Lattice Boltzmann Simulation Of Two-Phase Droplet Dynamics Passing Through Obstacles

In order to optimize the structure of the metal foam reactor, which is a equipment for the biodiesel synthesis with high-efficiency, the dynamics of the droplet flowing through the obstacle and metal foam was simulated using lattice Boltzmann method. There is violent deformation around the interface due to the complex structure of the metal foam. Based on the topic, the main research contents and conclusions are listed as follows:(1) In order to verify the accuracy of LBM algorithm, Poiseuille flow and the flow over a cylinder were simulated. Thereinto, Shan-Chen model was used to simulate the relaxation of the square droplet, to test Laplace’s law and to investigate the evaluation of contact angle. In addition, the correction of Shan-Chen model code was proved.(2) Dynamics of droplet passing a single obstacle was simulated. The droplet deformation is influenced by the shape and the eccentric ratio of obstacle. The coalescence length Lr of broken droplets is related to the size and the shape of obstacle and Reynolds number Re. Lr shows a logarithmic increase with the increment of Re. There exists a critical Re, beyond which Lr of big obstacle becomes shorter than that of the smaller obstacle.(3) Dynamics of droplet passing two parallel obstacles was investigated. It was found that high velocity generates wider critical inserting width hr. Bigger sized droplet and smaller sized obstacle both generate wider hr. The effect of the obstacle’s shape on hr is not obvious.(4) Dynamics of droplet flowing through the metal foam was studied. Compared with the obstacle, metal foam is more favorable to the generation of smaller droplets. Big PPI is more favorable to the formation of small droplets. However, the pressure drop of bigger PPI is higher than that of smaller PPI. So the choice of PPI should be reasonable.