Topic
Pipe flow
About: Pipe flow is a research topic. Over the lifetime, 13826 publications have been published within this topic receiving 351605 citations.
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TL;DR: In this article, the general problem of air entrainment by flowing water in pipes, particularly in reference to the removal of air pockets from water supply lines, was treated, and the formation of air pocket was investigated.
Abstract: The general problem treated in this paper is the study of air entrainment by flowing water in pipes, particularly in reference to the removal of air pockets from water supply lines. The formation o...
93 citations
TL;DR: The critical peak Reynolds number was found to correlate with the Womersley parameter and the Strouhal number as a power law function with a root-mean-square (rms) error of 15.2%.
Abstract: An empirical correlation for the onset of turbulence in physiological pulsatile flow is presented. We pumped three different test fluids of kinematic viscosity 0.008–0.035 cm2/s through four straight tubes 0.4–3.0 cm in diameter. A Scotch yoke mechanism provided an oscillatory sine wave flow component of known stroke volume and frequency. We adjusted the mean flow independently until we detected signal instabilities from hot film wall shear stress probes. The critical peak Reynolds number was found to correlate with the Womersley parameter and the Strouhal number as a power law function with a root-mean-square (rms) error of 15.2%. Experimental measurements of the laminar velocity profile are compared to theoretical predictions from Poiseuille’s law and Womersley’s solution.
93 citations
TL;DR: It is found that turbulence becomes sustained at a distinct critical point once the spatial proliferation outweighs the inherent decaying process and scale invariance at the onset of turbulence is demonstrated.
Abstract: Laminar-turbulent intermittency is intrinsic to the transitional regime of a wide range of fluid flows including pipe, channel, boundary layer, and Couette flow. In the latter turbulent spots can grow and form continuous stripes, yet in the stripe-normal direction they remain interspersed by laminar fluid. We carry out direct numerical simulations in a long narrow domain and observe that individual turbulent stripes are transient. In agreement with recent observations in pipe flow, we find that turbulence becomes sustained at a distinct critical point once the spatial proliferation outweighs the inherent decaying process. By resolving the asymptotic size distributions close to criticality we can for the first time demonstrate scale invariance at the onset of turbulence.
93 citations
TL;DR: In this article, a study of a porous block mounted on a heated wall in a laminar flow channel to enhance convection heat transfer rate was investigated numerically, and the effects of the above parameters on the thermal performance of the heated wall were examined in detail.
93 citations
TL;DR: In this paper, the authors proposed a non-linear eddy-viscosity model with tensorial terms, alongside strain and vorticity, which depend on wall-direction indicators and procure the correct asymptotic near-wall behavior of the Reynolds stresses.
93 citations