**Nomenclature**



#### **References**


25. Chen, C.-I.; Yang, Y.-T. Unsteady unidirectional flow of an Oldroyd-B fluid in a circular duct with different given volume flow rate conditions. *Heat Mass Transf.* **2004**, *40*, 203–209. [CrossRef]


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**Janusz T. Cie´sli ´nski**

Faculty of Mechanical and Ocean Engineering, Gda ´nsk University of Technology, Narutowicza 11/12, 80233 Gdansk, Poland; jcieslin@pg.edu.pl

**Abstract:** A comprehensive review of published works dealing with numerical modelling of forced convection heat transfer and hydrodynamics of nanofluids is presented. Due to the extensive literature, the review is limited to straight, smooth, circular tubes, as this is the basic geometry in shell-and-tube exchangers. Works on numerical modelling of forced convection in tubes are presented chronologically in the first part of the article. Particular attention was paid to the method of the solution of governing equations, geometry of the heating section, and boundary conditions assumed. Influence of nanoparticles on heat transfer and flow resistance are discussed. Basic information is summarized in tabular form, separately for single-phase approach and two-phase models. The second part of the article contains the correlation equations proposed in the presented papers for the calculation of the Nusselt (Nu) number or heat transfer coefficient, separately for laminar and turbulent flow. Details of the type of nanofluids, the concentration of nanoparticles, and the Reynolds (Re) number range are also presented. Finally, advantages and disadvantages of individual numerical approaches are discussed.

**Keywords:** forced convection; nanofluids; straight; smooth; round tubes; heat transfer; flow resistance
