Speaker
Gerhard Gompper
(Institute of Complex Systems and Institute for Advanced Simulation, Germany)
Description
The flow behavior of vesicles and blood cells is important
in many applications in biology and medicine. For example,
the flow properties of blood in micro-vessels is determined
by the rheological properties of red blood cells (RBCs).
Blood flow is therefore strongly affected by diseases such
as malaria or diabetes, where RBC deformability is strongly
reduced. Furthermore, microfluidic devices have been
developed recently, which allow the manipulation of small
amounts of suspensions of particles or cells.
Of fundamental interest is here the relation between the
flow behavior and the elasticity and deformability of the
blood cells, their long-range hydrodynamic interactions in
microchannels, and thermal membrane undulations [1]. We
study these mechanisms by combination of particle-based
mesoscale simulation techniques [2] for the fluid
hydrodynamics with triangulated-surface models [3, 4, 5] for
the membrane. The essential control parameters are the
volume fraction of RBCs (tube hematocrit), the cell shape
and deformability, the flow velocity, and the capillary radius.
In narrow channels, single red blood cells in capillary flow
show a transition from the biconcave disk shape at low flow
velocities to a parachute shape at high flow velocities [4,
6]. For somewhat wider channels, other shapes such as
slippers intervene between these states [6]. At higher
volume fractions, hydrodynamic interactions are responsible
for a strong deformation-mediated clustering tendency at low
hematocrits, as well as several distinct flow phases at
higher hematocrits [7]. For large vessels, blood behaves
like a continuum fluid, which displays a strong
shear-thinning behavior; our simulations show quantitatively
how this behavior arises due to RBC deformability and
cell-cell attraction [8]. Finally, the interaction of RBCs
with other blood cells or drug carriers is shown to lead to
the margination of these particles at intermediate
hematocrits and not too large flow rates [9, 10].
The properties of sedimenting RBCs are also briefly
discussed [11].
[1] D. A. Fedosov, H. Noguchi, and G. Gompper. Multiscale
Modeling of Blood Flow: From Single Cells to Blood Rheology.
Biomech. Model. Mechanobiol. 13, 239-258 (2014).
[2] G. Gompper, T. Ihle, D. M. Kroll, and R. G. Winkler.
Multi-Particle Collision Dynamics - a Particle-Based
Mesoscale Simulation Approach to the Hydrodynamics of
Complex Fluids. Adv. Polymer Sci. 221, 1 (2009).
[3] G. Gompper and D. M. Kroll. Triangulated-Surface Models
of Fluctuating Membranes. In Statistical Mechanics of
Membranes and Surfaces, 2nd edition, edited by D. R. Nelson
and T. Piran and S. Weinberg (World Scientific, Singapore,
2004).
[4] H. Noguchi and G. Gompper. Shape Transitions of Fluid
Vesicles and Red Blood Cells in Capillary Flows. Proc. Natl.
Acad. Sci. USA 102, 14159 (2005).
[5] D. A. Fedosov, B. Caswell, and G. E. Karniadakis. A
multiscale red blood cell model with accurate mechanics,
rheology, and dynamics. Biophys. J. 98, 2215 (2010).
[6] D. A. Fedosov, M. Peltomäki, and G. Gompper. Shapes and
Deformation of Red Blood Cells in Microvessel Flows. Soft
Matter 10, 4258-4267 (2014).
[7] J. L. McWhirter, H. Noguchi, and G. Gompper.
Flow-Induced Clustering and Alignment of Red Blood Cells in
Microchannels. Proc. Natl. Acad. Sci. USA 106, 6039 (2009).
[8] D. A. Fedosov, W. Pan, B. Caswell, G. Gompper, and G. E.
Karniadakis. Predicting blood rheology in silico. Proc.
Natl. Acad. Sci. USA 108, 11772 (2011).
[9] D. A. Fedosov, J. Fornleitner, and G. Gompper.
Margination of White Blood Cells in Microcapillary Flow.
Phys. Rev. Lett. 108, 028104 (2012).
[10] K. Müller, D. A. Fedosov, and G. Gompper, Margination
of micro- and nano-particles in blood flow and its effect on
the effciency of drug delivery. Sci. Rep. 4, 4871 (2014).
[11] M. Peltomäki and G. Gompper, Sedimentation of Single
Red Blood Cells. Soft Matter 9, 8346{8358 (2013).
