Mathematical Modeling and FEM Based Numerical Simulations of Seepage and Heat Transfer Dynamics between the Rock Matrix and a Single Fracture Using Ternary Hybrid Nanofluids

This study quantifies this thermal exchange numerically using ternary hybrid nanofluids (gold, copper, and alumina nanoparticles suspended in water) as the working fluid and investigates the coupled seepage and heat transfer behaviour of these through a single smooth fracture. A two-dimensional coupled thermo-hydraulic model using COMSOL Multiphysics 6.2 was developed, which solves the incompressible Navier-Stokes equations coupled with the heat equation. The parametric analysis investigates the effect of Reynolds number (Re=1–100), nanoparticle shape factor (n=3–8.9), total volume fraction (ϕ=1%–10%) and fracture width (F_w=0.5–3 mm) on the temperature distribution and the local Nusselt number. The outcomes show that convective cooling is significantly enhanced with the escalation of the Reynolds number, and the outlet temperature is prominently reduced by 41% as Re increases from 1 to 100, while the convection is simultaneously promoted to have about a 700% improvement in the local Nusselt number. On the other hand, the total volume fraction increase increases the fluid temperature up to 9% owing to the enhanced thermal conductivity, while the larger fracture widths decrease the local Nusselt number owing to the enhanced conductive heat loss.