CFD Apps - https://cfdapps.appspot.com - is a webbased portal for undertaking application specific Computational Fluid Dynamics (CFD) simulation. This presentation presents the recently released app that targets the simulation of wind in urban environment. The presentation covers the following subjects: - Why undertake a CFD study of urban wind environment? - How does the Urban Wind Study App work? - Two validation cases where the CFD Apps results are compared to experimental results; - A discussion of security aspects associated with the use of CFD Apps that users should be aware of.

1. CFD Apps, a Webportal for CFD
Modelling
Urban Wind Study Presentation

2. Presentation Outline
1.CFD Based Wind Study
2.CFD Apps

3. CFD Based Wind Study
Why simulating the wind
environment in urban
settings?
Pedestrian comfort
Pollution dispersion
Wind turbine
assessment

4. CFD Based Wind Study
• Pedestrian comfort:
• Evaluate the mean wind speed and
gust speed at pedestrian level;
• Compare predicted wind velocity to
benchmark(s).
Lawson Comfort Classification Mean Wind Velocity (m/s) Location
5 0-2 m/s Seating area
6 and 7 2-6 m/s Entrance to building
8 6-8 m/s Pedestrian footpath, public spaces
9 8-10 m/s Around building
10 10-12 m/s Roads and car park
Lawson criteria, taken from CFD Simulation of Wind Comfort and Safety in Urban Area: A Case Study of Coventry University Central
Campus, Fadl, M. and Karadelis, J., International Journal of Architecture, Engineering and Construction, June 2013

5. CFD Based Wind Study
• Setup up - Digital Model
Source: Feasibility Study for Establishment of Air Ventilation Assessment System, Department
of Architecture Chinese University of Hong Kong, November 2005

6. CFD Based Wind Study
• Setup up - Computational Domain Extent



7. CFD Based Wind Study
• Meshing
• Resolve geometrical features;
• Meet wall functions requirements - ie y+;
• Cost-effectiveness.
• Boundary Conditions
• Representation of neutral Atmospheric Boundary Layer
using:
– Log law; or
– Power law.

8. CFD Based Wind Study
• Guidelines:
• Feasibility Study for Establishment of Air Ventilation Assessment
System, Department of Architecture Chinese University of Hong
Kong, November 2005
http://www.pland.gov.hk/pland_en/p_study/comp_s/avas/papers&re
ports/final_report.pdf
• ERCOFTAC QNET-CFD Wiki
http://uriah.dedi.melbourne.co.uk/w/index.php/Civil_Construction_an
d_HVAC
• Guidebook for Practical Applications of CFD to Pedestrian Wind
Environment around Buildings, Architectural Institute of Japan
http://www.aij.or.jp/jpn/publish/cfdguide/index_e.htm
• SIG on "Quality and Trust in Industrial CFD", Best Practice Guidelines,
ERCOFTAC, January 2000
http://www.ercoftac.org/publications/ercoftac_best_practice_guidelines/singl
e-phase_flows_spf/

9. CFD Apps
URL: https://cfdapps.appspot.com

10. CFD Apps
openFoam setup
generation
Cost: Free
Analysis
Cost: AU$20 per scenario
• Solution based mesh refinement;
• Solver speed-up through use of multiple meshes;
• On the fly automated post-processing (basic).

11. CFD Apps
Submission confirmation
Select the analysis type

12. CFD Apps
Live demonstration
https://cfdapps.appspot.com

13. CFD Apps V&V
• AIJ Case D: A high-rise building in city blocks
View online results

14. CFD Apps V&V
• AIJ Case D: A high-rise
building in city blocks 1
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Average error:
• CFD vs Fiber probe: 0.6m/s
• CFD vs Thermintor: 0.8m/s
• Fiber probe vs Thermintor: 0.7m/s

15. CFD Apps V&V
• AIJ Case E: Building complexes with simple building shape (Niigata)
View before construction results
View after construction results

16. CFD Apps V&V
• AIJ Case E: Building complexes with simple
building shape (Niigata)
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Experimental CFD
Before Construction Vr = 0.343±0.129 Vr = 0.260±0.151
After Construction Vr = 0.421±0.163 Vr = 0.289±0.140
Velocity Ratio Results Averaged over 80 Test Locations

17. CFD Apps - Security
Security is lightweight to facilitate ease of use.
• Security relies on use of "complex" UUID and time limited storage
• Identification is through email address
no registration = no password
• Payment details are not kept on our server and are secure;
• Uploaded geometry is stored on secured cloud storage;
• Analysis result case is stored on secured cloud storage, but is
access through a time-limited public URL emailed to the user;
• Analysis result page is stored on a public URL for 30 days.

18. CFD Apps
Thank you
Question(s)?
Contact us at info@hibouscientificsoftware.com.au