Integrating macroscopic geometry and fluid-fracture feedback in dissolution analysis beyond isolated factors

The acidic dissolution behavior of calcite is an important process associated with geological environments such as karst-related systems and carbonate weathering. The study investigates the fundamental coupling mechanisms among geometric characteristics, fluid transport, and dissolution kinetics through controlled numerical simulations. The core innovation lies in the systematic quantification of the independent impact of the macroscopic curvature (represented by the aspect ratio Rm) on dissolution kinetics by introducing the parameter "Curvature-Dissolution Rate Coupling Response Coefficient (RC)" for the first time, and in revealing the interplay between two-dimensional fracture structure and fluid dynamics. Two-dimensional geometric models of isolated calcite particles and fractured matrices were established coupled with a dynamic mesh approach. For elliptical particles, the dissolution rate initially decreases and then increases with increasing Rm, a trend consistent with the variation of the specific surface area analogy value (B_v). The variation of RC indicates that the reaction rate is highly sensitive to curvature changes when Rm < 1. Multiple nonlinear regression analysis (Sd = 0.037 V_a^0.763ac^1.822Rm^-0.283 (R² = 0.972)) further reveals that among the acid injection rate (V_a), acid concentration (ac), and aspect ratio (Rm), ac exerts the most dominant control on the shrinkage degree (Sd). At the fracture scale, acid etching drives the morphology toward channelization and significantly attenuates the nonlinear behavior of fluid flow, clarifying the dynamic feedback mechanism inherent in fluid-fracture interaction.