"Dr. Pulletikurthi's research focus is on investigating the applications of turbulence flow control in climate change resiliency projects, particularly those that involve the integration of CO2 capturing with wind turbines, leveraging marine ecosystems as sinks for CO2, and utilizing bio-inspired structures for anti-fouling and noise reduction applications in autonomous underwater and aviation vehicles. 

To achieve these goals, he uses a combination of numerical and experimental techniques."

The projects outlined below discuss the fundamental study of fluid physics of turbulent and laminar flows using numerical and experimental methods. The methodologies applied to analyze the flow data are low-order modeling techniques (Proper Orthogonal Decomposition, POD), Gaussian filtering technique, Complex demodulation techniques, and spectral analysis

Proliferation of coherent vortical structures and role of energetic large-scale motions contributing to heat fluxes

Direct numerical simulations (DNS) of a turbulent channel flow with a passive scalar at a frictional Reynolds number, 394, with blowing perturbations is carried out. The blowing is imposed through five spanwise jets located near the upstream end of the channel. Perturbations led to the proliferation of coherent vortical structures extracted using λ2 criterion which are the reason for observation of hot and cold spots (details). In this study, low-order modeling technique, Proper-orthogonal decomposition (POD), is used to extract the energetic large-scale motions which contributed to the enhanced heat transfer (details). 

Upstream perturbations effect on large-scale field and characterization of perturbations to excite LSM

Adaptive Gaussian filtering based on two-point correlations is used to extract spatial large-scale motions,  ≥ 2h , h is channel height. It's been observed that perturbations led to the generation of ring-type vortices which are crucial in enhancing the sweeps and ejection events, therefore mixing. Turbulence production indicated that there is a secondary zone of turbulence production due to the shear layer formed by the interaction of perturbations and channel flow. Also, it is observed that the jet perturbation spacing and diameter are related to the excited LSM wavelengths. (details)

Interaction of low-level jets with wind turbines : the underlying mechanism in the energy entrainment

A synthetic LLJ, low-level jet, a global atmospheric phenomenon knows for it's high wind velocities and low turbulence intensity, is created in a Eiffle Type Wind tunnel at University of Illinois at Urbana-Champaign. It has been observed that positive shear and negative shear regions are responsible for increasing the energy flux entrainment--enhanced power production in second row of wind turbines (details)

Novel sustainable filter for virus filtration and inactivation

In this study, we have proposed a novel design for a filter for enhanced virus filtration, better breathability, and virus inactivation over time. The filter is called Hy–Cu named after its (Hy) hydrophobic properties and another significant layer comprises of copper (Cu). The breathability (pressure drop across filter) of Hy–Cu is tested and compared with widely used surgical masks and KN95 masks, both experimentally and numerically. The results show that the Hy–Cu filter offers at least 10% less air resistance as compared to commercially available masks. The experimental results on virus filtration and inactivation tests using MS2 bacteriophage (a similar protein structure as SARS-CoV-2) show that the novel filter has 90% filtering efficiency and 99% virus inactivation over a period of 2 h. This makes the Hy–Cu filter reusable and a judicious substitute to the single use masks.  (details)

On the development of low frequency structures in near and far laminar wakes

An immersed boundary method is used to simulate flow past an elliptic cylinder of aspect ratio, 0.4, for laminar Reynolds number, 130. The objective of this project is to study the temporal and spatial source of low-frequency unsteadiness (secondary von Karman vortex street) in the far wake of cylinder. It has been observed that the temporal source (analyzed using the complex demodulation technique) of the low-frequency unsteadiness is the saturated state of the wake development and spatial source is the periodic nature of the saturation region. (details)

Analysis and characterization of momentum and thermal wakes of elliptical cylinders

Flow past a bluff body is simulated (immersed boundary method) for various laminar Reynolds numbers for varied aspect ratios of elliptical cylinders to study the unsteady near and far wakes. It has been shown that the shear layer instabilities from the transition region led to the onset of secondary von Karman vortex shedding. (details