Analysis and interpretation of instantaneous turbulent velocity fields

Methods of analyzing and interpreting velocity-field data (both two- and th ree-dimensional) to understand the kinematics, dynamics, and scales of turb ulence are discussed. Reynolds decomposition and vorticity are traditionall y used; however, several other methods, including Galilean (constant convec tion velocity) and LES decompositions (low-pass filtering), in conjunction with critical-point analysis of the local velocity gradient tensor, reveal more about the structure of turbulence. Once the small-scale structures hav e been identified, it is necessary to assess their importance to the overal l dynamics of the turbulence by visualizing the motions they induce and the stresses they impose both on other small-scale vortices and on the larger- scale field.