Scaling of mixed longitudinal-transverse velocity structure functions

Measurements in a turbulent round jet at a Taylor microscale Reynolds number Rλ of about 500 indicate that the mixed structure functions of u, the longitudinal velocity fluctuation, and v, the transverse velocity fluctuation, show a larger departure from the Kolmogorov scaling than the u structure functions, and a smaller departure than the v structure functions. Although the scaling exponents of the temperature structure functions are nearly equal to those of the v structure functions at a comparable order, the mixed structure functions of u and the temperature fluctuation θ exhibits a smaller departure from the Kolmogorov scaling than either u or θ structure functions at the same order. The difference between the scaling behaviour of these two mixed structure functions mainly reflects the difference in correlation between (∂u/∂x)² and either (∂v/∂x)² or (∂θ/∂x)², implying that there is an important difference between temperature and velocity fields.