SCALE SIMILARITY OF THE VELOCITY STRUCTURE FUNCTIONS IN FULLY-DEVELOPED MAGNETOHYDRODYNAMIC TURBULENCE

Turbulence theory has been recently enriched by the concept of extende d self-similarity introduced by Benzi et al. [Phys. Rev. E 48, R29 (19 93)] which showed that an extended scaling range, including both the i nertial and the dissipative regions, can be observed when the usual qt h-order velocity structure functions are plotted against the structure function of the third order. The same concept has been reviewed by St olovitzky and Sreenivasan [Phys. Rev. E 48, R33 (1993)], whose high re solution measurements show the existence of two scaling regions which become increasingly distinct as the order of the velocity structure fu nction increases. In this paper, by using a shell model for three-dime nsional magnetohydrodynamic (MHD) turbulence, we show that the extende d self-similarity could be an interesting concept also in fully develo ped MHD turbulence.