Abstract. We introduce a numerical scheme to approximate a quasilinear hyperbolic system which models the movement of cells under the influence of chemotaxis. Since we expect to find solutions which contain vacuum parts, we propose an upwinding scheme which properly handles the presence of vacuum and which gives a good approximation of the time asymptotic states of the system. For this scheme we prove some basic analytical properties and study its stability near some of the steady states of the system. Finally, we present some numerical simulations which show the dependence of the asymptotic behavior of the solutions upon the parameters of the system. Key words. Hyperbolic system with source, chemotaxis, stationary solutions with vacuum, finite volume methods, well-balanced scheme.AMS subject classifications. Primary: 65M08; Secondary: 35L60, 92B05, 92C17.
IntroductionThe movement of bacteria, cells or other microorganisms under the effect of a chemical stimulus, represented by a chemoattractant, has been widely studied in mathematics in the last two decades (see [18,22,23,26]), and numerous models involving partial differential equations have been proposed. The basic unknowns in these chemotactic models are the density of individuals and the concentrations of some chemical attractants. One of the most considered models is the Patlak-KellerSegel system [21], where the evolution of the density of cells is described by a parabolic equation, and the concentration of a chemoattractant is generally given by a parabolic or elliptic equation, depending on the different regimes to be described and on authors' choices. The behavior of this system is quite well known now: in the one-dimensional case, the solution is always global in time [24], while in two and more dimensions the solutions exist globally in time or blow up according to the size of the initial data; see [6,7] and references therein. However, a drawback of this model is that the diffusion leads alternatively to a fast dissipation or an explosive behavior, and prevents us from observing intermediate organized structures, such as aggregation patterns.In this paper, we consider a quasi-linear hyperbolic system of chemotaxis introduced by Gamba et al. [11] to describe the early stages of the vasculogenesis process, namely the formation of blood vessels networks during the embryonic development. The model forms a hyperbolic-parabolic system for the following unknowns: the density of endothelial cells ρ(x,t), their momentum ρu(x,t), and the concentration φ(x,t)