caa a22 4500 445330473 CHVBK 20180317142735.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s00285-010-0351-y doi (NATIONALLICENCE)springer-10.1007/s00285-010-0351-y Effective shear viscosity and dynamics of suspensions of micro-swimmers from small to moderate concentrations [Elektronische Daten] [V. Gyrya, K. Lipnikov, I. Aranson, L. Berlyand] Recently, there has been a number of experimental studies convincingly demonstrating that a suspension of self-propelled bacteria (microswimmers in general) may have an effective viscosity significantly smaller than the viscosity of the ambient fluid. This is in sharp contrast with suspensions of hard passive inclusions, whose presence always increases the viscosity. Here we present a 2D model for a suspension of microswimmers in a fluid and analyze it analytically in the dilute regime (no swimmer-swimmer interactions) and numerically using a Mimetic Finite Difference discretization. Our analysis shows that in the dilute regime (in the absence of rotational diffusion) the effective shear viscosity is not affected by self-propulsion. But at the moderate concentrations (due to swimmer-swimmer interactions) the effective viscosity decreases linearly as a function of the propulsion strength of the swimmers. These findings prove that (i) a physically observable decrease of viscosity for a suspension of self-propelled microswimmers can be explained purely by hydrodynamic interactions and (ii) self-propulsion and interaction of swimmers are both essential to the reduction of the effective shear viscosity. We also performed a number of numerical experiments analyzing the dynamics of swimmers resulting from pairwise interactions. The numerical results agree with the physically observed phenomena (e.g., attraction of swimmer to swimmer and swimmer to the wall). This is viewed as an additional validation of the model and the numerical scheme. Springer-Verlag, 2010 Gyrya V. Department of Mathematics, The Pennsylvania State University, 16802, University Park, PA, USA aut Lipnikov K. Los Alamos National Laboratory, MS B284, 87545, Los Alamos, NM, USA aut Aranson I. Division of Material Science, Argonne National Laboratory, Argonne, IL, USA aut Berlyand L. Department of Mathematics, The Pennsylvania State University, 16802, University Park, PA, USA aut Journal of Mathematical Biology Springer-Verlag 62/5(2011-05-01), 707-740 0303-6812 62:5<707 2011 62 285 https://doi.org/10.1007/s00285-010-0351-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00285-010-0351-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Gyrya V. Department of Mathematics, The Pennsylvania State University, 16802, University Park, PA, USA aut NATIONALLICENCE 700 1- Lipnikov K. Los Alamos National Laboratory, MS B284, 87545, Los Alamos, NM, USA aut NATIONALLICENCE 700 1- Aranson I. Division of Material Science, Argonne National Laboratory, Argonne, IL, USA aut NATIONALLICENCE 700 1- Berlyand L. Department of Mathematics, The Pennsylvania State University, 16802, University Park, PA, USA aut NATIONALLICENCE 773 0- Journal of Mathematical Biology Springer-Verlag 62/5(2011-05-01), 707-740 0303-6812 62:5<707 2011 62 285 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer