Locomotion of microorganisms near a no-slip boundary in a viscoelastic fluid.
Locomotion of microorganisms plays a vital role in most of their biological processes. In many of these processes, microorganisms are exposed to complex fluids while swimming in confined domains, such as spermatozoa in mucus of mammalian reproduction tracts or bacteria in extracellular polymeric matrices during biofilm formation. Thus, it is important to understand the kinematics of propulsion in a viscoelastic fluid near a no-slip boundary. We use a squirmer model with a time-reversible body motion to analytically investigate the swimming kinematics in an Oldroyd-B fluid near a wall. Analysis of the time-averaged motion of the swimmer shows that both pullers and pushers in a viscoelastic fluid swim towards the no-slip boundary if they are initially located within a small domain of "attraction" in the vicinity of the wall. In contrast, neutral swimmers always move towards the wall regardless of their initial distance from the wall. Outside the domain of attraction, pullers and pushers are both repelled from the no-slip boundary. Time-averaged locomotion is most pronounced at a Deborah number of unity. We examine the swimming trajectories of different types of swimmers as a function of their initial orientation and distance from the no-slip boundary.
Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Shahrzad
S
Yazdi
Department of Aerospace & Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA and School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Arezoo M
AM
Ardekani
Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Ali
A
Borhan
D001696:Biomechanical Phenomena; D008954:Models, Biological; D013550:Swimming; D055682:Viscoelastic Substances
D055682:Viscoelastic Substances