Wave diffraction of two concentric porous cylinders with varying porosity was studied by using an analytical method based on eigenfunction matching.The fluid domain around the cylinders is divided into three sub-domai...Wave diffraction of two concentric porous cylinders with varying porosity was studied by using an analytical method based on eigenfunction matching.The fluid domain around the cylinders is divided into three sub-domains and in each sub-domain an eigenfunction expansion of the velocity potential is obtained by satisfying the Laplace equation,the boundary conditions on the free surface and on the sea bed.The unknown coefficients of eigenfunction expansions are determined by boundary conditions on the porous hulls.In the paper,the boundary conditions are based upon the assumption that the flow in the porous medium is governed by Darcy's law.Two porous-effect parameters applied on two porous cylinders are functions of the vertical coordinate instead of the constant.Wave loading on the outer and inner cylinder is presented in the numerical results.展开更多
The vertical distribution of an emergent vegetation in wetlands and marshes is generally non-uniform due to the variations of the stem thickness and the leaf density.This study focuses on the effect of the varying ver...The vertical distribution of an emergent vegetation in wetlands and marshes is generally non-uniform due to the variations of the stem thickness and the leaf density.This study focuses on the effect of the varying vertical porosity on the hydrodynamic characteristics of the emergent vegetation flow.The new governing equation for the emergent vegetation flow with varying vertical porosity is established by applying the poroelastic media flow theory.According to the movement mechanism of the water flow in the porous media and the experimental data,the best fitted expression of the permeability is established for the emergent vegetation flow.The velocity distribution is obtained with the finite analytic method.Then,a flume experiment is performed using truncated cones to simulate the actual vegetation with varying vertical porosity.The calculated velocity distribution is compared with the measured data,which shows that the theoretical results are in good agreement with the experimental data.Finally,the influence of the vertical porosity distribution on the vegetation flow characteristics is analyzed graphically.The study can provide a useful reference and technical support for further study of the flow with a complex shape vegetation.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.51079032
文摘Wave diffraction of two concentric porous cylinders with varying porosity was studied by using an analytical method based on eigenfunction matching.The fluid domain around the cylinders is divided into three sub-domains and in each sub-domain an eigenfunction expansion of the velocity potential is obtained by satisfying the Laplace equation,the boundary conditions on the free surface and on the sea bed.The unknown coefficients of eigenfunction expansions are determined by boundary conditions on the porous hulls.In the paper,the boundary conditions are based upon the assumption that the flow in the porous medium is governed by Darcy's law.Two porous-effect parameters applied on two porous cylinders are functions of the vertical coordinate instead of the constant.Wave loading on the outer and inner cylinder is presented in the numerical results.
基金Project supported by the National Natural Science Foundation of China(Grant No.51479145).
文摘The vertical distribution of an emergent vegetation in wetlands and marshes is generally non-uniform due to the variations of the stem thickness and the leaf density.This study focuses on the effect of the varying vertical porosity on the hydrodynamic characteristics of the emergent vegetation flow.The new governing equation for the emergent vegetation flow with varying vertical porosity is established by applying the poroelastic media flow theory.According to the movement mechanism of the water flow in the porous media and the experimental data,the best fitted expression of the permeability is established for the emergent vegetation flow.The velocity distribution is obtained with the finite analytic method.Then,a flume experiment is performed using truncated cones to simulate the actual vegetation with varying vertical porosity.The calculated velocity distribution is compared with the measured data,which shows that the theoretical results are in good agreement with the experimental data.Finally,the influence of the vertical porosity distribution on the vegetation flow characteristics is analyzed graphically.The study can provide a useful reference and technical support for further study of the flow with a complex shape vegetation.
