EFFECT OF INCLINED ANGLE ON AIR BODY FORCE DURING AIR FLOW PROCESS INDUCED IN A RECTANGULAR BUILDING

Abstract

This study investigates the effect of inclined airflow angles on the air body force and its influence on buoyancy-driven ventilation in an un-stratified cross-ventilated rectangular domain with three openings. The airflow is primarily driven by the stack effect, where temperature differences between indoor and outdoor create density gradients, resulting in natural convection with an opposing flow introduced through one of the upper openings to mimic realistic ventilation input. The study focuses on three inlet airflow angles: 30°, 45°, and 55°, to assess their impact on temperature and velocity distribution within the domain. The system is modeled using a single-zone, one-dimensional approach, governed by steady-state Navier–Stokes equations. The equations are expressed in dimensionless form and solved using analytical method for ordinary differential equations (ODEs) to derive explicit solutions. Results show that lower airflow angles (e.g., 30°) enhance airflow momentum along the primary flow directions, intensifying convection and promoting faster air exchange, while higher angles (e.g., 55°) reduce airflow efficiency and flatten temperature gradients. The analysis also reveals that effective thermal coefficient impacts buoyancy force magnitude, altering the flow dynamics, and Prandtl number affects how fast heat moves compared to velocity, influencing stratification and mixing. The findings provide insight into optimizing natural ventilation design in buildings and support the development of energy-efficient, passive cooling strategies in architectural and engineering applications.