Rheology and electrokinetic flow of generalized Oldroyd-B fluids in two-layered vertical nanochannels: A numerical study with thermal and solutal coupling

This study examines the flow of a generalized Oldroyd-B fluid in a vertical two-layered nanochannel when an electric conduit is applied. The model considered magnetic fields, porous media, chemical interactions, solvent movement, and temperature effects. The finite difference methodology was used to resolve the system of equations obtained numerically. This innovative technique combines the flow of materials during expansion or compression with changes in fluid motion over time in a bilayer system, compensating for changes in physical properties and complex transfer patterns. The current research indicates that the power-law index, the Weissenberg number, and the bilayer structure significantly influence changes in temperature, speed, and concentration levels. Increasing the Weissenberg number results in higher electroosmotic velocities in thinner fluids when stretched due to their higher elasticity. It is also noted that the decrease in electroosmotic velocity due to the Weissenberg number is less pronounced in fluids with higher density when stirred. Furthermore, the combined buoyancy forces at and promote flow, providing valuable information on how to control nanofluidic systems as they flow vertically. This study thus identifies ways to improve electrokinetic transfer in various applications, including laboratory technology, smart chips, and membranes, as well as drug delivery.