为了深入理解热毛细对流不稳定性的特征,数值模拟了内环壁加热、外环壁被冷却的硅油环形浅液池内热毛细对流.发现在内外壁间温差相同的情况下,在内壁加热的液层里,流体表面的温度梯度高于外壁加热情况下10%左右;相应地,发生热流体波的临界Marangoni数Ma_c=3.06×10^5(或临界温差ΔTc=4.58K)低于外壁加热情况下的Ma_c=3.34×10^5(或ΔTc=5.0K).超过临界条件后,内壁加热液池内形成振荡的多涡胞热流体波,它由共存的两组波数相同、频率和振幅相同、沿周向传播方向相反、沿径向凹向高温壁传播的、弯曲螺旋状的热流体波组成,并相互干涉形成点状波纹.
In order to investigate the characteristics of thermocapillary flow instability, thermocapillary convection is investigated with three-dimensional numerical simulation in a shallow annular pool (depth d - 1 mm) of silicone oil (0.65 cSt, Pr = 6.7) with the heated inner wall and the cooled outer wall. The numerical results show that, surface temperature gradient in the pool heated from inner wall is 10% higher than that heated from outer wall with a fixed temperature difference between the outer and inner walls. Meanwhile, the critical Marangoni number for the incipience of hydrothermal wave (Mac = 3.06 ×10^5) in the pool heated from inner wall is smaller than that (Mac = 3.34×10^5) heated from outer wall. Furthermore, numerical results indicate the oscillatory multicellular wave in the pool heated from inner wall when Ma exceeds Mac. The oscillatory multicellular wave is composed of two hydrothermal waves propagating in opposite azimuthal directions, which are interfered each other to be dot ripple.