Lattice Boltzmann Simulation Of The Flow Over Vibrating Circular Cylinders

Lattice Boltzmann Method (LBM) based on mass and momentum conservations is used to simulate the complex fluid, in which the Continuity and the Navier-Stokes equations can be conformed, and which is a mesoscopic simulation method. Basing on LBM and D2Q9 model, and selecting the incompressible fluid with Re =200, this paper firstly studies the two-dimensional flow over a side-by-side vibrating circular cylinder pair (with four different spacing ratios T/D =1.2, 1.6, 2.2, 3.2). The calculated results indicate that the vibration of the cylinder pair has significant influence on wake patterns. When the amplitude and the frequency of the vibration are big enough, the vortex shedding can be locked up by the vibration. For each cylinder vibration frequency, there exists a threshold of vibration amplitude for the lock-on phenomenon. Secondly, we study the three-dimensional circular cantilever flow under Re =100 and using D3Q19 model. The amplitude and the frequency are still big enough. The results still show the significant influence on the wake from the vibration. Besides, the obvious three-dimensional effect, especially, the effect from free end of the cantilevered cylinder is displayed. Under these effects, the lock-on phenomenon isn't observed. We also did some experimental work. To compare with numerical results from a continuum model, the last part of our work is performing X-ray imaging experiments to study the flow-through drying of water-saturated porous media during gas injection. The results show that the liquid saturation profile and the rate of drying are dependent on the viscous pressure drop, the state of saturation of the gas and the capillary characteristics of the porous medium. During the injection of a completely saturated gas, drying occurs only due to gas expansion. Capillary-driven flows from regions of high saturation to regions of low saturation lead to more uniform saturation profiles. During the injection of a dry gas, a drying front develops at the inlet and propagates through the porous medium. A good agreement is found for the case of sandstone. The comparison is less satisfactory for the experiments with limestone.