Turbulent mass transfer in a drag-reducing channel flow with dosed polymer solution by simultaneous PIV and PLIF measurements

A Short Review on Drag-Reduced Turbulent Flow of Inhomogeneous Polymer Solutions

“…The Sc also decreased in streamwise direction along the flat plate showing loss of polymer effectiveness in the slotinjection case. In contrast, the measured Sc was found to increase in streamwise direction along the blowing wall for wall-blowing case due to the increasing concentration [87].…”

“…The measured Sc near the wall in the drag-reduced flow is found to be significantly greater than that of water flow (Sc ≈ 1). The high Sc indicates that the turbulent mass flux is affected by the action of the polymer and the dispersion away from the wall is reduced [48,87]. In Somandepalli et al's work [48], the largest Sc magnitude was around 6 and the measured Sc was found to increase with increasing concentration of the injected polymer solutions.…”

“…[48]. The black lines denote the results of the wall-blowing case with 100 ppm polymer solution blown obtained in [87]. 0 is the concentration of the injected polymer solution, equals half channel height for channel flow but equals boundary layer thickness for TBL.…”

“…The spatial turbulent mass fluxes and turbulent Schmidt number (Sc , expressed by (3), represents the relative intensities of the turbulent diffusivity of momentum and of mass) have been measured and adopted to quantitatively evaluate the effects of polymer diffusion [87,89]. Consider…”

“…With the increasing DRs, they also decrease and the peaks in the wall-normal profiles move away from the wall. However, as the polymers begin to mix quickly and lose effectiveness at farther downstream positions in the slot-injection case, the magnitudes of the wall-normal turbulent mass fluxes increase which indicates an increase in the wall-normal mixing in the boundary layer [48,87,90].…”