Alcove formation in dissolving cliffs driven by density inversion instability

Fuente: arXiv
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Main Authors: Sharma, Ram Sudhir, Berhanu, Michael, Kudrolli, Arshad
Format: Preprint
Published: 2021
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author Sharma, Ram Sudhir
Berhanu, Michael
Kudrolli, Arshad
author_facet Sharma, Ram Sudhir
Berhanu, Michael
Kudrolli, Arshad
contents We demonstrate conditions that give rise to cave-like features commonly found in dissolving cliffsides with a minimal two-phase physical model. Alcoves that are wider at the top and tapered at the bottom, with sharp-edged ceilings and sloping floors, are shown to develop on vertical solid surfaces dissolving in aqueous solutions. As evident from descending plumes, sufficiently large indentations evolve into alcoves as a result of the faster dissolution of the ceiling due to a solutal Rayleigh-Bénard density inversion instability. By contrast, defects of size below the boundary layer thickness set by the critical Rayleigh number smooth out, leading to stable planar interfaces. The ceiling recession rate and the alcove opening area evolution are shown to be given to first order by the critical Rayleigh number. By tracking passive tracers in the fluid phase, we show that the alcoves are shaped by the detachment of the boundary layer flow and the appearance of a pinned vortex at the leading edge of the indentations. The attached boundary layer past the developing alcove is then found to lead to rounding of the other sides and the gradual sloping of the floor.
format Preprint
id arxiv_https___arxiv_org_abs_2111_12510
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Alcove formation in dissolving cliffs driven by density inversion instability
Sharma, Ram Sudhir
Berhanu, Michael
Kudrolli, Arshad
Fluid Dynamics
Soft Condensed Matter
Pattern Formation and Solitons
We demonstrate conditions that give rise to cave-like features commonly found in dissolving cliffsides with a minimal two-phase physical model. Alcoves that are wider at the top and tapered at the bottom, with sharp-edged ceilings and sloping floors, are shown to develop on vertical solid surfaces dissolving in aqueous solutions. As evident from descending plumes, sufficiently large indentations evolve into alcoves as a result of the faster dissolution of the ceiling due to a solutal Rayleigh-Bénard density inversion instability. By contrast, defects of size below the boundary layer thickness set by the critical Rayleigh number smooth out, leading to stable planar interfaces. The ceiling recession rate and the alcove opening area evolution are shown to be given to first order by the critical Rayleigh number. By tracking passive tracers in the fluid phase, we show that the alcoves are shaped by the detachment of the boundary layer flow and the appearance of a pinned vortex at the leading edge of the indentations. The attached boundary layer past the developing alcove is then found to lead to rounding of the other sides and the gradual sloping of the floor.
title Alcove formation in dissolving cliffs driven by density inversion instability
topic Fluid Dynamics
Soft Condensed Matter
Pattern Formation and Solitons
url https://arxiv.org/abs/2111.12510