On Complexity of Direction in Two-dimensional Fluid Flow
by
Amitabha Chanda
Indian Statistical Institute

Speed and direction of two-dimensional flow, measured at equal intervals are studied from Lagrangian view-point. From two succesive pairs of datar realised by the probe the relative velocity of the second particle to which the second pair of data is related with respect to the first particle is determined. This gives the angle of divergence of the two succesive particles reaching the probe. Angles thus estimated form a time-series. It is argued that the investigation of this time series would reveal some of the underlying characteristics of the complex nature of the dynamical system pertaining to the fluid flow. Self-similarity of the angle of divergence is studied from the time series by calculating the multifractal dimensions like fractal dimension and information dimension. A few cases using wind data are studied. Results obtained are compared with those obtained from the statistical parameters like standard deviation and entropy.

Date received: September 14, 2001