Analysis of laser beam deviation fluctuations in a turbulent nonisothermal flow and relevance to εθ

• Published in: International journal of heat and mass transfer 1995, Vol.38 (17), p.3135-3142
• Main Authors: El Ammouri, F., Soufiani, A., Taine, J.
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Physics; Turbulence simulation and modeling; Turbulent flows, convection, and heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/0017-9310(95)00084-M

The fluctuating displacements of a laser beam crossing a strongly nonisothermal channel air flow have been measured in the range [10 4-3.5 × 10 4] of the Reynolds number based on the hydraulic diameter. The measured instantaneous displacements are useful data for testing direct numerical simulations of nonisothermal turbulent flows. It is shown that the variances of these displacements are related to two-point correlation functions of temperature and temperature spatial derivatives. A first approach developed here to predict the beam displacement variances is based on a four supplementary equation, near-wall, turbulence model. These variances are shown to be related to components of the dissipation rate ε θ of temperature fluctuations. A satisfactory agreement between measured and predicted displacement variances is obtained.