Ali Najafi

Department of Physics, University of Zanjan, Zanjan 313, Iran



The study of propulsion mechanisms at very low Reynolds number has been the subject of many theoretical and experimental studies since the classical work of Taylor [1]. As has been indicated by Purcell, the exceptional constraints of the low Reynolds hydrodynamics introduce very interesting features for the problem of swimming in this condition [2]. A very comprehensive review of the subject can be found in reference [3].

Here after a very short look at the micron-scale hydrodynamics, we will consider the problem of bacterial chemotaxis, an interesting example of real world directed swimming motion.

Inspired by biological chemotaxis of bacteria along circular paths [4], we introduce and study the hydrodynamics of a model micro-swimmer. This micro-hunter is essentially a stochastic low Reynolds swimmer with ability to move and sense the local value of a chemical concentration emitted by a source [5, 6]. We show that by adjusting the geometrical and dynamical variables of the proposed swimmer we can always achieve a cswimmer that can navigate and search for the region with higher concentration of a chemical emitted by sources.

The aim of this presentation is to study on the interplay between the hydrodynamic details of a model swimmer and also the details of internal adaptation mechanism. In addition to this aim, the idea of this work can also be used for assembling an artificial search machine suitable for working at cellular environment .


[1] G. Taylor, Proc. R. Soc. Lond. A  209, 447 (1951).

 [2] E. Purcell, American Journal of Physics 45, 3 (1977).

 [3] E. Lauga and T. R. Powers, Rep. Prog. Phys. 72, 096601 (2009).

 [4] B. M. Friedrich, F. Julicher, Phys. Rev. Lett. 103, 068102 (2009).

 [5] A. Najafi, Phys. Rev. E  Rapid Communication 83, 060902  (2011).