Unsteady CFD Simulation in a Naturally Ventilated Room with a Localized Heat Source

Abstract

This study examines the temperature distribution and the flow field in a naturally ventilated room with a localized floor heat source. The room has an orthogonal form with a low and a high opening placed in opposite walls. The temperature of outdoor air is cooler than the initial indoor air temperature forming buoyancy-driven natural ventilation (with U_wind≈0). The problem is explored with computational simulation using a CFD software. A model validation is presented with experimental and computational results of previous investigation^10,11 on natural ventilation including buoyancy forces. The 3D unsteady Reynolds Averaged Navier Stokes (RANS) equations are solved in conjunction with the energy equation and the turbulence RNG k-ɛmodel. The unsteady flow of natural ventilation with buoyancy forces is analyzed andthe vertical variation of temperature with respect to timeis investigated. A thermal stratification is formed which is justified by the respective indoor air movement. The upper buoyant layer is warmer than the bottom one, while the indoor air temperature of both layers increases with time. A thermal comfort exploration accompanies the outcoming results and provides useful information for similar problems. Finally, a number of conclusions are derived about the simulation process, the function of natural ventilation and the thermal comfort of the space in corresponding cases.