Competition of intrinsic and topographically imposed patterns in Bénard–Marangoni convection

Abstract

The structure of Bénard–Marangoni convection cells can be controlled by periodic topographic patterns on the heated surface that generates the convection. When the periodicity of the topographic pattern matches the intrinsic periodicity of the convection cells, a convective pattern is formed that is 1:1 commensurate with the topographic pattern. Arrays of hexagonal, square, and triangular convection cells were generated over the appropriately designed topographic patterns, and visualized by infrared imaging. For imposed patterns with periodicity in two dimensions, as the ratio of the intrinsic and perturbing length scales changes, the pattern of the convection cells shows sharp transitions between different patterns commensurate with the imposed pattern. For imposed patterns with periodicity in one dimension (i.e., lines) the convection cells use the unconstrained dimension to adapt continuously to the external perturbation. Topographically controlled convection cells can be used to assemble microscopic particles into externally switchable regular lattices.

Marangoni convection and heat transfer in thin liquid films on heated walls with topography: Experiments and numerical study

“…9 On the other hand, if the substrate has a structure on its upper surface, the convection prevails for any temperature difference, even if the substrate is of a uniform temperature. 10 It occurs due to the inhomogeneity, which is imposed on the interface temperature by the spatial structure of the substrate. Moreover, the structure modifies flow patterns, thus affecting the heat and mass transport within the liquid.…”

Maze solving using temperature-induced Marangoni flow

“…An extension of our method would be using topographically controlled Bénard-Marangoni cells for maze solving, in which the motion of particles could be externally driven. 38 Additionally, we showed by simple theoretical calculations that in our setup (where the depth of the channel is negligible compared to its length), and provided that Ra<<Ma, the driving phenomenon for mass transfer is the thermocapillary effect. In this way, we provided an additional unconventional computing method for maze solving.…”

Regulation of tack development of acrylate films by the properties of the support

“…13,14 The ⌬T used to calculate the Ma number is the difference between the maximum and minimum temperature measured by IR thermography on the surface of the film during the initial stages of drying, which was taken as the first 10 s. Similar results were obtained when data from the first five or 20 s were used, except that the deviation in the data at 5 s (2.8%) was slightly greater than that (1.1%) measured at 10 or [17][18][19] No temperature dependence is assumed in these values because the overall thermal response of the films does not change with the substrate on which they are deposited. The differences are on a length scale associated with the size of the impurities that lead to nonuniform heat transfer.…”