Simultaneous measurements of the fluid and the solid phases in homogeneous turbulence: preliminary results at Re_λ = 250

摘要

Two-phase turbulent flows are of great interest for a number of most important and extremely diverse application such as combustion, sedimentation, fluidized beds, settling and resuspension of organic material and contaminants in lakes, ocean, waste water management, evolution of clouds, rain formation and dust storms (see for example Crowe et al., 1998, Gyr and Kinzelbach, 2003, Burton & Eaton 2005 and references therein). In a turbulent flow the interaction between the second phase and the carrier fluid is important since, for example the nonlinear processes that redistribute energy between the scale of the energy containing eddies and the scales associated with the field of velocity derivatives, are two-way coupled with the spatial distribution of the second phase. In the case of dilute suspensions of solid particles, the small scale processes of turbulence were observed to be modified due to the effects such as inertial response of particles to fluid acceleration, gravitational effects and preferential concentration of particles (see e.g. Ferrante & Elghobashi, 2003). In particular, in the flow regions where the dispersed solid phase tends to accumulate (i.e., clusters), the two way coupling effects may be enhanced, leading to strong modification of the local processes of self-amplification of velocity derivatives (see e.g. Tsinober, 2001).