A driving mechanism of near-wall turbulence subject to adverse pressure gradient in a plane Couette flow

The effect of adverse pressure gradient (APG) on near-wall turbulence is studied, with a particular attention to the production mechanism. A plane turbulent Couette flow considered for several values constant APG in lower wall region. direct numerical simulation (DNS) large computational domain shows that near continues exist even at sufficiently APGs. On increasing APG, cross-streamwise intensities increase, and streaks gradually disappear. linear analysis using optimal transient growth indicates inhibits generation due significant reduction mean shear region wall. fluctuation dynamics beyond regime studied DNS minimal unit. self-sustaining process involving significantly weakened or destroyed as increases, while fluctuations become more isotropic localised. Using conditional averaging analysis, new mechanism under strong uncovered. This initiated by wall-normal nonlinear transport an outer velocity transported subsequently amplified via Orr mechanism, resulting non-zero spatially localised vortical structures. also confirmed domain, where correlation between observed.