| 1. |
40450 A study on wind tunnel experiment for modeling of the bulk scalar transfer coefficients of complex urban array : Part 2 Result on roughness with non-uniform heights. |
| 2. |
41389 Large-eddy simulation on scalar transfer phenomena between urban surface and atmosphere. |
| 3. |
40334 A study on the similarity between a momentum and scalar roughness length based on scalar profile measurements by means of wind tunnel experiments.. |
| 4. |
41366 Statistical analysis on low speed streaks organized above urban-like arrays. |
| 5. |
41365 A study on the effects of different aspect-ratio blocks on the form drag by using wind tunnel experiments. |
| 6. |
Sato Tsuyoshi, Hagishima Aya, Ikegaya Naoki, Tanimoto Jun, Particle Image Velocimetry Measurement of Unsteady Turbulent Flow around Regularly Arranged High-Rise Building Models, International Journal of High-Rise Buildings, 2, 2, 105-113, 2013.06, Recent studies proved turbulent flow properties in high-rise building models differ from those in low-rise building models by comparing turbulent statistics. Although it is important to understand the flow characteristics within and above high-rise building models in the study of urban environment, it is still unknown and under investigation. For this reason, we performed wind tunnel experiment using Particle Image Velocimetry (PIV) to investigate and identify the turbulent flow properties and characteristic flow patterns in high-rise building models. In particular, we focus on instantaneous flow field near the canopy and extracted flow field when homogeneous flow field were observed. As a result, six characteristic flow patterns were identified and the relationship between these flow patterns and turbulent organized structure were shown.. |
| 7. |
41388 Analysis on optimization for the aerodynamic parameters of urban-like rough surfaces.. |
| 8. |
41382 Particle Image Velocimetry Measurement of Unsteady Turbulent Flow around Regularly Arranged High-Rise Building Models. |
| 9. |
41315 A study on similarity of profiles between velocity and scalar concentration in an urban boundary layer. |
| 10. |
41361 Effects of heterogeneity of scalar source distribution and roughness on scalar transfer coefficients of urban surfaces : Part 2 Effect of scalar source size on scalar transfer coefficient and scalar roughness length. |
| 11. |
41360 Effects of heterogeneity of scalar source distribution and roughness on scalar transfer coefficients of urban surfaces : Part 1. Experimental setting and measured transfer coefficients. |
| 12. |
41358 Particle Image Velocimetry Measurement of Unsteady Turbulent : Flow around Regularly Arranged High-Rise Building Models. |
| 13. |
41336 Numerical study on the effect of turbulent field generated by simple cubical arrays on the wall pressure. |
| 14. |
40409 A study on the probability characteristics of occupant behavior for using air-conditioner in residential buildings. |
| 15. |
Statistical Analysis of Time-Series Data of Electricity Consumption of Air Conditioners Observed in Multiple Dwellings. |
| 16. |
C. HIROSE, N. IKEGAYA, A. HAGISHIMA, J. TANIMOTO, Computational Fluid Dynamics for Cross-Ventilated Airflow in an Urban Building, Japan Architectural Review, 10.1002/2475-8876.12312, 00, 1-9, 2022.11, In this study, the velocity field in a naturally ventilated building within an urban-like array was explored using large-eddy simulations. Reduced-scale building models were used to examine the impacts of the geometric conditions in the surrounding buildings and cross-ventilating windows on the flow statistics and instantaneous velocity fields in the sheltered building. The instantaneous velocity components averaged in the opening area were calculated for each condition of the building arrays and openings. The results indicate that the surrounding urban geometry significantly affects the turbulent opening velocities. Additionally, the three-dimensional instantaneous velocity distributions within the target building clearly demonstrate considerable differences under the different building and opening conditions. Such differences also affect the mean, maximum, and minimum wind speeds within the indoor regions. Moreover, the distributions of the two-point correlation coefficient (defined by the velocities normal to the windows at the center of the windward opening and inside the building) were compared for each condition. The strong correlations near the two openings indicate that the instantaneous velocity generated by the surrounding buildings is an important factor in determining the statistical and instantaneous features of indoor ventilating airflows.. |
| 17. |
C. Hirose, T. Nomichi, N. Ikegaya, Distributions of gust and peak factors at a pedestrian level in a simplified urban canopy obtained by particle image velocimetry, Building and Environment, 10.1016/j.buildenv.2022.109350, 222, 2022.08. |
| 18. |
EFFECT OF MOMENTUM PROVISION IN COMPUTATIONAL FLUID DYNAMICS ON TURBULENT STATISTICS IN URBAN BOUNDARY LAYER
To reproduce homogeneous flow fields above urban-like turbulent boundary layers in computational fluid dynamics (CFD), numerous CFDs with a limited numerical domain employ periodic boundary conditions in both lateral directions with artificial momentum provision to maintain airflows. Although such artificial momentum sources are clearly different from the momentum provision in windtunnel experiments, the effects of these numerical conditions on the airflow in the boundary layer are not well studied. In this paper, therefore, we investigate how the momentum provision differentiates the vertical Reynolds stress and turbulent kinetic energy profiles using large-eddy simulations of airflows over cubical block arrays.. |
| 19. |
COMPUTATIONAL FLUID DYNAMICS for CROSS-VENTILATED AIRFLOW in AN URBAN BUILDING
The velocity field in a naturally ventilated building within urban-like arrays was explored by means of large-eddy simulations. The reduced-scale building models were utilized to examine the impact of the geometric conditions in surrounding buildings and cross-ventilating windows on flow statistics as well as instantaneous velocity fields in a sheltered building. The obtained results indicated how the incoming flow was propagated in the target building. Although simplified conditions were employed, the present findings of the features of cross-ventilation are valuable to consider the effect of outdoor turbulent flow to indoor wind environment.. |
| 20. |
Statistical Analysis of Time-Series Data of Electricity Consumption of Air Conditioners Observed in Multiple Dwellings. |
| 21. |
Rahnat Nurizzatul Atikha, Hagishima Aya, Ikegaya Naoki, Tanimoto Jun, Omar Abd Rahman, An experimental study on aerodynamic interaction between a boundary layer generated by a smooth and rough wall and a wake behind a spire, 九州大学大学院総合理工学報告, 10.15017/1560669, 37, 2, 19-26, 2016.02, A wind tunnel experiment to assess the flow characteristics of the wake behind a spire mounted normal to the wind tunnel floor was conducted to clarify the interaction between the wake flow and the wall shear boundary layer. To reproduce the contrasting boundary layer depth, two types of walls-a smooth wall and a regular cube array-were adopted; for each wall, the spanwise distribution of the streamwise velocity was measured at two downwind positions and seven heights within and above the wall boundary layer with and without a spire. The span wise distribution of the wake generated by the spire far above the wall boundary layer with low turbulence agreed with the well-known function for two-dimensional (2D) wake flow, derived theoretically from the gradient-diffusion model, despite the weak asymmetry of the inflow. In contrast, the spanwise distribution of the wake within or near the outer edge of the wall boundary layer showed different trends from that of the 2D wake flow. In the former, the expansion of the wake width is compressed in the lateral direction by the turbulence of the wall boundary layer and the velocity deficit of the wake is sustained far from the spire.. |
| 22. |
Mohamad Mohd Faizal, Hagishima Aya, Ikegaya Naoki, Tanimoto Jun, Omar Abd Rahman, Aerodynamic effect of overhang on a turbulent flow field within a two-dimensional street canyon, 九州大学大学院総合理工学報告, 10.15017/1525830, 37, 1, 1-7, 2015.09, This paper reports the results of flow field analysis within and above a two-dimensional street canyon with various overhang lengths using large-eddy simulation (LES). Simulations were conducted for a constant canyon aspect ratio of W/H = 3, where W is the street width and H is the building height. Three different overhang lengths were simulated with P = 0H, 0.5H, and 1H in order to derive the mean and instantaneous flow characteristics. The results are compared with wind tunnel experiments for validation. The LES results of the mean flow with the P = 0H condition agree fairly well with the wind tunnel data. However, profiles of the standard deviation for the streamwise and vertical velocity components show large discrepancies at all measured locations. In addition, an increase in overhang length on both building façades significantly modifies the in-canyon flow pattern by limiting the penetration of the bulk flow into the canyon layer.. |
| 23. |
Sato Tsuyoshi, Hagishima Aya, Ikegaya Naoki, Tanimoto Jun, Particle Image Velocimetry Measurement of Unsteady Turbulent Flow around Regularly Arranged High-Rise Building Models, International Journal of High-Rise Buildings, 2, 2, 105-113, 2013.06, Recent studies proved turbulent flow properties in high-rise building models differ from those in low-rise building models by comparing turbulent statistics. Although it is important to understand the flow characteristics within and above high-rise building models in the study of urban environment, it is still unknown and under investigation. For this reason, we performed wind tunnel experiment using Particle Image Velocimetry (PIV) to investigate and identify the turbulent flow properties and characteristic flow patterns in high-rise building models. In particular, we focus on instantaneous flow field near the canopy and extracted flow field when homogeneous flow field were observed. As a result, six characteristic flow patterns were identified and the relationship between these flow patterns and turbulent organized structure were shown.. |
