Rayleigh–Benard Convection of Carbopol Yield Stress Fe3O4 Nanofluids Under Magnetic Field: An Experimental Investigation and ANN Modelling

This study presents a comprehensive experimental investigation aimed at elucidating the influence of magnetic fields, nanoparticle concentration, and the presence of polymer on Rayleigh–Benard convection in yield stress nanofluids. The test fluid comprises Ultrez 30 polymeric powder and Iron oxide nanoparticles. Herschel–Bulkley's model is applied to capture the rheological behaviour. The concentration of both Ultrez 30 polymeric gel and Iron oxide nanoparticles varies from 0.05 % to 0.10 %. The in-house developed experimental set-up is exposed to the magnetic field in the 0 mT to 100 mT range. Without a magnetic field, heat transfer increases with the elevation of nanoparticle fraction in the fluid. However, in the presence of a magnetic field, the convection effect weakens as the nanoparticle concentration rises. Furthermore, an optimised artificial neural network (ANN) model featuring a single hidden layer with nine hidden neurons is presented to predict the Nusselt number.