Heat transfer enhancement and flow characteristics past trapezoidal bluff body embedded in unconfined cavity filled with nanofluid

A numerical study has been carried out to investigate the forced convective flow around a trapezoidal cylinder exposed to a uniform stream of nanofluid. Water-based nanofluid containing various types of nanoparticles $(\rm Al_2\rm O_3{,}~\rm Cu{,}$ and $\rm CuO)$ with the solid volume fraction $\varphi$ varying from $0$ to $8\%$ were used to examine the fluid flow and potential heat transfer enhancement from the heated cylinder. Computations based on the finite volume method with SIMPLE algorithm have been carried out at the steady laminar flow regime with a Peclet number range of $25 \le \rm Pe \le 150$. Nanofluids flow and heat transfer characteristics are found to be highly dependent on solid volume fraction, Peclet number, and nanoparticles shapes. Enhanced wake lengths and surface vorticity, reduced drag and higher heat transfer rates are seen in nanofluids. Furthermore, the results reveal that one type of nanoparticle is a key factor for improving some engineering parameters. In particular, the height values of the average Nusselt number $\rm Nu_{av}$, the maximal surface vorticity $\omega_{s{,}~\text{max}}$, and the dimensionless wake length $L_r$ are obtained while using $\rm Cu$ nanoparticles. However, the values of the drag coefficient $C_D$ are higher for $\rm Al_2\rm O_3$ nanoparticles. Eventually, reliable correlations for $\omega_{s{,}~\text{max}}{,}~C_D{,}$ and $\rm Nu_{av}$ in terms of $\varphi$ and $\rm Pe$ have been developed throughout this study.