par Maharana, Surya Narayan 
;Mishra, Manoranjan ;Rongy, Laurence ;De Wit, Anne
Référence Proceedings - Royal Society. Mathematical, physical and engineering sciences, 481, 2312, 20240891
Publication Publié, 2025-04-01
;Mishra, Manoranjan ;Rongy, Laurence ;De Wit, Anne Référence Proceedings - Royal Society. Mathematical, physical and engineering sciences, 481, 2312, 20240891
Publication Publié, 2025-04-01
Article révisé par les pairs
| Résumé : | Vertical viscosity stratification in a channel flow driven by a longitudinal pressure gradient may induce shear instabilities that deform the interface into convective roll-ups. The initial position of the viscosity stratification, classically fixed in miscible non-reactive systems, crucially influences shear conditions in channel or pipe flows. Here, we investigate numerically convective shear dynamics when the position of the mixing zone evolves in time around a travelling autocatalytic reaction-diffusion front exhibiting self-organized viscosity changes. We analyse how the intersection between the travelling front position and the appropriate shear regions influences the onset time of the convective dynamics and the properties of the roll-ups. To do so, we consider a two-layered flow in a two-dimensional channel, where a more viscous solution of the autocatalytic species in the bottom layer invades a less viscous reactant solution perpendicularly to the direction of shear flow. Linear stability analysis (LSA) of the reaction-diffusion-convection equations suggests that, if the autocatalytic front is initially positioned at an intermediate vertical level, the flow can reach its most hydrodynamically unstable state. The onset time of the convective dynamics obtained from nonlinear simulations matches the LSA predictions. Interestingly, nonlinear simulations highlight that the onset of roll-ups can be delayed while obtaining a maximum instability growth by tuning the speed of the autocatalytic chemical front. |
