This paper studies hydrodynamic and heat transfer performance of Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe in laminar flow regime using the computational fluid dynamic approach. A parametric study was carried out on the effect of Reynolds number (300– 1200), convergence index (0-3) and nanoparticle concentration (0–3%) on the both hydrodynamic and thermal fields. The results showed the pressure drop profile along the axial length of the converging pipes is parabolic compared to the downward straight profile obtained in a straight pipe. Furthermore, an increase in convergence index, Reynolds number and nanoparticle concentration were found to enhance convective heat transfer performance. Also, a new empirical model was developed to estimates the average Nusselt number as a function of aforementioned variables. Finally, the result of the thermohydraulic performance evaluation criterion showed that the usage of Bessel-like converging pipes is advantageous at a low Reynolds number.

In the presented paper, two different meshing strategies are compared to show the accuracy advantage of properly constructed mesh. For this purpose, it was necessary to automatize simulation process, in order to perform a number of calculations without the necessity of user interaction. Later, a method of results extrapolation as well as a way of judging mesh quality are introduced for more throughout comparison of presented discretization strategies. The latter method, called grid convergence index, is also used to calculate probability range of accurate result. To conclude, outcomes of this study are in agreement with general opinon on pracitces for an accurate CFD result. Structured O-type mesh with refinement at wall boundaries (often referred to as “inflation layers”) performs better than simple free mesh.