Numerical investigation of mixed convection heat transfer of water-Fe3O4 nanofluid in a corrugated channel with moving walls

Abstract Increasing heat transfer in heat exchangers and ducts filled with various operating fluids for heat transfer is one of the main concerns of researchers and engineers in the energy conversion in the field of thermal engineering. Two examples of methods for increasing heat transfer in these ducts are the use of nanofluids instead of conventional fluids and the use of vortex generators in the fluid path or in the duct walls. In the present numerical study, the thermal performance of a water- $$F{e}_{3}{O}_{4}$$ F e 3 O 4 nanofluid is evaluated inside a two-dimensional channel with sinusoidal corrugated walls designed to promote vortex generation. In this regard, a steady heat flux from one and two walls was applied to the fluid and the wall was considered in two states, stationary and moving, and the effect of wall velocity, nanofluid mass flow rate, and transition time on the thermal parameters of the fluid between the two walls was investigated. Among the outstanding results obtained in this study, it can be noted that at lower velocities (between 0.01 and 0.1 m s –1 ), the temperature distribution in the channel is wider, meaning that more areas of the fluid inside the channel experience a temperature increase. The maximum temperature in the channel occurs in parts of it where the moving wall exits it, and increasing the velocity beyond 0.5 m s –1 no longer has a significant effect on the maximum temperature generated in the nanofluid. Overall, the findings indicate that adjusting the moving wall velocity alongside the nanoparticle concentration can considerably improve the thermal management of corrugated channels.