tl;dr: life predictably sticks at the sharp convex corners.
[it’s an article on biofilm]. Now what I want to know about is the “blue zone” corners where it looks-like nothing is happening.
“(a) Numerical results of the modulus of the velocity field in a plane at ¼ of the channel height from the upper surface. Coordinate system (x, y, z) and colour scale are shown. (b) Flow components perpendicular to the primary flow (represented here with streamlines) in the same plane as (a). Red and blue colours indicate here velocity components orthogonal to the plane of the channel, and directing, respectively, upwards (positive y) and downwards (negative y). (c) Prospective view of the channel showing pairs of counter-rotating vertices in cross-sectional planes right before and after the turns. (d) A cross-section of the channel, right after a turn. Arrows show the motion of fluid elements in the secondary flow. (e,f) Comparisons between numerical simulations of the secondary flow and experimental observations of the streamers, in a curved channel (e) and in a straight channel with a lateral hemi-cylindrical bump (f) (scale bars, (e) 50 μm; (f) 25 μm).”