Doubling the period in a turbulent pulsating flow

Abstract

In this work, a numerical study of pulsating turbulent flows in pipes of round and square cross sections was carried out. The bulk flow velocity changes proportionally to 1+β sin (ωt) at β  = 1. For all studied values of the Reynolds number from Re = 4000 to Re = 8000, it was found that for small periods T=2π/ω of flow oscillations, the mean characteristics of turbulence change periodically in time with a period of T, and at large values of T, the flow becomes laminar. The most interesting thing is that at intermediate values of T, the turbulence characteristics change periodically in time, but with a period twice as long as the period of flow oscillations.