Rezaei, AhmadrezaNiknejadi, MohammadrezaToghraie, DavoodSalahshour, Soheil2026-03-152026-03-1520262214-157X10.1016/j.csite.2026.107706https://doi.org/10.1016/j.csite.2026.107706https://hdl.handle.net/20.500.14517/8914This study explores the effects of nanofluids, used as a dense discrete two-phase system with nanoparticle volume fractions (phi) ranging from 0 to 3 %, on heat transfer in a ribbed micro-channel with a porous medium. Key parameters such as rib angle, Darcy number, and Reynolds number were analyzed for their effect on heat transfer and particle migration. Results indicate that increasing the Darcy number from 0 to 1.883e-4 at a 30 degrees angle and phi = 3 % raised the Nusselt number from 1.8235 to 2.0376 while increasing the Reynolds number from 10 to 1000 at a 30 degrees angle and the same phi raised the Nusselt number from 2.1030 to 3.7519. The maximum Nusselt number observed was 3.9047 for a microchannel with 90 degrees ribs, Reynolds number of Re = 1000, phi = 3 %, and a Darcy number of 7.533e-4. Conversely, the results show that increasing the phi also increases fluid density and relative viscosity, leading to higher kinetic energy and maximum flow velocity in the microchannel. Finally, the results revealed that in the presence of a porous medium with a Darcy number of 1.883e-4, for micro-ribs with an angle of 90 degrees, Re = 10, and phi = 1 %, the value of the friction factor increases from 0.5956 to 0.9495.eninfo:eu-repo/semantics/openAccessHeat TransferMicrochannelsNanofluidsOptimizationNusselt NumberDarcy NumberArticle