RT Journal Article T1 A blow-up mechanism for a chemotaxis model A1 Herrero, Miguel A. A1 Velázquez, J.J. L. AB We consider the following nonlinear system of parabolic equations: (1) ut =Δu−χ∇(u∇v), Γvt =Δv+u−av for x∈B R, t>0. Here Γ,χ and a are positive constants and BR is a ball of radius R>0 in R2. At the boundary of BR, we impose homogeneous Neumann conditions, namely: (2) ∂u/∂n=∂v/∂n=0 for |x|=R, t>0. Problem (1),(2) is a classical model to describe chemotaxis, i.e., the motion of organisms induced by high concentrations of a chemical that they secrete. In this paper we prove that there exist radial solutions of (1),(2) that develop a Dirac-delta type singularity in finite time, a feature known in the literature as chemotactic collapse. The asymptotics of such solutions near the formation of the singularity is described in detail, and particular attention is paid to the structure of the inner layer around the unfolding singularity. PB Scuola Normale Superiore SN 0391-173X YR 1997 FD 1997 LK https://hdl.handle.net/20.500.14352/58709 UL https://hdl.handle.net/20.500.14352/58709 LA eng NO S. D. Eidelman, Parabolic systems, North-Holland, Amsterdam, 1969. R. M. Ford - D. A. Lauffenburger, Analysis of chemotactical bacterial distribution in population migration assays using a mathematical model applicable to steep or shallow attractant gradients, Bull. Math. Biol. 53 (1991), 721–749. E. F. Keller - L. A. Segel, Initiation of slime mold aggregation viewed as an instability, J. Theor. Biol. 26 (1970), 399–415. W. Jäger and S. Luckhaus, On explosions of solutions to a system of partial differential equations modelling chemotaxis, Trans. Amer. Math. Soc. 329 (1992), 819–824. M. A. Herrero - J. J. L. Velázquez, Singularity patterns in a chemotaxis model, Math. Ann. 306 (1996), 583–623. M. A. Herrero - J. J. L. Velázquez, Chemotactic collapse for the Keller-Segel model, J. Math. Biol. 35 (1996), 177–194. T. Nagai, Blow-up of radially symmetric solutions to a chemotaxis system, Adv. Math. Sci. Appl. (1995), 1–21. NO DGICYT DS Docta Complutense RD 7 may 2024