Multiscaling properties on sequences of turbulent plumes images

A multifractal analysis on a finite-range-scale of the plume concentration images at different experimental conditions (the height of the source Ho), where the measure is the grey value of the image (from 0 to 255), was applied to study its structure through time. The multifractal spectrum showed the characteristic inverse U-shape and a similar evolution in all Ho. The variation of the Hölder exponent (Δα) presented different amplitudes at different moments and increased with time. The symmetry of the spectrum (Δf) decreased with time achieving negative values (from left hand asymmetry evolving to right asymmetry). We show the different behaviour of axial velocity (W) with Δα and Δf. There is a linear relation of entrainment coefficient (αe) and the entropy dimension (α1). Therefore, the multifractal spectrum and the derived parameters can be used as markers of plume evolution as well as to study the effect of experimental conditions.