Marangoni flow

Mechanism

In simple cases, the speed of the flow ${\displaystyle u\approx \Delta \gamma /\mu }$, where ${\displaystyle \Delta \gamma }$ is the difference in surface tension and ${\displaystyle \mu }$ is the viscosity of the liquid. Water at room temperature has a surface tension of around 0.07 N/m and a viscosity of approximately 10 Pa⋅s. So even variations of a few percent in the surface tension of water can generate Marangoni flows of almost 1 m/s. Thus Marangoni flows are common and easily observed.