The dispersion of swimming algae: consequences for photobioreactors
- Event time: 1:00pm
- Event date: 27th May 2013
- Speaker: Ottavio Croze (University of Edinburgh)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Many microorganisms swim in directions biased by environmental cues. A well-studied example is the directed motion of the bacterium E.coli up (down) nutrient (poison) gradients (chemotaxis). Swimming algae have also evolved 'taxes'. For example, bottom-heavy algae are biased by a gravitational torque to swim upwards (gravitaxis). In flows, a viscous torque also acts on a swimmer, biasing it to swim to low shear regions (gyrotaxis). Such biases lead to surprising collective behaviour: gyrotactic swimmer suspensions are hydrodynamically unstable, breaking up into stunning patterns. In many biotechnological applications suspensions of microorganisms are flowed within conduits (e.g. photobioreactors for algal culture). The efficiency of these technologies depends on our ability to predict suspension behaviour, but the biased swimming of many useful organisms is ignored in engineering design. Inspired by this, I have theoretically and experimentally investigated the dispersion gyrotactic algae in pipes/channels. I will show how the active dispersion of swimmers can be very different from that of passive particles (e.g. molecules or colloids). Finally, I will discuss the implications of my findings for air-lift photobioreactors.
This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..