3D Rayleigh-Benard-type natural convection in MWCNT-nanofluid-filled L-shaped enclosures with consideration of aggregation effect

Rayleigh-Benard type convective heat transfer in a 3D L-shaped enclosure filled with multiwalled carbon nanotube (MWCNT)-water nanofluids has been studied. The governing equations have been written using the vorticity-vector potential formalism and solved based on the finite volume method (FVM). The simulations were performed for various values of Rayleigh number, aspect ratio, and MWCNT volume fraction. The aggregation effect was considered, and the viscosity and thermal cavity were evaluated accordingly to fit with the experimental properties. The heat transfer is enhanced by increasing MWCNT volume fraction. The aspect ratio is found to be an optimization parameter of heat transfer especially for low Ra values. The aspect ratio equal to 0.4 provides the highest heat transfer for fraction nanofluid less than 3% and Ra number less than 10(5). Increasing the aspect ratio and fraction nanofluid enhances of the 3D character.