Bubbles Rise In The Vertical Flow Channel Flow And Heat And Mass Transfer Numerical Simulation

The motion of gas bubbles in the liquid has been found in wide engineering applications. To simulate the bubbles' motion, the most important is the development of the interface tracking technique which is widely used in the engineering fields, such as power, energy resources, machine and water conservancy. Therefore, the simulation of the bubbles' motion has been considering as a challenge and key work in two-phases computational fluid dynamics (CFD).In this thesis, the first work is to do a comparison of three kinds of interface reconstruction methods which are applied to the volume of fluid (VOF) method. They have been carried out on the numerical simulation in the removing field, the rotating field and the sheared field. It is clearly seen that although the PLIC method has smeared the sharp part of the interface a little bit, it gets the most sharp and accurate interface in the three methods, while the FLAIR method is much better than Hirt and Nichols' s method.Based on the first work, the PLIC method is chosen to simulate a single bubble' s motion in the column. A tension model, called CSF, is employed to dispose the surface tension. The governing equations are solved using a finite volume method on a body-fitted mesh. Using central differencing and upwind schemes to discrete the diffusion terms and convection terms in the governing equations, respectively. The coupling between pressure and velocity problem has been solved by SIMPLE algorithm.It can be found, when Eo=56. 3, M=0. 8, Re=8. 6, with the time passing the bubble becomes ellipse from sphere, and re-circling area rear of the bubble increases until the field become steady. It influences the distribution of the temperature in the column, in particular for a district rear of the bubble. In conditions of the same time, the same size of the bubbles, the district become smaller when only reducing the column' s diameter, and the influence on the temperature become larger in the up-stream, little in the down-stream.The conclusions of the thesis can be referenced in theory for deep and further research.