Measurements of Lagrangian drift induced by translating fluid vortices. Vortex is indicated by black arrow. (A) Vortex approaches several planar Lagrangian surfaces downstream of the vortex generator (several more planes further downstream not shown); "t"=0.07 s. (B,C) Fluid vortices interact with Lagrangian surfaces in a manner similar to that observed for the inviscid sphere solution. Initially planar surfaces are deformed to horn-like shapes; "t"=3.34 s and 13.3 s, respectively. (D–F) Individual Lagrangian particle paths corresponding to "t"=0.07 s, 3.34 s and 13.3 s, respectively.