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| Influences of inlet velocity ratio on coherent structures in planar jets |
| Revised:June 26, 2001 |
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| DOI：10.7511/jslx20032029 |
| KeyWord:planar jets,large eddy simulation,coherent structure |
| Liu Yi \ Guo Yincheng \ Zhang Huiqiang \ Wang Xilin \ Lin Wenyi |
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| Abstract: |
| Turbulent jet flow is the most widely used flow type in engineering applications. Most proportion of energy transportation and conversion processes is dominated by transient evolution of the large\|scale structures, or the coherent structures, in turbulent jets. In this paper, two\|dimensional spatial developing turbulent planar jets with different velocity ratios of jet fluid to co\|flow fluid at the inlet section are simulated with large eddy simulation approach in order to give detailed information of transient behaviors of coherent structures in turbulent jets and how the velocity ratios affect evolution of coherent structures. Transient distributions of velocity are obtained at different evolution periods of turbulent jets, and evolutions of coherent structures in flow field are also given. \;Filtered nondimensionalized governing equations are solved with standard Smagorinsky sub\|grid scale model, and transport equation of passive scalar is also solved in order to perform numerical visualization of flow field. Numerical simulation is performed by Chorin's fractional step method. Buneman variant of cyclic odd\|even reduction algorithm is adopted for solving pressure correction Poisson equation.\;Simulation results show structures of flow field at different velocity ratios and the transient evolution process of coherent structures in planar jets as well as the interaction between velocity ratio and coherent structures and explain the existence of the potential core region in turbulent jets. Results of this paper may provide basis for control and optimization of engineering applications associated with turbulent jet flows. |
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