Three-Dimensional Direct Numerical Simulation of Unsteady Transitional Round Fountains in a Homogeneous Fluid

Abstract:

Fountains are common both in nature and in industrial and environmental settings. These are jet flows with a negative buoyancy force acting in the direction opposite to the jet direction. The onset of asymmetry and unsteadiness, which occurs in transitional fountains with intermediate Reynolds (Re) and Froude (Fr) numbers, is the key to shed light on the turbulence generation mechanism in fountains. In this study, a series of three-dimensional direct numerical simulations are carried out for transitional round fountains with Re and Fr in the ranges of 1 ≤ Fr ≤ 8, 50 ≤ Re ≤ 500 to reveal their unsteady flow dynamics, in particular the onset of asymmetry, three-dimensionality, and unsteadiness. The numerical results show that the onset of asymmetry and unsteadiness can be detected and quantified by the tangent velocity on the interfacial surface between the fountain fluid and the ambient fluid. The results also demonstrate that a critical Re is at about 165 for Fr =2 fountains and is reduced to about 65 for Fr =3 fountains. Similarly, a critical Fr exists between 2 and 3 for the Re = 100 fountains, whereas for Re = 200 fountains it reduces to be between 1.8 and 2.

• Periodical: Applied Mechanics and Materials (Volume 553)
• Pages: 150-155
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.553.150
• Online since: May 2014
• Authors: Wen Xian Lin*, Tao Liu, Wen Feng Gao, Steven W. Armfield
• Keywords: Asymmetry, Direct Numerical Simulation, Transitional Round Fountain, Unsteadiness

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