  We use singular value decomposition techniques to generalize the wavelet
transform modulus maxima method to the multifractal analysis of vector-valued
random fields. The method is calibrated on synthetic multifractal 2D vector
measures and monofractal 3D fractional Brownian vector fields. We report the
results of some application to the velocity and vorticity fields issued from 3D
isotropic turbulence simulations. This study reveals the existence of an
intimate relationship between the singularity spectra of these two vector
fields which are found significantly more intermittent than previously
estimated from longitudinal and transverse velocity increment statistics.
