Convective flows induced by HVAC (Heating, Ventilation and Air Conditioning) systems play an important role in the thermal comfort of buildings. However, they are particularly difficult to predict because they are not fully turbulent and interact with their environment.
In order to better predict and understand these complex flows, this contribution presents the validation of Large Eddy Simulations (LES)  of an axisymmetric and isothermal jet developing in a room near a wall. Although rarely used in building applications, mainly due to its high computational cost, LES provides more detailed and accurate predictions of interior flows compared to statistical models (RANS - Reynolds Averaged Navier-Stokes) . Moreover, this study is based on the Lattice-Boltzmann Method (LBM)  and the ProLB software . This framework allows for massively parallel computations and easy preprocessing of complex geometries. Therefore, the approach chosen allows to efficiently perform detailed and high-fidelity simulations of complex environments.
The simulations are validated and calibrated using an extensive experimental data set of a full-scale mechanically ventilated test room called MINIBAT . To this end, numerical results are compared with experimental data in terms of vertical and lateral jet expansion rates, mean velocity profiles within the jet and turbulent quantities. The results show a good qualitative and quantitative agreement between numerical and experimental data: the anisotropy of the jet expansion is well recovered and the shapes of the profiles as well as the maximum values of the mean velocity are consistent with experiment. Also, a qualitative analysis of the jet turbulence distribution is performed through the observation of Lumley triangles and the visualization of turbulent structures with vorticity contour plots. The analysis reveals that the main turbulent mechanisms in the jet development zone are well captured. Hence, the modelling approach adopted is suitable for the intended building application.
This work should be extended to anisothermal jet simulations to study thermal effects coupled with turbulence. It is also intended to couple the simulation of the hot jet with a high resolution building energy simulation . The coupling will enable more realistic dynamic boundary conditions at the room walls to evaluate the dynamics of heat transfers and thermal comfort.
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 F. Kuznik, “Etude expérimentale des jets axisymétriques anisothermes horizontaux se développant près d’une paroi: application à la modélisation numérique des cavités ventilées,” PhD Thesis, INSA, Lyon, 2005.
 T. Gresse, L. Merlier, J.-J. Roux and F. Kuznik, “Development of a 3D and high resolution dynamic thermal model of a room with sun patch evolution for thermal comfort applications,” Building Simulation Conference Proceedings, 2021.