The interaction between a solid particle and a turbulent flow

The interaction between a fixed solid spherical particle and stationary turbulence with zero mean flow is investigated numerically. The object diameter, D, lies in the inertial range (D approximate to 0.6L approximate to 0.9 lambda approximate to 8 eta, where L, lambda and eta, respectively, denote the integral scale, the Taylor microscale and the Kolmogorov length) and the particle Reynolds number is close to 20. It is found that the turbulence statistics at different distances from the solid/fluid interface are modified by the presence of the object in a region that extends more than 10 times further than the viscous layer. This estimate is confirmed by the analysis of the correlation between the force and torque on the particle and the force and torque on spherical surfaces surrounding the particle, although the torque decorrelates somewhat faster with increasing distance from the object surface. The angular slip velocity of the particle, a quantity of crucial importance for the modeling of the turbulent transport of large objects, is also characterized.