plaine-morte (work with the EFLUM lab at EPFL)

Measuring heat & momentum fluxes using scintillometers on the roofs of EPFL campus (work with the EFLUM lab at EPFL)



last update on: August 05, 2011 14:02,  contact webmaster

Contact Information

Elie Bou-Zeid
Department of Civil & Environmental Engineering
Princeton University, C326 EQuad
Princeton, NJ 08544, USA

phone  :  +1-609-258-5429
fax        :  +1-609-258-2799
email   :  
web      :  http://efm.princeton.edu/