用格子Boltzmann方法模拟弹性哑铃在牛顿流体中的运动

利用格子Boltzmann方法分别模拟了在同等初始条件下释放的单个带电和不带电弹性哑铃在牛顿流体中的运动．模拟所得的数值结果表明，对于单个不带电的弹性哑铃，当其被置于质心偏离管道中心线的初始位移处水平地释放后，弹性哑铃逐渐向管道的中心线漂移，当其质心漂移到达管道中心线后，弹性哑铃呈现稳定的垂直下落状态，在沉降运动中，弹性哑铃的方向保持水平方向不变．对于同等初始条件下释放的单个带电弹性哑铃，当流体的介电常数小于管道壁的介电常数时，由于静电极化的作用，弹性哑铃在其沉降过程中将受到管道壁的吸引力，该力使得弹性哑铃的运动发生显著的改变，以至于它处于最终垂直下落状态时，其质心尚未到达管道的中心线．

LATTICE BOLTZMANN SIMULATION OF THE SEDIMENTATION OF A SINGLE ELASTIC DUMBBELL IN A NEWTONIAN FLUID

Based on the lattice Boltzmann method (LBM),the sedimentations of a single charged and un-charged elastic dumbbell in a Newtonian fluid under the same initial conditions have been simulated.All of the numerical results show that,for the un-charged elastic dumbbell,it drifts towards to the centerline of the tube with its sedimentating after released at the initial X_0=0.3 L position horizontally,finally fall down vertically and steadily when its centroid reaches at the centerline of the tube,and the orientation of the un-charged elastic dumbbell remains horizontally during the whole sedimentation.For the single charged elastic dumbbell released at the same initial conditions,there is a Coulomb force exerted on it during the sedimentation due to the polarizing effects,which change its horizontal translation and rotation significantly.When the dielectric constant of the liquid is samller than that of the wall,the direction of the Coulomb force is opposite to that of the hydrodynamic force.Therefore there is a critical linear charge denisty q_c,at which the elastic dumbbell will fall vertically with its centroid off centerline.