The features of the convective flows of multicomponent fluids in thin cavities

It is known that the specific hydrodynamic phenomena take place during the fluid motion through micro-channels. These effects can be observed only at a microscale level. However, the boundary between microfluidic effects and macroscopic hydrodynamic phenomena is indecipherable. It is quite difficult to predict a real behavior of hydrodynamic system in the case of gradual change in the cavity proportions due to decrease in the size in one of the directions. The problem is to determine the main physical aspects that define the heat and mass transfer under given conditions. The conducted experiments show that the hydrodynamic paradoxes occurring in thin cavities and channels become evident during the motion of multicomponent fluids. These flows can be represented as a multicomponent molecular solution flow through non-uniformly heated thin connected channels, a binary metal melt flow in a capillary with nonwettable boundaries, and a ferrocolloid flow in a convective loop. Sometimes the fluidic media demonstrate unexpected behavior as a result of viscous interaction with solid boundaries during the mixing of initially homogeneous fluids. It is worth emphasizing that anomalous behavior takes place in thin cavities and channels even when their dimensions are macroscopic. The common feature of the considered processes is that the fluid interaction with the cavity boundaries has a great effect on the heat and mass transfer. All the described hydrodynamic phenomena have been found experimentally, and many of them had no explanation for a long time. Currently, these processes with multicomponent fluids involved have been studied in details and have a quantitative description. It is possible to combine the theoretical and experimental results, and to understand these phenomena clearly.