Experimental and numerical study of a small-scale and low-velocity indoor diffuser for displacement ventilation: Isothermal floor

• Boundary conditions well posed in a small-scale experimental setup.
• Airflow patterns were recorded, finding good agreement with numerical simulations.
• Numerics allowed us to know convective heat transfer in the vicinity of the floor.
• Accurate correlations given: heat flux strongly depends on temperature difference.
• Accurate correlations given: heat flux weakly depends on flow rate.

The accurate knowledge of the dynamics and heat transfer of an attached cool radial jet in a laminar regime, discharging onto an isothermal floor and undisturbed atmosphere, is crucial to better control the parameters and reach a comfortable environment. In the present study, we first analyze a simple geometry of a small-scale, indoor displacement ventilation diffuser, by means of flow visualizations, and the PIV technique. In addition, we have carried out axisymmetric numerical simulations that show excellent agreement with qualitative and quantitative experimental data. Finally, we provide correlations of the heat flux as a function of non-dimensional parameters, finding out that the Nusselt number has a strong dependence on the Grashof number rather than the Reynolds number in this configuration. This simple model is a relevantly simple tool for practical engineering purposes such as the conditioning of large public areas with displacement ventilation systems.