SIMPLE PASSIVE SCALAR ADVECTION-DIFFUSION MODEL

This paper presents a simple, one-dimensional modal of a randomly adve cted passive scalar. The model exhibits anomalous inertial range scali ng for the structure functions constructed from scalar differences. Th e model provides a simple computational test for recent ideas regardin g closure and scaling for randomly advected passive scalars. Results s uggest that high order structure function scaling depends on the large st velocity eddy size, and hence scaling exponents may be geometry dep endent and nonuniversal. [S1063-651X(98)11410-1].