RESEARCH INTERESTs

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  Flow and Heat Transfer in an Open Top Chamber
  Open Top Chambers (OTCs) have been intensively used in the past to assess the effects of air pollutants on plants. Recently, a large scale project has been launched to design and build temperature-controlled OTCs in spruce forest in northern Minnesota to assess the response of the ecosystems to increases in temperatures and exposures to elevated atmospheric CO2. Heat transfer and fluid flow calculations were performed to assess the heater powers, the frustum design, the wind ingress, the airflow, and the temperature distribution inside the chamber. For more, check the video here.
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  Biologically inspired flow sensors
  Amazing sensors design can be found in nature. For instance, seals are able to detect the hydrodynamic trail of a swimming fish from more than one hundred feet away with its whiskers (see here). Fish uses a complex, multi-branched, mechanoreceptive organ called the lateral line to detect the motion of water in their immediate surroundings. In particular, fish has a long tube embedded immediately under the skin on each side of its body. In most fish, pore-like openings are regularly distributed along the lateral line trunk canal, and a minute sensor enveloped in a gelatinous cupula, referred to as a neuromast, is located between each pair of pores. Drag forces resulting from fluid motions induced inside the LLTC by pressure fluctuations in the external flow stimulate the neuromasts. A two-level numerical model was developed that couples the vortical flow outside the lateral line trunk canal to the flow stimulating the neuromasts within it. The results suggested that, for the conditions explored, the lateral line trunk canal acts as a low-pass filter with respect to the external flow oscillating pressure gradient. These fluid mechanic results were in general agreement with corresponding physical and electrophysiological observations made by various biologists.
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  Superhydrophobic Surfaces
  Superhydrophobic surfaces such as the lotus leaves are extremely difficult to wet. The contact angle of water droplets on such surfaces exceeds 150°. Examples of potential applications are: self-cleaning fabric, microfluidic device, and hydrodynamic drag reduction. To estimate the droplet contact angle on such surfaces, Surface Evolver) was used to compute the droplet shape on micropatterned surfaces (see figure on the left).
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  Flow in a Hard Disk Drive
  With increases in the recording density and rotation speed of hard disk drives, the aerodynamic aspect of drive operation now has a significant impact on the design of storage systems. The increasing areal density requires improving the positioning accuracy of the magnetic head whereas the increasing rotational disk speed generates a strong unstable air flow inside the drive, causing vibrations of the disks and the suspensions/magnetic heads. These vibrations, especially for the suspensions, have a considerable effect on head positioning accuracy that can result in read/write failure of the drive. In order to have a better understanding of the aerodynamics phenomena in a hard disk drive, a simplified but realistic device was built to investigate the airflow experimentally. A numerical approach was proposed and tested to compute the airflow around the suspensions and estimate the aerodynamic forces acting on them.
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  rotor-stator interactions in a turbomachinery centrifugal compressor
  Rotor-stator interactions in a centrifugal compressor typicallo found in helicopters were investigated numerically. Unsteady 2.5D calculations were performed with the code Colibri (ONERA), and compared with Laser Doppler Velocimetry and pressure measurements performed at ONERA on a test bench Pi4. It was found that Colibri could be a powerful tool to assess the acoustic noise generated by rotor-stator interactions.