Numerical Simulation On The Wave Tank And Spatial Development Of Disturbance In Plane Poiseuille Flow

For the global biogeochemical cycles, gas exchange is one important linkbetween the atmosphere and the ocean. Thus, in Recently, the gas exchange betweenthe atmosphere and the ocean has received much attention. Air-water gas transfer isalso very important in other areas, such as environmental engineering and chemicalengineering. As the first step of studying the gas transfer on the interfacial surface, anumerical wave tank is built in this dissertation.In this numerical wave tank, the two-phase flow theory is firstly introduced tomodel the behavior of water and air. The interface is tracked by VOF method. Thewave is introduced by an oscillating plane and before the outlet boundary, a artificialdamping layer is presented to absorb the reflection wave. Thecontrol-volume-based technique is used to convert the governing equations toalgebraic equations that can be solved numerically. The non-uniform rectangle gridsare arranged according to requirements, such as finer grids at air-water interface.The outlet pressure condition is used at the top boundary. By comparing the theorywith wave profile and the time-depending pressure and velocity at a certain point,the correctness of our numerical wave tank is proved. Numerical results show theabsorb intensity is mainly depend on the amplitude and length of wave and the depthof water. The effects of the air pressure and air and water viscous on the water waveare studied. It is found that the above factors have little influence on water wave.The spatial development of disturbances in plane Poiseuille flow is simulatednumerically. The controlling equations are N-S equations. The mean velocity profileis at the inlet boundary and the outflow is used at the outlet boundary. ATollmien-schlichting (TS) wave with small amplitude known from Orr-Sommerfeldequation is superimposed on the mean flow field to introduce a small disturbance.Numerical results show that the spatial development of disturbance is in a goodagreement with that of Orr-Sommerfeld equation.