Yen-De ChouWEI-SHIEN HWANGMaxim Solovchuk2025-05-172025-05-172025-03https://www.scopus.com/record/display.uri?eid=2-s2.0-85216898698&origin=recordpagehttps://scholars.lib.ntu.edu.tw/handle/123456789/729399Nanofluids are a new type of fluid designed to enhance heat transfer. Brownian motion is one of the key mechanisms by which nanofluids enhance heat transfer. In engineering applications involving double-diffusive convection, the temperature and concentration distributions on the surfaces of objects are often non-uniform. The aim of this study is to develop a fast solver to investigate: (1) the effects of non-uniform heating, non-uniform concentration, and Brownian motion on the heat and mass transfer in nanofluids within a three-dimensional n-shaped cavity, and (2) the effects of the composition and arrangement of multi-layer solids on the conjugate heat transfer. The results show that the multigrid method can accelerate the computations by a factor of 1000. Compared to uniform heating and uniform concentration, non-uniform heating and non-uniform concentration can enhance the heat transfer rate by 23.73% and the mass transfer rate by 28.04%. The heat transfer rate of the 5-layer solid is 6.91% higher than that of the 3-layer solid. This study provides important guidance for improving heat and mass transfer efficiency, with potential applications in cooling of electronic devices, solar collectors, and chemical reactors.Brownian motionConjugate heat transferDouble-diffusive convectionMultigrid methodNanofluidNon-uniform heating[SDGs]SDG7journal article10.1016/j.icheatmasstransfer.2025.108627