Non-expert summaryThis is a review of the fluid mechanics associated with blistering, which occurs when a thin solid layer locally separates from an underlying substrate through cracking of a bulk material, delamination of a composite material, or peeling of a thin layer (membrane) adhered to the substrate by a thin layer of viscous fluid. The focus of the review is on the latter case, where the expansion of the newly formed blister by fluid injection occurs via a displacement flow, which peels the adhered surfaces apart through a two-way interaction between flow and deformation. These blisters are prone to fluid- and solid-mechanical instabilities. If the injected fluid is less viscous than the fluid already occupying the gap, patterns of short and stubby fingers (fingering) form on the propagating fluid interface. Buckling/wrinkling instabilities of the delaminated layer can arise for sufficiently thin membranes and can interact with the fluid mechanical fingering instability.
Non-expert summaryThe authors conduct a comprehensive numerical study of convective mass transport from 2-D rectangular cavities in low‐Reynolds‐number flows, i.e. the flow set up in a long rectangular trench by the motion of a steady shear flow across the top. They calculate the velocity field in the trench and the associated mass transport (enhancement of diffusion). The flow field is calculated by a high‐order implementation of the boundary‐integral method, while the convective diffusion equation is solved using the spectral‐element method. Results are presented in the form of concentraton contours and local mass fluxes, for cavity aspect ratios from 1:1 to 4:1 and for Péclet numbers from 0 to 100,000. They investigate the effects of inlet flow profile and system boundaries on the system.
Non-expert summaryWhen a steady shear flow passes over a long (2-D) cavity it sets up a circulation cell in the cavity, where the flow in the cavity is contained within the cavity (with a boundary called the separatrix) and mass transport into and out of the cavity is predominantly by diffusion. This is particularly true at small scales. The authors investigate numerically and experimentally two methods for enhancing mass transport from these 'cells' - by geometrically modifying the boundary driving the flow, and making the driving flow time-dependent. Both modifications destabilize one of the wall attachment points of the separatrix, allowing fluid exchange between the cavity and channel. The range of Reynolds and Reynolds-Strouhal numbers studied is 7.7 <= Re <= 46.5 and 0.52 <= ReSr <= 12,55 in the spatially dependent mode and 12 <= Re <= 93 and 0.26 <= ReSr <= 5.02 in the time-dependent mode. The transport is described theoretically via lobe dynamics, which characterizes the instability of the separatrix. They find that the resulting mass transfer between the cavity and the outer shear flow, through the distabilized separatrix is enhanced by several orders of magnitude compared to a diffusive mass transfer.