Fig. Test BMC diffusiophoretic transport velocity V (z) for two-blocker system. The central blocker has radius 5R and the second blocker varies in radius. Both blockers have consumption rate J -= 10 -2 mol m -2 s -1 . The near-vertical lines close to z = 0 represent the velocity profile for a test particle in between the two blockers, where the consumption of both blockers causes a steep gradient in concentration.