沿多孔壁面流动的液膜线性稳定性分析

针对沿多孔壁面流动的牛顿流体液膜进行线性稳定性分析，特别考虑中等雷诺数的情形。认为多孔壁面处的流动满足Beavers-Joseph滑移边界条件，采用动量积分方法，得到色散关系和中性稳定曲线。多孔壁面的渗透性促进了液膜流动的不稳定，加快了液膜表面波的移动。随着雷诺数增大，中等雷诺数范围的最大增长率呈现先增大后减小趋势。最大增长率极值和不稳定波数区域与壁面渗透性有关。通过能量分析探究多孔介质渗透性对流动稳定性的作用机理，多孔壁面滑移速度的存在使得平均流速增大，速度梯度减小，导致黏性耗散减小从而促进流动失稳。

Linear stability analysis of liquid films flowing down a porous wall

The paper conducted a linear stability analysis on the Newtonian liquid films flowing down a porous wall,especially concerning about the case of moderate Reynolds number.It was considered that the flow at the porous wall satisfied the Beavers-Joseph slip boundary condition.And the momentum integral meth-od was used to obtain the dispersion relation and the neutral stability condition.The results show that the per-meability of porous wall promotes the instability of liquid film flow and accelerates the movement of liquid film surface fluctuation.With the increase of the Reynolds number,the maximum growth rate increases first and then decreases in the range of moderate Reynolds number.The extremum values and cutoff wave number of growth rate were related to the wall permeability.The mechanism of porous media permeability affecting the stability has been discussed by energy analysis.It is considered that the existence of porous wall slip velocity increases the average flow velocity and decreases the velocity gradient,which leads to the decrease of viscous dissipation and the reinforcement of flow instability.