Numerical study of heat transfer in a 3D triangular prism with a rotating cylinder using ternary hybrid nanofluids and a new regression model

The rise in global temperatures has made it increasingly difficult to maintain a controlled indoor climate without excessive electrical energy consumption. Economic boundaries further strain the energy supply in many regions worldwide. This study investigates an innovative cooling application using ternary hybrid nanofluids (THNFs) in a roof structure modeled as a three-dimensional (3D) prism with an isosceles triangular base. A circular cylinder, capable of counterclockwise rotation, is integrated into the channel to enhance fluid dynamics. The cooling medium consists of water-based THNFs incorporating copper, aluminum oxide (alumina), and multi-walled carbon nanotubes. Numerical simulations of heat transfer and fluid flow are conducted using the non-isothermal flow interface in COMSOL Multiphysics 6.0, solving the three-dimensional Navier–Stokes and heat equations under realistic boundary conditions. Four key parameters, Reynolds number (100–500), nanomaterial shape factor (3–8.9), volume fraction of nanomaterials (1–10%), and cylinder rotational speed (0.1–0.4 m/s), are varied to assess their effects on heat distribution. The study evaluates average outlet temperature, Nusselt number, and Darcy-Weisbach friction factor.