%0 Book Section %1 statphys23_1075 %A Becco, C. %A Vandewalle, N. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K behavior collective computer simulation statphys23 topic-10 %T A Vicsek-like model for fish school: clustering and other effects. %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=1075 %X We propose a new model of self-propelled particles. It is basically the same as the one by Vicsek, except that we let the velocity be variable. So, each particle is a point, interacting with the nearest particles. At each time step, the new velocity of a particle is given by $|v'|=łeft<|v|\right>+\eta$ and $þeta'=łeft<þeta\right>+\sigma$, where the means are computed over the particles being within a certain distance of interaction, $þeta$ being the orientation of the velocity vector and $\eta$ and $\sigma$ being two gaussian noises. Starting from a random situation, the system reach an equilibrium state, depending on the simulation's parameters. We tested the model for various value of the density and for different values of the maxima for the two noises. We tried some simulations introducing a viscosity-like effect. Mainly, the resulting equilibrium states were characterised by an order parameter, defined as $\Phi=|łeft<þeta\right>|$, the mean being computed over all the particles. We also computed other parameters, such as the size of the cluster in the final state, and the structure of this cluster, if it exists. Like in the Vicsek model, we found some transition in the order parameter $\Phi$ as a function of the density of particles $\rho$, but we also observe some new behaviour, such as clustering.

@incollection{statphys23_1075, abstract = {We propose a new model of self-propelled particles. It is basically the same as the one by Vicsek, except that we let the velocity be variable. So, each particle is a point, interacting with the nearest particles. At each time step, the new velocity of a particle is given by $|\vec v'|=\left<|\vec v|\right>+\eta$ and $\vec \theta'=\left<\vec \theta\right>+\sigma$, where the means are computed over the particles being within a certain distance of interaction, $\theta$ being the orientation of the velocity vector and $\eta$ and $\sigma$ being two gaussian noises. Starting from a random situation, the system reach an equilibrium state, depending on the simulation's parameters. We tested the model for various value of the density and for different values of the maxima for the two noises. We tried some simulations introducing a viscosity-like effect. Mainly, the resulting equilibrium states were characterised by an order parameter, defined as $\Phi=|\left<\vec \theta\right>|$, the mean being computed over all the particles. We also computed other parameters, such as the size of the cluster in the final state, and the structure of this cluster, if it exists. Like in the Vicsek model, we found some transition in the order parameter $\Phi$ as a function of the density of particles $\rho$, but we also observe some new behaviour, such as clustering.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Becco, C. and Vandewalle, N.}, biburl = {https://www.bibsonomy.org/bibtex/2bccf25cf6158640abc8c6ec559f3d8d2/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {f9b07830f10592174b6ae0386b9c8158}, intrahash = {bccf25cf6158640abc8c6ec559f3d8d2}, keywords = {behavior collective computer simulation statphys23 topic-10}, month = {9-13 July}, timestamp = {2007-06-20T10:16:38.000+0200}, title = {A Vicsek-like model for fish school: clustering and other effects.}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=1075}, year = 2007 }