Concept and evaluation of bay health:the role of numerical model in the Yueqing Bay,China

To better evaluate the three-dimensional bay health and predict the dynamic bay health conditions, a concept of numerical bay health was introduced and a method of numerical bay health evaluation（NBHE） was developed.To support the NBHE method, a numerical bay health index（NBHI） system was constructed, which assess the natural and socio-economic effects on the entire bay. Five index groups are combined to formulate the NBHI,including geometry, hydrodynamics and sediment dynamics, bio-ecology, water quality and socio-economy.Each group has different number of indices selected and weighted using AHP method according to their importance. Data were mainly synthesized from a variety of numerical models together with monitoring programs, which provide superior to other approaches in discriminating data integrity and predicting data in future. The NBHE method using NBHI system was applied in the Yueqing Bay during spring tide in April 2007.According to the NBHE results, Sta. A, at the surface level of the estuarine mouth, has a healthy geometry condition, sub-healthy hydrodynamic and sediment dynamic condition, and unhealthy water quality and bioecology conditions. The integrated healthy score at Sta. A indicates its sub-healthy condition.

A NEW NUMERICAL MODEL FOR THREE DIMENSIONAL SURFACE WATER FLOWS

A three dimensional numerical model based on the Reynolds equations is presented that can be used to predict the surface water flow in open channels.The model uses a computational mesh that conforms to the free water sur- face and the bottom of the channel so that the accuracy of boundary condition application,code complexity,and e- conomy could be enhanced.The k-ε turbulence model is used to estimate the eddy viscosity coefficient.Instead of using the“rigid-lid”approximation a 2-D equation derived from integrating the continuity equation over the total depth is adopted to determine the elevation of the free water surface.A new algorithm is presented based on the conventional SIMPLE procedure.The block correction technique is employed to enhance rate of convergence. The model presented is applied to a bottom discharge into a rectangular straight channel for three dimensional phenomena to obtain the free water surface configuration,velocities and pressure.The computed results are in good agreement with the previous experimental values.

Experimental and numerical research on squat silo and large size horizontal warehouse during quasi-steady-state storage

Traditional method to prevent stored grain from deterioration is to control grain temperature.A three dimensional(3-D)numerical model was established to study the temperature variation in outdoor squat silo and large size horizontal warehouse at quasi-steady-state.In this research,porous media model and solar radiation model were adopted.Numerical and experimental results showed that grain temperature was influenced by temperature of wall,height of grain and the distance between grain and the wall.Temperature changes dramatically at the top layer of grain heap due to solar radiation and heat convection at air layer.Temperature of grain close to wall increased with the increasing of ambient temperature.The model established in this research is suitable for predicting grain temperature in outdoor squat silo and large size horizontal warehouse.