ON VELOCITY AND PASSIVE SCALAR SCALING LAWS IN A TURBULENT SWIRLING FLOW

We analyze experimentally the statistical properties of velocity and t emperature fluctuations, considered as a passive scalar, in a turbulen t flow generated in the gap between coaxial disks. One of the disks is heated at a temperature higher than ambient, while the other one is c ooled. With this arrangement one obtains a flow with either positive, negative or null temperature-velocity correlations. The velocity, temp erature and heat flux fields are measured locally and studied via the moments of their increments. We find that the velocity field character istics are independent of the large scale anisotropy, with scaling law s in agreement with the ones generally observed in fully developed tur bulence. In contrast, the scalar field is strongly affected by the inj ection conditions at large scale; only in the central well-mixed regio n does one observe a behavior consistent with the existence of scaling . In the same region, the heat transport delta u delta T-2 follows the same scaling laws as the kinetic energy flux delta u(3).