The process of droplets jumping, against adhesive forces, from a solid surface upon coalescence has been studied in detail using experimentally-validated CFD modelling. Both Lattice Boltzmann and Volume of Fluid methods have been used to evaluate different kinematic conditions of coalescence inducing a jump velocity. Design of experiment techniques were used to establish near-optimal initial process parameters around which to focus the study. This multidisciplinary approach allows us to evaluate the jumping phenomenon for super-hydrophobic surfaces for which several input parameters may be varied, so as to improve the heat transfer exchange rate on the surface during condensation. Reliable conditions were found to occur for droplets within initial radius range of r=20-40 μm and static contact angle θs~160º. Moreover, the jumping phenomenon was observed for droplets with initial radius of up to 500 μm. Our study also shows that a critical contact angle for droplets to jump upon coalescence is θc~140º.
展开▼
机译：通过实验验证的CFD模型，已经研究了液滴在聚结时克服粘附力从固体表面跳出的过程，该过程已得到详细研究。 Lattice Boltzmann方法和Volume of Fluid方法都已用于评估聚结引起跳跃速度的不同运动学条件。实验技术的设计用于建立接近最佳的初始过程参数，以围绕该参数进行研究。这种多学科方法使我们能够评估超疏水表面的跳变现象，对于该表面，几个输入参数可能会发生变化，从而提高了冷凝过程中表面上的传热交换率。发现在初始半径范围r = 20-40μm和静态接触角θs〜160º范围内的液滴出现了可靠的条件。此外，对于初始半径最大为500μm的液滴观察到跳跃现象。我们的研究还表明，液滴聚结时跳跃的临界接触角为θc〜140º。
展开▼
