期刊
JOURNAL OF FLUID MECHANICS
卷 782, 期 -, 页码 333-355出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1017/jfm.2015.534
关键词
free shear layers; wakes/jets; plumes/thermals
资金
- Engineering and Physical Sciences Research Council (EPSRC) [EP/J500239/1]
- Engineering and Physical Sciences Research Council [1116239] Funding Source: researchfish
We discuss energetic restrictions on the entrainment coefficient a for axisymmetric jets and plumes. The resulting entrainment relation includes contributions from the mean flow, turbulence and pressure, fundamentally linking alpha to the production of turbulence kinetic energy, the plume Richardson number Ri and the profile coefficients associated with the shape of the buoyancy and velocity profiles. This entrainment relation generalises the work by Kaminski et al. (J. Fluid Mech., vol. 526, 2005, pp. 361-376) and Fox (J. Geophys. Res., vol. 75, 1970, pp. 6818-6835). The energetic viewpoint provides a unified framework with which to analyse the classical entrainment models implied by the plume theories of Morton et al. (Proc. R. Soc. Lond. A, vol. 234, 1955, pp. 1-23) and Priestley & Ball (Q. J. R. Meteorol. Soc., vol. 81, 1954, pp. 144-157). Data for pure jets and plumes in unstratified environments indicate that to first order the physics is captured by the Priestley and Ball entrainment model, implying that (1) the profile coefficient associated with the production of turbulence kinetic energy has approximately the same value for pure plumes and jets, (2) the value of a for a pure plume is roughly a factor of 5/3 larger than for a jet and (3) the enhanced entrainment coefficient in plumes is primarily associated with the behaviour of the mean flow and not with buoyancy-enhanced turbulence. Theoretical suggestions are made on how entrainment can be systematically studied by creating constant-Ri flows in a numerical simulation or laboratory experiment.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据