Ricerc@Sapienza

The present projects aims at shedding light onto the structure of turbulence in ducts and channels with complex shape. A primary objective will be characterizing the nature and strength of the secondary motions which arise, and which are not present in canonical flows, e.g. plane channel and pipe flow. Direct numerical simulations (DNS) will be used as a high-fidelity tool to obtain full information on the statistical properties of the flows. Several geometries will be considered, including rectangular, trapezoidal and semi-circular ducts, with either closed or open upper boundary, hence also covering flows relevant for the hydraulic engineering. The numerical solver will rely on the immersed-boundary method, which will also be used to carry out numerical simulations of rectangular duct flow with embedded complex geometries, as those found for instance in the cooling channels of rocket engines. The DNS database herein developed will be used as a basis for the assessment and development of advanced turbulence models based on the Reynolds-averaged Navier-Stokes equations. Significant impact of the study is foreseen in terms of improved prediction of heat and momentum transfer in internal flows, and of mechanisms of sedimentation and erosion in closed and open channels.