A TWO-EQUATION HEAT TRANSFER MODEL FOR WALL TURBULENT SHEAR FLOWS | ||||
| JES. Journal of Engineering Sciences | ||||
| Article 13, Volume 34, No 6, November and December 2006, Page 1877-1903 PDF (822.96 K) | ||||
| Document Type: Research Paper | ||||
| DOI: 10.21608/jesaun.2006.111184 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| M. S. Youssef* | ||||
| Mechanical Engineering Department, Faculty of Engineering, Assiut University, Assiut, Egypt. | ||||
| Abstract | ||||
| A proposal for closing the Reynolds-averaged energy equation is presented at the twoequation level of turbulence modeling. The eddy diffusivity for heat is proposed as a function of the local energy of turbulence, k, and the local temperature time scale, t , instead of using mixed time scale, m . The proposed two-equation heat transfer model solves two differential equations, one for the temperature variance, t k , and the other for the temperature time scale, t . The nearwall limiting behavior of turbulent quantities associated with heat transfer has been captured with the proposed model. Therefore, an additional term is included in the temperature variance equation to improve the prediction of nearwall behavior. Moreover, an exact and noval equation for the temperature time scale, t , is introduced in this study. The proposed t t k heat transfer model does not suffer from numerical stiffness problems since natural boundary conditions for the variables t k and t are used ( t k = t =0 at y=0). The proposed model is assessed by application to fullydeveloped turbulent channel flows under different wall thermal conditions with different values of Reynolds numbers. The results for all cases examined showed good agreement with those of the direct numerical simulation data. | ||||
| Keywords | ||||
| Turbulent Flow; k Model; kkL Model; t t k Model; FullyDeveloped Turbulent Channel Flow; Wall Thermal Conditions | ||||
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