Calculations of longitudinal and transverse velocity structure functions using a vortex model of isotropic turbulence

The longitudinal structure function (LSF) and the transverse structure func tion (TSF) in isotropic turbulence are calculated using a vortex model. The vortex model is composed of the Rankine and Burgers vortices which have th e exponential distributions in the vortex Reynolds number and vortex radii. This model exhibits a power law in the inertial range and satisfies the mi nimal condition of isotropy that the second-order exponent of the LSF in th e inertial range is equal to that of the TSF. Also observed are differences between longitudinal and transverse structure functions caused by intermit tency. These differences are related to their scaling differences which hav e been previously observed in experiments and numerical simulations. (C) 19 99 American Institute of Physics. [S1070-6631(99)02512-X].