Pore-scale evaluation on hydrothermal performance in a microtube with homogeneous microporous media by lattice Boltzmann method

• Heat transfer and flow behavior of a laminar nanofluid microporous flow. • 3D Lattice Boltzmann Method was employed. • Inserting spherical objects as microporous media. • Microporous structure improves the heat transfer performance in the microtubes. • Undesirable impacts with lower number of spheres hence the larger spheres size. This study investigates the heat transfer and flow behavior of Al 2 O 3 -water nanofluids in micro-scale systems, using the lattice Boltzmann method (LBM) for numerical simulations. The research focuses on a three-dimensional microtube (500 μm diameter, 6000 μm length) subjected to a uniform wall heat flux, with Reynolds numbers between 40 and 100. Spherical particles of varying sizes and amounts are inserted into the flow path to examine the impact of porosity on thermophysical properties. The study also explores the relatively unexplored application of the LBM for curved boundaries. Results show that introducing 6–10 spherical objects at Re = 40 increases average Nusselt numbers by 23.61 % and 25.83 %, respectively, while larger spheres in smaller quantities had minimal or negative effects on heat transfer. The lattice Boltzmann method is gaining popularity in fluid dynamics, but its application to curved boundaries remains limited. This study advances the field by investigating flow dynamics in a microtube with spherical inserts, incorporating curved boundaries, nanofluids, and porous structures, which offers valuable insights into thermophysical studies.