Abstract
The global background of energy shortages and climate deterioration demands bioclimatic sustainable buildings. Vernacular architecture can provide a useful resource of passive strategies and techniques for creating inner comfort conditions with minimum heating, ventilation, and air conditioning (HVAC) assistance. The identification and verification of such knowledge are essential for climate responsive or energy passive building design. Among the methods, computational fluid dynamics (CFD) is a useful tool for simulating convective heat transfer of vernacular architecture and predicting the convective heat transfer coefficient (CHTC) and flow field. Geometric complexity and diversity of building samples are crucial in the development of an effective simulation methodology in terms of computational cost and accuracy. Therefore, this paper presents high-resolution 3D steady Reynolds-averaged Navier–Stokes (RANS) CFD simulations of convective heat transfer on Japanese vernacular architecture, namely, “machiya.” A CFD validation study on the CHTC is performed based on wind-tunnel experiments on a cube heated by constant heat flux and placed in a turbulent channel flow with a Reynolds number of 3.3 × 104. Three steady RANS models and two boundary layer modeling approaches are compared and discussed. Results show that the SST k-ω model applied with low Reynolds number modeling approach is suitable for CHTC simulations on a simplified building model. The RNG k-ε model applied with wall functions is an appropriate choice for simulating flow field of a complicated building model. Overall, this study develops a methodology involving RANS model selection, boundary layer modeling, and target model fitting to predict the convective heat transfer on vernacular architecture.
Highlights
40% of global energy is consumed in buildings [1], and 50% of building energy is used to maintain indoor comfort by utilizing heating, ventilation, and air conditioning (HVAC) auxiliary systems [2]
The main aim of the study presented in this paper is to seek an appropriate methodology for simulating the convective heat transfer in vernacular architecture considering computational cost and accuracy
For the top and lateral surfaces, considerable discrepancies are found in the value of convective heat transfer coefficient (CHTC), the SST k-ω and RNG k-ε models present a similar tendency to the experimental data
Summary
40% of global energy is consumed in buildings [1], and 50% of building energy is used to maintain indoor comfort by utilizing heating, ventilation, and air conditioning (HVAC) auxiliary systems [2]. The CHTC at the facade of a building is complex and influenced by a wide range of parameters, including building geometry [31], building surroundings [32], discrete measurement position on the building façades [17,18], facade roughness [33], wind speed, and wind direction [34,35] All these experiments and field measurements somehow have their shortcomings in terms of limited physical similarity regarding the flow pattern, architectural shapes and boundary conditions. The main aim of the study presented in this paper is to seek an appropriate methodology for simulating the convective heat transfer in vernacular architecture considering computational cost and accuracy.
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