Cooperation of sperm in two dimensions: Synchronization, attraction, and aggregation through hydrodynamic interactions

Abstract

Sperm swimming at low Reynolds number have strong hydrodynamic interactions when their concentration is high in vivo or near substrates in vitro. The beating tails not only propel the sperm through a fluid, but also create flow fields through which sperm interact with each other. We study the hydrodynamic interaction and cooperation of sperm embedded in a two-dimensional fluid by using a particle-based mesoscopic simulation method, multiparticle collision dynamics. We analyze the sperm behavior by investigating the relationship between the beating-phase difference and the relative sperm position, as well as the energy consumption. Two effects of hydrodynamic interaction are found, synchronization and attraction. With these hydrodynamic effects, a multisperm system shows swarm behavior with a power-law dependence of the average cluster size on the width of the distribution of beating frequencies.

Estimation of the critical behavior in an active colloidal system with Vicsek-like interactions

“…However, from the multiple crossings one can use the average value as an estimate for the crossing point and the standard deviation as an estimate of error. For the critical colloid packing fraction we find η col crit = 0.103(5), while the critical polymer packing fraction is determined as η pol crit = 0.278 (8). While both cumulants U N (η col ) and U N (η pol ) cross for all subbox sizes analyzed, the crossing occurs at different state points.…”

“…We use a cubic simulation box with S = 48σ cc and subdivide the system into many small subboxes N = 8, 10, 12, 14, 16 to calculate the moments and cumulants as defined in Eqs. (6)- (8). The length of each subbox is then L = S/N .…”

“…Some bacteria are able to propel themselves and can show densitydependent phase separation 6,7 . Sperm cells cooperate due to hydrodynamic interactions and form clusters 8 . It is even possible to alter microorganisms and make them thereby active, e.g.…”

Behaviour and Population Dynamics of Entomopathogenic Nematodes Following Application

“…Other physical forces may also contribute to aggregation, and systems of self-propelled particles are known for their tendency to aggregate and display swarming behaviour (Yang, Marceau, & Gompper, 2010). For example, hydrodynamic interactions contribute to synchronisation and attraction of sperm (Yang, Elgeti, & Gompper, 2008). On the other hand, social behaviour in feeding Caenorhabditis elegans Maupas (Rhabditida.…”

Swimming at Low Reynolds Number: From Sheets to the African Trypanosome

“…Thermal fluctuations are inherent within the technique. MPCD has been widely used to study a variety of problems such as the dynamic properties of semiflexible polymers or sheets [2,7], single and collective behavior of micro swimmers at low Reynolds number [8,36], and sedimentation of colloids [24].…”