A Numerical Simulation On Motion Of A Bubble On A Downward Facing Circular Wall

The fluid motion in complex flow field is widely seen in industrial, energy and environment areas, In the field of computational fluid dynamics having attracted the attention of scholars in the field of computational fluid dynamics. Previous studies on the complex flows, mostly confined to the Cartesian coordinate system, which leads to description of complex boundary is not accurate. Therefore study the complex flows based on body-fitted coordinate systems has great realistic significance.In order to study the single-phase flow field with complicated boundary, lattice Boltzmann method (LBM) and generalized form of interpolation lattice Boltzmann method (GILBM) are applied to study the inclined cavity with a tilt angle of45°lid-driven flow and fluid flow characteristics in Roach channel. In terms of fluid flow in the Roach channel, GILBM has higher computational efficiency than LBM with the same grid resolution. By analyzing the boundary vorticity and boundary pressure, LBM’s accuracy fall behind GILBM. The inclined cavity with a tilt angle of45°lid-driven flow is simulated as the Reynolds number equal to100and1000respectively. It is found out that when the Reynolds number is small, the results obtained from the two methods are in good agreement with the benchmark solution. As the Reynolds number increases to1000, the accuracy of simulation based on GILBM is superior to LBM regardless of the velocity distribution or the location of the vortex center. Using GILBM method to the inclined cavity with a tilt angle of30°lid-driven flow and the flow around a circular cylinder. Comparing the calculated results with the literature results, Verified the GILBM method’s accuracy and feasibility when the grid is higher irregular. According to the different requirements of the complexity of the boundary shape, meshing and accuracy, the two methods have some advantages and disadvantages respectively.In addition, this paper try to combine the body-fitted coordinate with two-phase flow model of LBM, and to design program. Laplace law, the single bubble rising and translational flow field in inclined cavity confirmed the feasibility of the method and the accuracy of the program. This method is applied to simulate bubble sliding process along curved surface. Through analysis of calculation results, the following conclusions were obtained:during bubble sliding process along curved surface, bubble deformates largely at the begaining. As the bubble reach a certain location, it will get rid of the shackles of the wall, and moves to the flow field freely. To further examine the law of bubble motion, the bubble velocity curves are also given, due to the influence coming from the wall, the bubble velocity fluctuations during movement.In this paper, the simulation results show that GILBM is accurate to calculate single-phase complex flow, and two-phase flow model of LBM in body-fitted coordinate is feasible to calculate the complex channel. But this model is still relatively rough, still need further improvement.