Dynamic interfacial tension gradient, local

Capillarity phenomena are everyday occurrences that result from the existence of surface tension or interfacial tensions. In addition to the static phenomena discussed herein, surface tension and capillarity are also responsible for numerous dynamic phenomena that may result from localized gradients in temperatures or in compositions the study of dynamic capillary phenomena (e.g., Marangoni flows, Benard cells) is the subject of much literature coverage and is beyond the scope of this survey. 

In the course of interfacial mass transfer, from molecular point of view, the process is stochastic, that means some local molecules may undergo the mass transfer in advance than the others, so that small concentration gradient (where i — x, y, z) is established at the interface. As the surface tension a is function of concentration, it follows that the surface tension gradient is also created at the interface. If is increased up to a critical point, the fluid dynamic instability will appear to induce the interfacial convection as well as the formation of orderly structure at the interface. At the same time, the rate of mass transfer may be enhanced or suppressed depending on the properties of the mass transfer system concerned such phenomena is generally regarded as interfacial effect. 

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