The flow and thermal characteristics of the Marangoni convection (thermocapillary flow) around a microbubble are described in this study for the case in which a bubble is attached to a locally heated microchannel wall (hot spot applied). By providing a heat source near the bubble and generating a temperature gradient on the surface of the bubble, Marangoni convection can be produced in the surrounding fluid. In the microscale, this effect is significant, and strong vortices and streaming flow can be formed in the channel. We investigate the effects of the location of the hot spot on the temperature field and vortex structure based on numerical simulations. A circulating flow is generated when the hot spot is located at the center of the bubble, while a pair of strong vortices appears when the hot spot is located away from the center of the bubble. Further, we evaluate the effect of heat conduction and temperature dependence of the fluid viscosity on the temperature field and the resulting Marangoni convection. To compare the present results with the experimentally measured ones and to visualize the flow using particles, we solve the equations governing the motion of the particles and evaluate the contribution of each force term. The results show that the trajectory of the particle follows the streamline, but can deviate to a certain degree at the location where the streamline curvature is large.

中文翻译：

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围绕局部加热的通道壁的微气泡周围的MARANGONI对流

在此研究中，描述了气泡附着在局部加热的微通道壁（施加热点）的情况下，微气泡周围的Marangoni对流（热毛细流动）的流动和热特性。通过在气泡附近提供热源并在气泡表面上产生温度梯度，可以在周围的流体中产生马兰戈尼对流。在微尺度上，这种影响是显着的，并且可以在通道中形成强烈的涡流和流动。基于数值模拟，我们研究了热点位置对温度场和涡旋结构的影响。当热点位于气泡中心时会产生循环流，而当热点远离气泡中心时会出现一对强涡旋。此外，我们评估了导热和流体粘度与温度的关系对温度场以及由此产生的Marangoni对流的影响。为了将当前结果与实验测量的结果进行比较并使用颗粒可视化流动，我们求解了控制颗粒运动的方程式，并评估了每个力项的作用。结果表明，粒子的轨迹遵循流线，但在流线曲率较大的位置会有所偏离。我们求解控制粒子运动的方程式，并评估每个力项的贡献。结果表明，粒子的轨迹遵循流线，但在流线曲率较大的位置会有所偏离。我们求解控制粒子运动的方程式，并评估每个力项的贡献。结果表明，粒子的轨迹遵循流线，但在流线曲率较大的位置会有所偏离。