## Influence of the thermal and RANS closures on walls heat transfers computations

### ECOS 2017

**Abstract :**

This study deals with the heat transfers calculations between the internal walls of a duct and a

non-isothermal turbulent flow inside this later on. The departure point for this work is the appearance

of an asymmetry in the velocity fields, implying consequently a modification of the temperature profiles

[1, 2]. Therefore, the fluid properties can be modified and the corresponding Reynolds numbers and \(y^+\)

values can be significantly different from one side to another. We will first present the fluid and thermal

modeling retained, using both an EB-RSM model with thermal GGDH closure and a \(k-\varepsilon- v^2/k\)

model, i.e. two elliptic models either at order two or order one. Then, the heat transfers at the walls

are computed on a 3D geometry consisting of a T–junction between a cylindrical pipe and a larger

rectangular duct, whose flow are turbulent yet with different velocities. This type of devices corresponds

usually to a part of a larger one involved in nuclear power plants.

**Keywords :** RANS, EB-RSM, \(k-\varepsilon- v^2/k\), thermal modeling, GGDH, wall heat transfers

[1] Sylvain Serra, Adrien Toutant, Françoise Bataille, and Ye Zhou. High-temperature gradient effect on a turbulent channel flow using thermal large-eddy simulation in physical and spectral spaces. Journal of Turbulence, 13 :1–25, 2012.

[2] Sylvain Serra, Adrien Toutant, and Franc¸oise Bataille. Thermal large eddy simulation in a very simplified geometry of a solar receiver. Heat Transfer Engineering, 33(6) :505–524, 2012.