Fig. 1.

Modified schematic of the flow chamber originally described in (7). a: Flow enters between 2 parallel surfaces with uniform height to produce a wall shear stress (WSS) of 3.5 Pa with zero gradient. b: Flow accelerates as the channel tapers to a narrower height, creating positive WSS gradient (WSSG; +980 Pa/m). c: Flow enters 2 more parallel surfaces to produce WSS of 28.4 Pa with zero gradient. d: Flow decelerates as the channel height increases, creating negative WSSG (−1,120 Pa/m). e: Flow recovers the original height to again produce uniform WSS of 3.5 Pa with zero gradient.