Overlap with fluid dynamics

In nature, it is likely to encounter convective dissolution of many crystals. In this case, if their boundary layers do not overlap and the flow velocity fields do not overlap, each crystal may be viewed as dissolving individually without interacting with other crystals. However, if their boundary layers overlap or their flow velocity fields overlap, the above treatment would not be accurate. Furthermore, when there are many crystals, the whole parcel of crystal-containing fluid may sink or rise (large-scale convection), leading to completely different fluid dynamics. Such problems remain to be solved. 

Early modeling of fuel cells with a liquid electrolyte was focused mainly on the electrochemical problems of cell function [2], The invention of Nafion generated high expectations and investments, which supported study of numerous physical and engineering aspects of ceU operation. Today s fuel-cell science and technology include overlapping domains of electrochemistry, physics, fluid dynamics, and chemical and mechanical engineering. 

EDL field strength is of the order of 10 V/m, which is significantly higher than the typical electric field strengths ( kV/m) that are commonly employed to actuate fluid dynamic transport through microchannels. The far-stream boundary condition is applicable. This, however, loses its validity when the EDLs formed in vicinity of two narrowly-separated solid surfaces effectively protrude into the central plane that is located midway between the two surfaces and overlap with each other. 

A FIGURE 5-7 Gel and fluid forms of the phospholipid bilayer. (Top) Depiction of gel-to-fluid transition. Phospholipids with long saturated fatty acyl chains tend to assemble into a highly ordered, gel-like bilayer in which there is little overlap of the nonpolar tails in the two leaflets. Heat disorders the nonpolar tails and induces a transition from a gel to a fluid within a temperature range of only a few degrees. As the chains become disordered, the bilayer also decreases in thickness. Bottom) Molecular models of phospholipid monolayers in gel and fluid states, as determined by molecular dynamics calculations. 

---