The separation point of the flow around a circular cylinder has been numerically and experimentally investigated in the regime of Reynolds number less than 280. The present results reveal that the long-existing discrepancy in the data concerning the time-averaged separation angles reported in the literature results mainly from the oscillating characteristics of the flow separation on the cylinder surface and the experimental methodologies rather than the commonly mentioned blockage-ratio effect. In the present experiment, the time-averaged separation angles are obtained by averaging the instantaneous images from a soap-film flow visualization instead of from the commonly used streakline images from finite time exposures. Excellent agreement has been achieved between the present experimental results and numerical simulations by the spectral element method. Particle-streak visualization in a towing tank has also been conducted to compare with that of the two-dimensional soap-film experiments. It reveals that the separation angle is insensitive to the three-dimensional effect. Variations of the time-averaged separation angles with Reynolds number can be represented by a four-term θ s -Re −1/2 relationship in the range of 7 6 Re 6 200. Moreover, if the data in the very low Reynolds number region are excluded, a simple linear θ s -Re −1/2 relationship can be derived for 10 6 Re 6 200. Since the dimensionless boundary layer thickness and the Strouhal-Reynolds number relationship for the circular cylinder are also known to be proportional to Re −1/2 , this linear relationship offers direct evidence that the flow characteristics of the boundary layer extend downstream along the cylinder surface to the separation point in this Re-range. The blockage effect on the separation angle has also been quantitatively analysed.

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Wake characteristics of flow over a heated circular cylinder in the three-dimensional transitional wake regimes are studied using smoke wire flow visualizations and hot-wire anemometry techniques. The onset of wake from laminar vortex shedding to transition is found to be delayed by heating of the cylinder and the transitional wakes still developed at higher Reynolds numbers. As the cylinder is heated, vortex shedding frequencies are reduced throughout the Reynolds number range and discontinuities in St-Re relationships are typical in all temperature ratios studied. Critical Reynolds numbers for all transitional wake regimes increase linearly with increasing temperature ratios. Criteria for measuring the onset of transition for flow around a heated cylinder are proposed. Excellent agreement in Strouhal-effective Reynolds number relationships for the heated and unheated cylinders validates the applicability of the effective Reynolds number concept in both laminar and transitional wake regimes ͑47Ͻ ReϽ 400͒.

In this paper, an integrated multifunctional biochip detection system, which we call "OBMorph", are presented. This unique system integrates several optoelectronic-based biological diagnostic tools such as an ellipsometer, a laser Doppler vibrometer/interferometer, a SPR (surface plasmon resonance) analyzer, an interference microscope, a photon tunneling microscope, an optical coherence tomography unit and a confocal scanning microscope. This OBMorph system, useful as a powerful optical metrology diagnostic tool, can be used at the beginning of sensor chip fabrication, on to signal detecting and monitoring, and to the final biological analysis. The principles and experimental results of this multifunctional biochip detection OBMorph system are presented.In addition, an innovative SARS (Severe Acute Respiratory Syndrome) virus denaturing chemical compound that was derived using the OBMorph system to study biolinker fabrication in biochips, are discussed. Several testing strategies are presented herein which proves the effectiveness of the new chemical compound, biochip technology in denaturing the SARS virus. Analysis under an atomic force microscope confirms the actual breaking down of the virus treated by the chemical compound. The fundamentals of how the chemical compound denatures the virus and renders it toxicity useless, is based on principles of nanotechnology and bio-mechanics. Results from preliminary studies show that this denaturing principle can be also effective against other deadly viruses and even bacteria. Some design strategies and innovative working mechanisms derived from study of this chemical compound which can denature the SARS-CoV, are also discussed.