Jinil Park

Actuation and control of a turbulent channel flow using Lorentz forces

Results concerning the design and fabrication of electromagnetic actuators, and their application to affect the wall shear stress in a fully turbulent channel flow are discussed. The actuators utilize a Lorentz force to induce fluid motion due to the interaction between a magnetic field and a current density. The actuators are comprised of spanwise-aligned rows of permanent magnets interlaced with surface-mounted electrodes, segmented to allow the Lorentz force to be propagated in the spanwise direction. Problems commonly associated with electromagnetic flow control—electrolysis, bubble formation, and electrode corrosion are substantially reduced, and in most cases eliminated by the use of a conductive polymer coating. The actuators generate velocity profiles with a penetration depth into the flow of approximately 1 mm (set by the electrode/magnet pitch) and maximum velocities of approximately 4 cm/s. The actuation velocities are found to scale linearly with forcing voltage and frequency. The electrical t...

Active control of flow over a sphere for drag reduction at a subcritical Reynolds number

Active control of flow over a sphere at

DRAG REDUCTION IN TURBULENT FLOWS USING LORENTZ FORCE ACTUATION

\hbox{\it Re}\,{=}\,10^5

Near-Surface Velocimetry Using Evanescent Wave Illumination

, based on the free-stream velocity

Fabrication and Performance Investigation of Surface Temperature Sensor Using Fluorescent Nanoporous Thin Film II

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The influence of noise in vehicles on the driver’s subjective evaluation of driveability:

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Modification of Turbulent Boundary Layer Flow by Local Wall Vibration

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Near-surface velocimetry using evanescent wave illumination

, is carried out for drag reduction using a time-periodic blowing and suction from a slit on the sphere surface. The forcing frequency range considered is one to thirty times the natural vortex-shedding frequency. With the forcing, the drag on the sphere significantly decreases by nearly 50% for the forcing frequencies larger than a critical frequency (about

Particle image velocimetry experiments on a macro-scale model for bacterial flagellar bundling

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Bimetallic phenylene-bridged Cp/amide titanium complexes and their olefin polymerization

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