Numerical heat transfer enhancement using different nanofluids flow through venturi and wavy tubes

In this study, the k-ϵ turbulence model with enhanced wall function using ANSYS commercial software is used for studying the effect of convergent/divergent sections on the heat transfer of nanofluids in two different cases. In first case, a venturi is modeled with different nanoparticles (SiO₂, Al₂O₃ and CuO) and in second case, a wavy tube with different sinusoidal wall functions (sin(x/2), sin(x) and sin (2x)) is considered. Results of first case revealed that SiO₂-water had the most surface Nusselt number among the other nanofluids and outcomes of second case confirmed that when the wave length is smaller (for sin (2x)) the temperatures near the walls increased and consequently the surface Nusselt number in peak areas are greater among other tested wall functions.