Schematic representation of the vertical channel.
Budget of turbulence kinetic energy at different grid resolutions.
Streamwise and spanwise mean velocity components.
RMS of vorticity fluctuations; thick lines correspond to buoyancy induced 3DTBL and thin lines correspond to 2DTBL.
Budget of turbulence kinetic energy; thick lines correspond to buoyancy induced 3DTBL and thin lines correspond to 2DTBL.
Turbulence structure parameters a1.
RMS streamwise vorticity fluctuations.
RMS streamwise vorticity fluctuations based on its sign with different thresholds; (a) positive only and (b) negative only.
Joint probability density functions; (a) JPDF of u′ and v′; (b) weighted JPDF; (c) conditioned weighted JPDF with positive ω′ x ; and (d) conditioned weighted JPDF with negative ω′ x . Thin lines in (c) and (d) correspond to 2DTBL.
Contribution of each quadrant to the primary Reynolds shear stress and thin lines refer to non-buoyant channel.
Conditional average for strong v′ aty + ∼ 18; (a) p′; (b) ω′ x ; (c) −λ′2; strong arising v′ > 1.4 (——); and strong sinking v′ < −1.4 (······).
Cross-stream conditional average for strong streamwise vorticity; left column refers to ⟨u′⟩ with contour intervals 0.15; right column refers to ⟨v′⟩ with contours intervals 0.15; upper row refers to negative ω′ x ; middle row refers to positive ω′ x ; lower row refers to general sign of ω′ x ; and bold lines refer to the location and shape of the vortices.
Conditional average fields in cross stream plane cutting strong vortices; (a) negative; (b) positive; and contour levels of −u′v′ have 0.15 interval spacing.
Schematic of near-wall turbulence structures of buoyancy-driven 3DTBL flow in a frame moving with the center of the vortices.
Iso-surface of the conditional averaged vortices detected by −λ′2 ∼ 0.015 embedded over low speed streaks; (a) negative vortices; (b) positive vortices; and contours levels of u′ have 0.2 interval spacing.
Low-speed streaks spacing.
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