| Wed August 5th 2015 16:00 – 17:00 ZH286 | Seminar | Living on the edge: Bacterial traffic in confined flows Ernesto Altshuler |
Details:Fluid flow is present in natural and artificial environments where bacteriainhabit, like animal and plant vasculature, natural porous media and medical devices. However, the dynamics of bacteria in the presence of flows has been rarely studied in a quantitative fashion. In this talk, we explain our quantitative experimental results in the transport of E. coli near the walls of microfluidic channels, and in more detail along the edges formed by the interception of two perpendicular walls. Our experiments establish the connection between bacterial motion at the flat surface and at the edges, and demonstrate the robustness of the upstream motion along them. Upstream migration of E. coli at the edges is possible at much larger flow rates compared to motion at flat surfaces. We show that upstream motion not only takes place at the edge but also in an ‘‘edge boundary layer’’ whose size varies with the applied flow rate. We rationalize our findings as a function of local variations in the shear rate in the rectangular channels and hydrodynamic attractive forces between bacteria and walls. Finally, we present some consequences of the upstream motion of E. coli in confined geometry, such as the anomalous concentration of bacteria past a constriction, and the possibility of net upstream contamination along a very thin channel. | ||
