Self-propulsion of small bubbles and droplets through the action of surface-tension gradients is relevant to important processes in both nature and technology, ranging from Marangoni propulsion of microorganisms to transport in microfluidic devices. Here, we use high-fidelity simulations to characterize the fluid dynamical and interfacial phenomena underlying the spontaneous self-propulsion of a small bubble approaching a solid surface. The spreading of surface active contamination at the front of the bubble creates the surface-tension gradient which propels the bubble forward through the Marangoni effect. Results for finite Reynolds numbers and a deformable bubble show that the impact of the active bubble with the solid surface generates fluid stresses that may contribute to the cleaning of fouled surfaces. This effect, however, depends strongly on the initial separation between the bubble and the solid surface.

通过表面张力梯度的作用自推进小气泡和液滴与自然界和技术中的重要过程相关，从微生物的 Marangoni 推进到微流体装置中的传输。在这里，我们使用高保真模拟来描述小气泡接近固体表面的自发自推进背后的流体动力学和界面现象。表面活性污染物在气泡前部的扩散产生表面张力梯度，通过马兰戈尼效应推动气泡向前。有限雷诺数和可变形气泡的结果表明，活性气泡对固体表面的影响会产生流体应力，这可能有助于清洁污染表面。然而，这种影响