2023 年 37 巻 1 号 p. 46-54
A microbubble generated by the laser beam’s photothermal conversion induces convective flow by the Marangoni effect at the gas-liquid interface. This flow is useful for the transport and accumulation of nanoparticles in liquid. This study investigates the regime of the convective flow in nanoparticle suspension around the generated microbubble. The empirically observed flow regime was initially similar to that of theoretically predicted convection in pure water, which has a circulating flow driving particles 100 μm away from the microbubble. However, after 10 ms of the laser heating, the size of the circulating flow decreased to the same as the bubble diameter. Additionally, a numerical simulation also shows that the decreasing of the circulating flow is observed when the driving force at the interface is limited to the shear stress of > 140 N/m2.
