Different intermittency for longitudinal and transversal turbulent fluctuations

Scaling exponents of the longitudinal and transversal velocity structure functions in numerical Navier-Stokes turbulence simulations with Taylor-Reynolds numbers up to Re-lambda=110 are determined by the extended self similarity method. We find significant differences in the degree of intermittency: For the sixth moments the scaling corrections to the classical Kolmogorov expectations are delta xi(6)(L)=-0.21+/-0.01 and delta xi(6)(T)=-0.43+/-0.01, respectively, independent of Re-lambda. Also the generalized extended self similarity exponents rho(pq)=delta xi(p)/delta xi(q) differ significantly for the longitudinal and transversal structure functions. Within the She-Leveque model this means that longitudinal and transversal fluctuations obey different types of hierarchies of the moments. Moreover, the She-Leveque model hierarchy parameters beta(L) and beta(T) show small but significant dependences on the order of the moment. (C) 1997 American Institute of Physics. [S1070-6631(97)03412-0].