浸渍涂覆过程中液膜流动的数值模拟

Numerical Simulation of Liquid Film Flow in Dip Coating Process

结合有限元法和网格重划分法,在毛细数(Ca)0.01<Ca<20范围内对硅油流体浸渍涂覆过程中的薄膜流动问题进行模拟,并将牛顿流体膜厚的模拟结果与其他文献中实验结果进行比较;通过对不同流体薄膜流动问题的分析,讨论了流体流变性能和加工参数对涂覆膜厚和自由面的影响规律。对流动过程中流场的分析表明:当流场稳定后,基板邻近的流体沿基板向上运动,而其他的流体流回槽中,在其内部形成一个漩涡,当流体黏度较小时,在自由面上形成一个驻点,而当黏度较大时驻点在内部形成;随提拉速度增大,几种流体的驻点均远离基板,同时非牛顿流体内部的漩涡逐渐减小。

Finite element method（FEM）was combined with remeshing method to simulate the film flow problem in dip coating for silicone oil fluids in the range of capillary numbers 0.01Ca20,and the simulation result of Newtonian fluid film thickness was compared with the experimental results in other articles.The film flow problems for different fluids were analyzed to illustrate the effects of the rheological properties and processing parameters on the film thickness and the free surface.The analysis of the flow field shows that the fluid near the substrate moves upward along the substrate when the low field is stable,while other fluids return into the groove and form a vortex;a stagnation point is formed on the free surface when the fluid viscosity is relatively small,while the stagnation point is formed in the flow field when the fluid viscosity is relatively large;and the stagnation points of several fluids move away from the substrate with the rise in withdrawal speed.Simultaneously,the vortex in non-Newtonian fluid decreases gradually with the rise in withdrawal speed.