Numerical Simulation of Turbulent Flow Control at Pipe Inlet to Advance Flow Relaminarization

Various methods of flow relaminarization in a pipe are considered by means of controlling the average and turbulent flow parameters. For numerical simulation of flows with turbulence growth and suppression it is proposed to use a three-parameter RANS turbulence model, which has shown good results in modeling existing experiments on relaminarization. Calculations for three variants of inlet devices with different velocity profiles and the same small-scale turbulence at the inlet show the possibility of achieving flow relaminarization in pipes at Reynolds numbers Re > 10 000. Among three variants of inlet devices considered, the most effective one is the variant with organization of a two-zone flow with slow flow in the central region of the pipe and accelerated flow in the near-wall region. In this version, relaminarization occurs up to the Reynolds number Re* = 16 000. It is shown that decrease in the turbulence intensity and scale leads to an even larger value of the relaminarization Reynolds number Re*.