Start
Sep 02, 2015 - 17:00
End
Sep 02, 2015 - 18:00
Venue
Room 149 Department of Chemical Engineering.
Event Type
Speaker
Prabhakar Ranganathan Snr. Lecturer Department of Mechanical & Aerospace Engineering Monash University Clayton campus - Bldg. 82 #349
Title
Mechanical behaviour of suspensions of motile particles
Abstract: The mechanics of motility of single microorganisms has held the fascination of physicists and engineers for a very long time. It is however only in 2005 that Hatwalne and Ramaswamy noted in a landmark article that self-propulsion of single cells must have interesting consequences for the overall mechanical behaviour of their suspensions. Since then there has been an explosion of work on materials consisting of self-propelled particles or ``active matter". And with good reason: understanding their properties appears to hold the key to understanding many complex biological processes. I shall present some of my group's current work in this area. The first concerns experiments testing a well known prediction of the theory for active matter that motility of particles changes the macroscopic bulk viscosity of their suspensions. Qualitative predictions in the article by Hatwalne and Ramaswamy have been broadly verified in experiments with suspensions of swimming algae and bacteria. I shall discuss our attempts at making a more quantitative comparison using experiments with extensional flows. The second half of the talk will focus on a ongoing collaborative work with Sameer Jadhav. It is known that bacteria build complex communities on surfaces called biofilms. Some organisms such as the "superbug" Pseudomonas aeruginosa rapidly colonize surfaces as monolayers before developing into mature biofilms. Experiments suggest that P. aeruginosa may employ an intriguing strategy to manipulate interfacial instabilities to quickly overrun soft surfaces. I shall discuss a preliminary attempt at building a mathematical model of interfaces in active materials such as these bacterial colonies. All are invited for the seminar in Chemical Engineering Department.NOT mandatory for CL702/704