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Experimental techniques against RANS method in a fully-developed turbulent pipe flow

Turbulence has been studied by scientists and engineers for decades as it appears in the majority of the fluids existent in nature and in engineering applications and because turbulent flow and its underlying behaviour are tremendously complex. The University of Manchester is widely viewed as the birthplace of turbulence due to the pioneering work of one of its prominent academics, Professor Osborne Reynolds (1842-1912). Building on this legacy, a classical experimental apparatus has been used in this paper to study a turbulent pipe flow with the aim of measuring the mean velocity field and wall shear stress using four experimental techniques, all developed in the 20th century, namely static pressure drop; mean square signals measured from a hot-wire; Preston tube; and the ‘Clauser Plot’. The experimental results have then been compared against those obtained using Computational Fluid Dynamics (CFD), utilising different two-equation turbulence models. The present work highlights the discrepancies evident in obtaining the value of the wall shear stress in each method. In addition, the scopes and limitations of each technique are discussed in detail, highlighting the clear evolution of turbulence study tools over the last 100 years.