An idealised model of turbulent dispersion: two rectangular pulse initial condition

An idealised model of turbulent dispersion was introduced by Zimmerman and Chatwin in 1995 and it was further developed by Mole and Yeun in 2007, for the case of an initial concentration field consisting of one rectangular pulse. Here we extend this model to the case of two initial pulses in order to investigate the effect of varying concentration. We present analytical and numerical results for the dependence of the variance, skewness, kurtosis and probability density function of concentration on time and on the pulse locations and concentrations. For moderately large concentration difference between the pulses, one Pulse dominates and the behaviour is close to that for the one pulse case. This suggests that a model incorporating distributions Of Pulse separations and concentrations can be constructed by averaging over an ensemble of one pulse cases. The distributions used would be those appropriate to the 'strands' of highest concentration. Copyright (C) 2008 John Wiley & Sons, Ltd.