Even though the mechanical heart valve (MHV) has been used routinely in clinical practice for over 60 years, the occurrence of serious complications such as blood clotting remains to be elucidated. This paper reviews the progress that has been made over the years in terms of numerical simulation method and the contribution of abnormal flow toward blood clotting from MHVs in the aortic position. It is believed that this review would likely be of interest to some readers in various disciplines, such as engineers, scientists, mathematicians and surgeons, to understand the phenomenon of blood clotting in MHVs through computational fluid dynamics.

Installation of H-type vertical axis wind turbines is in many cases limited by the inherent start-up issues associated with this type of turbine. This could be crucial in environments with low wind speed. The aim of this study is to provide an appropriate CFD modeling setup for investigation of the start-up behavior associated with this class of turbines. For this purpose, a series of transient CFD simulations were carried out using ANSYS Fluent. In contrast with the conventional approach, whereby a constant angular velocity is specified for the rotor, in the present work, the turbine was left free to accelerate based on the torque experienced over time. Careful considerations were made regarding turbulence modeling and grid generation, which are key to ensuring accuracy in this investigation. The result of this simulation, in the form of an accelerating time series, demonstrates good agreement with the published experimental data, and the method yields a high level of accuracy, proving its usefulness for similar problems. In another attempt, the validated CFD setup was utilized to evaluate the effects of several geometric attributes of the turbine rotor on the starting characteristics. Symmetric and cambered airfoils of different thicknesses with a wide range of pitch angles were examined. The optimum start-up characteristics were observed with the use of a medium-thickness cambered airfoil, NACA2418, put to use with an outward pitch angle of 1.5°; this configuration decreased the start-up time while retaining the turbine's peak performance.

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a b s t r a c tAn efficient analytical method for vibration analysis of a Euler-Bernoulli beam with Spring Loading at the Tip has been developed as a baseline for treating flexible beam attached to central-body space structure, followed by the development of MATLABÓ finite element method computational routine. Extension of this work is carried out for the generic problem of Active Vibration Suppression of a cantilevered Euler-Bernoulli beam with piezoelectric sensor and actuator attached as appropriate along the beam. Such generic example can be further extended for tackling light-weight structures in space applications, such as antennas, robot's arms and solar panels. For comparative study, three generic configurations of the combined beam and piezoelectric elements are solved. The equation of motion of the beam is expressed using Hamilton's principle, and the baseline problem is solved using Galerkin based finite element method. The robustness of the approach is assessed.

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