Papers by Author: Xiao Lu Yan

Abstract: Saline intrusion is important for ecological reasons as well as water extraction purposes in estuaries. The distance of saline intrusion depends on a number of factors, including river discharge, tidal and wind mixing and gravitational circulation. In this paper, a simple and effective prediction model is derived for the saline intrusion at high slack water in a well mixed, funnel-shaped estuary whose cross-sectional area decreases exponentially (with convergence length a) with distance, x, inland. The model study shows that a graph of salinity against exp (x/a-1) is a straight line, with the slope proportional to the mixing coefficient Dx. The prediction model is presented and validated in Modaomen estuary, one of estuaries of Pearl River Delta in south China and the model results are compared, with good agreement, to the measured data. By analyzing the relationship between the salt intrusion length and tidal range, it is concluded that the optimal time of increasing runoff discharge to prevent saline intrusion is 2 to 3 days before neap tide.

Abstract: The porous media for liquid transporting and mechanical analysis, which are the hotspot studies in contaminant transport and machinery manufacturing, is hard to model in the computing simulation for the complexity of the media’s porosity. In the paper, an integrated approach is proposed to model the porous media with the framework of but not limited to sphere particles. Firstly, a series of particles are generated according to the grading curve in a closed box with the PFC3D, and then let the particles deposit freely for the gravity. After that the position and radium of each particle are exported to a file for import of AUTOCAD, where the particles are re-generated by the VBA script and the model for particles is constructed. The needed model is the porosity among the particles, so the model size is determined by a block and the model is gotten with the Boolean Operation which subtracts the particles from the block. And then with the different boundaries, the water transporting simulation in the porous media model is carried out with the Finite Volume Method (FVM). The results are proved reasonable by the previous studies.