Influence of turbulence parameters at supply inlet on room air diffusion.

Air flow conditions at the supply opening, which are used as boundary conditions in a numerical simulation, must be applied in order to proceed with the numerical solution of the air flow within a room. Among the conditions usually specified are the turbulence parameters, including the turbulence kinetic energy or the turbulence intensity and turbulent kinetic energy dissipation rate. Investigators have used a variety of expressions to estimate these quantities. A review of these expressions is presented in this paper. The focus of this paper is to assess the influence of prescribed turbulence intensity and turbulent kinetic energy dissipation rate at the supply diffuser on the computed air flow pattern, velocity, and turbulence intensity in the space served by the supply diffuser. The study indicates that the computed results converge to values corresponding to the measured values at a relatively faster rate when lower values of the turbulence intensity are used at the inlet boundary conditions, but that the final converged solution does not seem to be influenced by the value of the turbulence intensity for the range studied (4% to 37.4%). Also, computed results do not seem to be affected by the value of the inlet dissipation rate of the turbulence kinetic energy used at the inlet boundary conditions. In the cases studied, grid effects were negligible.