LOW-FREQUENCY FLUCTUATIONS IN THE FLOW OVER CONFINED CYLINDER IN A NARROW RECTANGULAR DUCT AT Re = 3 750

Flows between two closely spaced bounding surfaces are frequently appear in engineering applications and natural flows. In current paper the flow over a cylinder in a narrow rectangular duct was investigated by numerical computations of Navier-Stokes equations using Large eddy simulations (LES) at Re_D = 3 750 based on cylinder diameter and the bulk velocity at inflow boundary. The influence of the bounding walls was demonstrated by comparing mean flow streamlines with the flow over an infinite cylinder at close Reynolds numbers. A comparison between the time-averaged velocity field in front and past the cylinder with experimental from the literature data showed good agreement although the characteristic horseshoe vortex structures are highly sensitive to Reynolds number and turbulence level at inflow boundary. Most energetic modes in recirculating region were revealed by spectral analysis. These low-frequency modulations were characterized by the pair of dominating vortices which are expected to have high influence on the heat transfer in near wake of the cylinder.

Keywords:
turbulence, flow over cylinder, shallow wake shear flow.
УДК 532.517.4

LOW-FREQUENCY FLUCTUATIONS IN THE FLOW OVER CONFINED CYLINDER IN A NARROW RECTANGULAR DUCT AT Re = 3 750