Numerical Studies of Turbulence Effects in Cross-Flow Ventilation

Abstract

NUMERICAL STUDIES OF TURBULENCE EFFECTS IN CROSS-FLOW VENTILATION by Mina Mohammadmirzaei Natural ventilation systems reduce a building's utilization of energy in terms of electricity consumption and fossil fuel usage. Many factors including building shape, window style and configuration, and wind turbulence impact the efficacy of natural ventilation. In order to investigate the effect of turbulence on natural ventilation, twelve different conditions of a cross-flow ventilated room were studied numerically using computational fluid dynamics. Wind tunnel studies of tracer gases in a scale model were used to validate the numerical results. A comparison of twelve investigated cases shows that air circulation inside a natural ventilated room is only slightly affected by turbulence, and that the impact is strongest at low velocities. However, the result is small compared to the impact of wind velocity, and the relative impact of turbulence approaches zero at high velocities. Therefore, using fans to increase flow velocity results in better air replacement compared to using retrofitting geometries.

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“…Moreover, such system may reduce energy costs, thereby enabling the creation of sustainable cities (Kassim et al, 2016). The efficiency of natural ventilation is generally influenced by the building shape, window designs, and configuration and wind turbulence (Mohammadmirzaei, 2018). According to Bangalee et al (2014), outdoor fresh air may be drawn in to replace indoor air continuously through openings (i.e.…”

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“…In natural ventilation, fresh outside air is induced naturally by the temperature and pressure differences between spaces to replace the indoor air continuously through openings (vents, windows, doors and so forth) (Bangalee et al, 2014). Natural ventilation can either be wind-driven natural ventilation (cross ventilation) or buoyancy-driven natural ventilation (stack ventilation); the former attributed to pressure differences generated by the wind while the latter is caused by buoyancy forces (Mohammadmirzaei, 2018). Cross and stack ventilation may also co-occur, in which wind and stack effects could reinforce or oppose one another (Allocca et al, 2003).…”