Zhou Zexuan
Email Address
tmszz@nus.edu.sg
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Publication Numerical simulation of sediment transport near sea bed under waves* * Project supported by Defense Science and Technology Agency, Singapore (Grant Nos: R-264-000-127-112 and R-347-000-021-422).(2006-07) ZHOU, Z.-x.; LIN, P.-z.; CIVIL ENGINEERING; TROPICAL MARINE SCIENCE INSTITUTEThe sediment transport near sea bed under waves is simulated using a three-dimensional (3D) numerical model that solves Navier-Stokes equations for incompressible flow, the sediment transport equation and the bed morphology equation. The numerical model consists of two basic modules, the 3D hydrodynamic module (HD) and sediment transport module (ST). The sigma-coordinate is used to convert the wavy flow-field into a cube leading to the easier realization of flow-field and boundary conditions. The model is able to simulate the dynamic change of suspended sediment concentration and bed morphology under various flow conditions. The case where the initial flow-field is full of evenly distributed suspended sediment subjected to a linear wave train is simulated. The results on sediment concentration distributions in the horizontal and vertical directions and resulting bed morphology are verified by the analytical solutions developed in this study. The good agreements between the numerical and analytical results show that the present numerical model is reliable in predicting sediment transport in coastal areas under waves. © 2006 Publishing House for Journal of Hydrodynamics.Publication Cumulative distributions of rainfall rate and microwave attenuation in Singapore's tropical region(2000-05) Zhou, Z.X.; Li, L.W.; Yeo, T.S.; Leong, M.S.; ELECTRICAL ENGINEERINGThe microwave attenuation due to rainfall in tropical regions has not been very widely studied yet. In Singapore's tropical environment, line-of-sight microwave communication links were set up and have been operated for several years to study the microwave attenuation characteristics due to tropical rainfall. In this paper the experimental results are presented, including the cumulative distributions of rainfall rate, the cumulative distributions of microwave attenuation, the relationship between specific attenuation and rainfall rate, and frequency scaling formulae. The results show that the rainfall rate and the microwave propagation characteristics in Singapore over a 10-month experiment period are out of accord with International Radio Consultative Committee predictions.Publication Analysis of experimental results on microwave propagation in Singapore's tropical rainfall environment(1999-06-20) Zhou, Z.X.; Li, L.W.; Yeo, T.S.; Leong, M.S.; ELECTRICAL ENGINEERINGThe attenuation due to rainfall in tropical regions has generated more concern in recent years. In Singapore, a microwave propagation experiment of line-of-sight communication has been conducted, and some experimental results have been obtained. The specific rainfall attenuation and rain attenuation duration temporal cumulative distributions over a ten-month period for 15 and 38.6 GHz are analyzed in this paper. The frequency scaling relationship between distributions is also discussed in detail. The results obtained in Singapore's tropical environment are found to be quite different from the CCIR's predictions. The results of our experiment can be employed to guide the design and application of terrestrial microwave communication systems, especially in tropical regions.