Ultra-sharp pinnacles sculpted by natural convective dissolution.
Jinzi Mac Huang1, Joshua Tong1, Michael Shelley2,3
1Applied Math Lab, Courant Institute, New York University, New York, NY 10012.
Summary
Dissolving solids in liquid can form sharp spires, similar to natural karst stone forests. This process involves self-generated fluid flows that enhance dissolution, creating ultra-fine structures through an autogenic mechanism.
Area of Science:
- Geomorphology
- Physical Chemistry
- Fluid Dynamics
Background:
- Natural landscapes feature intricate karst morphologies, such as stone forests with sharp pinnacles, formed by mineral dissolution.
- The exact mechanisms behind the formation of these sharp spires are not fully understood due to complex environmental conditions.
Purpose of the Study:
- To investigate the formation of sharp spires from dissolving solids under simplified laboratory conditions.
- To develop a mathematical model explaining the role of fluid dynamics in pinnacle formation.
Main Methods:
- Laboratory experiments using solidified sugars dissolving in water.
- Observation of fluid flow patterns along the dissolving solid boundary.
- Development and simulation of a mathematical model linking dissolution, fluid flow, and shape evolution.
Main Results:
- Needlelike pinnacles and "bed-of-nails" arrays robustly formed from smooth solids.
- Dissolution-induced convective flows were observed, with dense fluid descending along the boundary.
- Mathematical modeling and simulations confirmed a feedback loop driving shape evolution towards a singularity, limited by microscale features.
Conclusions:
- A simple dissolution process in a closed system can robustly generate ultra-fine, sharp spires.
- Autogenic convective flows play a crucial role in enhancing dissolution and shaping the solid.
- This mechanism provides insight into the formation of natural karst pinnacles and other fine-scale geological structures.
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