The end of nanochannels
  Current theories of nanochannel flow impose no upper bound on flow rates, and predict friction through nanochannels can be vanishingly small. We reassess neglecting channel entry effects in extremely long channels and find violations at the nanoscale. Even in frictionless nanochannels, end effects provide a finite amount of friction. Hence, the speed at which nanochannels transport liquids is limited. Flow-rate and slip length measurements are reevaluated using calculations which include end-effect friction. End effects are critical for the design of new technological devices and to understand biological transport. 
Thomas B. Sisan and Seth Lichter
physics.flu-dyn