At FESLab, we pursue a wide range of research in theoretical, experimental, and computational fluid mechanics. We focus on fundamental problems that are motivated by strong practical applications in the field of energy production or conservation. Through our research, we seek advances in fundamental understanding that have the potential to drive paradigm shifts, thereby enabling key advances in technology.

While our interests revolve around uncovering and understanding fundamental fluid phenomena, to make this possible, we often find ourselves developing new theoretical approaches, numerical techniques, experimental strategies, and even new instrumentation for fluid dynamics research. 

Space-Based Experiments on Cohesive Sediment

Accurate sediment models are essential to predict the environmental dynamics of lakes, estuaries, the coastal ocean, fisheries, and benthic habitats, and they play a central role in hydrocarbon exploration.

An ideal limit for the performance of a large, fully-developed wind farm

Wind turbines are often deployed in arrays of hundreds of units, where interactions lead to drastic losses in power output. Remarkably, while the theoretical `Betz’ maximum has long been established for the output of a single turbine, no corresponding theory appears to exist for a generic, large-scale energy extraction system.
We develop a model for an array of energy-extraction devices of arbitrary design and layout, first focusing on the fully-developed regime, thereby establishing an upper bound on the performance of a large wind farm. This is found to be several times larger than the output of existing arrays.

 

A simple and complete two-interface model for spatially developing flow in rigid and flexible canopies

At the front of a canopy, flow deceleration is associated with strong vertical fluxes of mass and momentum. Accurately describing this region is important in many applications, including terrestrial and aquatic vegetation, as well as large wind farms.

We build a simple and complete model, by separating the flow in three horizontal layers. These comprise the canopy, the overlying boundary layer, and the outer flow. Our  model quantitatively describes the flow velocities and boundary layer heights in developing canopy flows, and successfully accounts for the effect of canopy flexibility.

Modelling wind turbine wakes using the turbulent entrainment hypothesis

We develop a model, for a wind turbine wake, by relying on a simple and general turbulence parameterization, namely the entrainment hypothesis. Without assuming similarity, we derive an analytical solution for a circular turbine wake, which predicts a far-wake radius increasing with x1/3, and is consistent with field measurements and fundamental turbulence studies.

Conduino

Conduino: an affordable and accurate conductivity probe for density measurements in stratified flows

In stratified flow experiments, conductivity (combined with temperature) is often used to measure density. The probes typically used can provide very fine spatial scales, but can be fragile, expensive to replace, and sensitive to environmental noise.

We propose using micro-USB cables as the actual conductivity sensors, and introduce a custom electronic board for simultaneous acquisition from 4 sensors, with performance comparable to typical existing probes. Full details to make your own Conduino are at https://github.com/feslab/conduino. If you are interested in a pre-assembled version, please contact conduino [at] gmail [dot] com.

Effects of trace amounts of surfactants on drag reduction for superhydrophobic surfaces

Large drag reductions (of the order of 50% or more) have been measured for laminar flows over superhydrophobic surfaces (SHS), making them attractive for applications in pipelines, ships and submarines. However, experiments involving turbulent flows (typical of these applications) have often yielded limited and erratic drag reductions. A complete explanation for this issue had so far proved elusive. 

We propose that trace amounts of surfactants (unavoidable in the environment and in large-scale experiments) might yield poor performances of SHS, by producing Marangoni stresses when the edges of the SHS pattern are not aligned with the local flow velocity. 

Our findings have appeared in Proceedings of the National Academy of Sciences.

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