Longitudinal dispersion of turbulent oscillatory pipe flows

Axial dispersion in curved channels in the presence of pulsating flow

“…Our results for straight tubes are in agreement with experimental [40] and theoretical [15] findings in the literature, where, when the frequency is increased (at sufficiently high amplitude ratios), a rapid fall in axial dispersion is reported. Another literature source presents a reduction in the axial dispersion number when α/St exceeds 20-30 [36]. The onset of turbulence is the key mechanism for the reduction of axial dispersion in straight tubes, and based on literature findings, onset of turbulence or intermittent turbulence are expected in the system we considered.…”

“…Note that this correlation indicates a developed turbulent flow; weak turbulence is reported to occur at lower values of Re 𝛿𝛿 [34]. For example, a study has reported temporary turbulence during a change of flow direction at Re 𝛿𝛿 = 200 [36]. The onset of turbulence in pulsating flows is still being actively investigated, and the scientific community still has to agree on when it is expected to occur.…”

Surface wave propagation in coastal waters with viscoelastic boundaries

“…Adopting a Reynolds number in the form of Re = umax *  instead, where  is the boundary layer thickness, previous research (e.g. Song and Law, 2015) had shown that the laminar boundary layer will transit to partial turbulence when Re > ~150 and fully developed turbulence when Re > ~500 for a fixed boundary. The corresponding energy dissipation in the oscillatory turbulent boundary layer would be much higher than that of the laminar boundary layer.…”