悬浮液中纤维的运动和旋转行为在许多现代工业领域都非常重要.Jeffery解析得到了牛顿流中椭球型纤维的动力学演化方程,但方程只有在平面简单剪切和拉伸流的条件下才有解析解.采用数值求解时,由于方程中cotθ的存在会出现奇异性.采用随体坐标的方法,消除了方程的奇异性,算法的有效性通过与解析解的比较得到了验证,并为复杂流场下纤维的动力学数值计算提供了一个可行的方法.
The translational and rotational dynamics of fibers suspended in a fluid medium are important in many different fields of modem technology. Jeffery derived an equation of motion for a single rigid ellipsoidal particle suspended in Newtonian fluids. Unfortunately, the analytical solutions of Jeffery equation could only be obtained in a simple planar shear flow and a planar elongational flow. The main difficulty in the numerical treatment of Jeffery equation is the singularity due to the term cot θ. In this paper, a co-rotational coordinate system is proposed, which can completely eliminates this singularity. The validity of the proposed scheme is shown by a comparison between numerical results and the analytical solution. New algorithm can easily be extended to simulate the dynamics of single fiber in complex flow fields.