Modelling and simulation of deformable particles in external flow fields at negligible and finite inertia
- Event time: 1:00pm
- Event date: 10th February 2014
- Speaker: Timm Kruger (School of Engineering)
- Location: Room 2511, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB
Suspensions of soft particles are ubiquitous in nature. One of the most biologically important examples is blood which is a moderately dense suspension of red blood cells (RBCs). Due to their generally complex structure, it is rather difficult to study soft matter systems analytically. In many cases computer simulations are indispensable. Therefore, I will first provide a concise overview of my employed numerical model, which contains immersed-boundary, lattice-Boltzmann and finite-element components. In the second part of the talk, I will speak about the microstructure and rheology of RBC suspensions at small Reynolds numbers. We have recently shown that the well-known tumbling-to-tank-treading transition of isolated RBCs also takes place in denser suspensions and that this is accompanied by an orientational transition of the suspension microstructure. Motivated by the dynamical properties of RBCs under confinement, it is furthermore possible to construct an effective theoretical model and to predict the viscosity of blood over a remarkably large parameter range, spanning several orders of magnitude in shear rate as well as volume fractions between 10 and 90%. In the third and final part, I will show some recent results obtained for soft particle suspensions at finite Reynolds number. We found that the interplay of inertia and deformability has a substantial impact on the transport of those particles in a Poiseuille flow. Firstly, the Segré-Silberberg effect is suppressed when the particles becomes softer. Secondly, depending on the deformability and strength of inertial effects, inward or outward lateral migration of the particles takes place. In particular, for increasing Reynolds number and strongly deformable particles, distinct flow focusing emerges. This is accompanied by a non-monotonic behaviour of the apparent suspension viscosity.
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..