The beasts'model of percolative transport

Many unsolved problems in physics, astrophysics or biology can be summarised as a discrepancy between experimentally observed fluxes of a quantity U and the fluxes which a simple theory would predict. This class of problems is usually referred to as 'anomalous transport'. Kelvin-Helmholtz-induced vortices in astrophysical accretion disks will be called 'beasts'. They are locallised processes, which themselves may depend on U. A Von Neumann object with two variables will be introduced which can be used to model such phenomena. One of these variables is the quantity U, and the other is a measure δ of the amplitude of the beasts. A simple case is shown that a wide range of behaviours is obtained. (R.P.) 3 refs.; 4 figs