332
K. B. Rajasekarababu and G. Vinayagamurthy
4 Conclusion
The purpose of this study is to assess and compare the wind flow features around
conventional (rectangle) tall building over un-conventional (taper and setback) buildings using IDDES turbulence model. The substantial recommendations of this study
derive the following conclusions.
• At y/H = 0.475, presence of setback on the building along with height shows
51% Cp reduction and just 16% for taper in comparison with rect building for the
leeward face. This is because the setbacks slow down the downstream.
• Dimensional changes along the height of the building showed a reduction of 70
and 90 percentage in Cp on the right side face of the taper and setback buildings
at y/H = 0.725. Moreover, there is a 54% and 82% reduction in Cp on the left
side faces of both the buildings, respectively.
• Instantaneous vortex structure indicates the formation of hairpin vortices with
high energy at downstream due to the driving and lagging vortices. Due to largely
expanded wakes, wake regions in the taper building was observed falling along
with the height.
• The features of trailing vortices of setback building differ from other buildings due
to downstream vortex breaks down, stretching of vortices reduced by the setbacks
and the intensity of the turbulence also reduces along with the height.
Overall, from this assessment, setbacks on building reduce the wind load and
ensure comfort compared with conventional tall buildings. Also, IDDES turbulence
model is possible to quantify the complex flow features in detail with limited grid
spacing.
References
1. Franke J (ed) (2007) Best practice guideline for the CFD simulation of flows in the urban
environment. Meteorological Inst
2. Franke J et al (2011) The COST 732 best practice guideline for CFD simulation of flows in the
urban environment: a summary. Int J Environ Pollut 44(1–4):419–427
3. Tominaga Y, Stathopoulos T (2010) Numerical simulation of dispersion around an isolated
cubic building: model evaluation of RANS and LES. Build Environ 45(10):2231–2239
4. Blocken B, Stathopoulos T, Carmeliet J (2007) CFD simulation of the atmospheric boundary
layer: wall function problems. Atmos Environ 41(2):238–252
5. Hang J et al (2012) The influence of building height variability on pollutant dispersion and
pedestrian ventilation in idealised high-rise urban areas. Build Environ 56:346–360
6. Janssen WD, Blocken B, van Hooff T (2014) Computational evaluation of pedestrian wind
comfort and wind safety around a high-rise building in an urban area
7. Liu J, Niu J (2016) CFD simulation of the wind environment around an isolated high-rise
building: an evaluation of SRANS, LES and DES models. Build Environ 96:91–106
8. Blocken B, Stathopoulos T, Van Beeck JPAJ (2016) Pedestrian-level wind conditions around
buildings: review of wind-tunnel and CFD techniques and their accuracy for wind comfort
assessment. Build Environ 100:50–81
K. B. Rajasekarababu and G. Vinayagamurthy
4 Conclusion
The purpose of this study is to assess and compare the wind flow features around
conventional (rectangle) tall building over un-conventional (taper and setback) buildings using IDDES turbulence model. The substantial recommendations of this study
derive the following conclusions.
• At y/H = 0.475, presence of setback on the building along with height shows
51% Cp reduction and just 16% for taper in comparison with rect building for the
leeward face. This is because the setbacks slow down the downstream.
• Dimensional changes along the height of the building showed a reduction of 70
and 90 percentage in Cp on the right side face of the taper and setback buildings
at y/H = 0.725. Moreover, there is a 54% and 82% reduction in Cp on the left
side faces of both the buildings, respectively.
• Instantaneous vortex structure indicates the formation of hairpin vortices with
high energy at downstream due to the driving and lagging vortices. Due to largely
expanded wakes, wake regions in the taper building was observed falling along
with the height.
• The features of trailing vortices of setback building differ from other buildings due
to downstream vortex breaks down, stretching of vortices reduced by the setbacks
and the intensity of the turbulence also reduces along with the height.
Overall, from this assessment, setbacks on building reduce the wind load and
ensure comfort compared with conventional tall buildings. Also, IDDES turbulence
model is possible to quantify the complex flow features in detail with limited grid
spacing.
References
1. Franke J (ed) (2007) Best practice guideline for the CFD simulation of flows in the urban
environment. Meteorological Inst
2. Franke J et al (2011) The COST 732 best practice guideline for CFD simulation of flows in the
urban environment: a summary. Int J Environ Pollut 44(1–4):419–427
3. Tominaga Y, Stathopoulos T (2010) Numerical simulation of dispersion around an isolated
cubic building: model evaluation of RANS and LES. Build Environ 45(10):2231–2239
4. Blocken B, Stathopoulos T, Carmeliet J (2007) CFD simulation of the atmospheric boundary
layer: wall function problems. Atmos Environ 41(2):238–252
5. Hang J et al (2012) The influence of building height variability on pollutant dispersion and
pedestrian ventilation in idealised high-rise urban areas. Build Environ 56:346–360
6. Janssen WD, Blocken B, van Hooff T (2014) Computational evaluation of pedestrian wind
comfort and wind safety around a high-rise building in an urban area
7. Liu J, Niu J (2016) CFD simulation of the wind environment around an isolated high-rise
building: an evaluation of SRANS, LES and DES models. Build Environ 96:91–106
8. Blocken B, Stathopoulos T, Van Beeck JPAJ (2016) Pedestrian-level wind conditions around
buildings: review of wind-tunnel and CFD techniques and their accuracy for wind comfort
assessment. Build Environ 100:50–81