Brief Discussion on the submitted posters to PRAGMA 18, and AD for PRAGMA 20 Computer Centre

1. Brief Discussion on the submitted posters to PRAGMA 18, and AD for PRAGMA 20 Computer Centre W.K. Kwan (kwk@cc.hku.hk) 5th March 2010

2. Agenda • Submitted posters to PRAGMA 18 • Brief discussion on that of Geosciences • Brief discussion on that of Telesciences • HPC / Grid Computing facilities in HKU • Call of collaboration • PRAGMA 20 to be hosted by HKU in March 2011

3. 8 posters submitted in PRAGMA 18 • All from our HKU HPC users

4. Geosciences (Civil Engin.) • Dr. Ji Chen • Investigation of Urban Land Use Change and Anthropogenic Heat Effect on Temperature Change by WRF Model in Guangzhou-Shenzhen, South China • (previous work from the same group) • Large-scale Water Resources Management • Effects of land surface change on regional hydrologic cycle • River flow modeling of the Mekong River Basin

5. Geosciences (Mech. Engin.) • Heat Loss from Street Canyons • Large-Eddy simulation of Pollutant Plume Dispersion in the Urban • Canopy Layer over 2D Idealized Street Canyons • Large-Eddy Simulation of Natural Ventilation in Urban Environment • Large-Eddy Simulation of Pollutant Removal in Neutrally & Unstably stratified Street Canyons

6. Computational Solution to Air Pollution Physics & Chemistry in Dense & Compact Cities W.C. Cheng, James O.P. Cheung, Tracy N.H. Chung, Chun-Ho Liu & Colman C.C. Wong Department of Mechanical Engineering, The University of Hong Kong Lilian Y.L. Chan, Frankie F.T. Cheung & W.K. Kwan Computer Centre, The University of Hong Kong

7. Core Research Interests with applications for dense & compact cities Air pollution physics & chemistry Geophysical turbulence Scientific computing

8. Major Materials Reported to PRAGMA18 Air pollution physics & chemistry in urban areas are studied by computation fluid dynamics (CFD) • Large-eddy simulation (LES) Open-source CFD code OpenFOAM-15 or -16 OpenMPI or MPICH for inter-processor comm. HPCPOWER2 Linux cluster of the Computer Centre, the University of Hong Kong • 24 blades 64-bit dual quadcore 3 GHz Xeon • 2.3 Tera-FLOPS (Theoretical Rpeak) Extending to GRIDPOINT • 128 blades 64-bit dual quadcore 2.53 GHz Nehalem • 10.3 Tera-FLOPS (Theoretical Rpeak)

9. Large-Eddy Simulation of Ventilation & Pollutant Removal in Neutrally & Unstably Stratified Street Canyons Background & Objective Buoyancy-driven flows are commonly found in the daytime atmospheric boundary layer (ABL) CFD LES was used to examine their contributions to the ventilation & pollutant removal in urban street canyons Major Findings Higher wind speed & turbulent kinetic energy (TKE) are found in unstable stratification Pollutant plume is a shallow layer over the street canyons in neutral stratification but is carried rapidly upward into the ABL in unstable stratification Solar irradiation in the daytime ABL enhances pollutant removal from urban areas

10. Pollutant removal in neutral stratification Pollutant removal in unstable stratification More rapid pollutant plume rise in unstable stratification

11. Natural Ventilation in the Urban Environment Background & Objective Natural ventilation is influenced by building envelope in our modern environments Natural ventilation behavior in low-rise structures was examined using CFD LES Major Findings Recirculating flow in front of the windward opening Turbulence intensities can be promoted by 50% at the openings Ventilation mechanism changes noticeably once neighboring buildings are included A vast fresh air entrainment is observed on the windward roof level Reverse flow is occasionally observed at small building separation

12. Fresh air entrainment Occasional Reverse flow

13. Heat Loss from Street Canyons Background & Objective Heat loss from buildings to the surrounding is undesirable in wintertime due to the excessive energy consumption CFD LES was used to compare the local heat transfer coefficient in the street canyons of different aspect ratios Major Findings Only 1 primary recirculation is found in the wake interference regime (h/b = 1/4) Persistent flow reattachment & separation are found in the isolated roughness regime (h/b = 1/11) Maximum & minimum of local heat transfer coefficients coincide with the reattachment & separation points, respectively, on the street

14. Street Canyon flow in the skimming flow regime h/b = 1/4 – Spatial contours of temperature Prevalent wind More heat loss on the windward side

15. Large‐Eddy Simulation of Pollutant Plume Dispersion in the Urban Canopy Layer over 2D Idealized Street Canyons Background & Objective Gaussian pollutant plume model has been widely used in the estimation of air pollutant distribution in the ABL CFD LES was used to examine the necessary modifications when the Gaussian plume model is applied in the urban canopy layer (UCL) Major Findings Dispersion coefficient in the UCL follows the Gaussian-plume shape in general Roof-level pollutant concentration is largely affected by the air entrainment / pollutant removal for the street canyons that differs from the Gaussian plume model markedly

16. Non-Guassian plume shape Fresh air entrainment

17. Upcoming Work Higher Spatio-temporal Resolution Use more refined/accurate CFD LESs to study the flow & pollutant transport especially the roles of small/transient turbulence scales Multi-scale Coupling Use multi-block CFD LESs model to study the coupling among different length/time scales How large-scale atmospheric turbulence affects (purges) pollutants in street canyons at the bottom of the ABL Chemistry & Micro-physics Study the transport of chemically reactive air pollutants Study the condensation/evaporation/phase-change of air pollutants Comparison with Field Measurements Use latent heat/telescience/satellite images from the PRAGMA community to validate our CFD LES

18. Incorporation of satellite data (thanks to PRAGMA)

19. The University of Hong Kong

20. The University of Hong Kong • Founded in 1912 • Ranked 18th in "THES-QS World University Rankings 2007” • Ranked 1st in “QS.com Asian University Rankings 2009” • 12,300 undergraduate students • 9,900 postgraduate students • 10 faculties • Architecture, Arts, Business and Economics, Dentistry, Education, Engineering, Law, Medicine, Science, Social Sciences (a comprehensive University)

21. Central HPC Facility Advancement • Year Top500 System Rmax Rpeak • 2009 --- System for HKU Grid Point (around 18000) • 2008 --- 192-Cores + 356-CPU 2376.3 4337.6 IBM Linux Cluster • 2005 --- 356-CPU IBM Linux Cluster 1086.19 2033.6 • 2003 240t h 256-CPU IBM Linux Cluster 637.8 1433.6 • 2001 --- 64-CPU HP Linux Cluster --- 64.0 • 2000 --- 8-CPU Linux Cluster --- 12.8 • 1998 345th 48-CPU IBM SP2 22.2 30.7 • 1995 186th 32-CPU IBM SP2 6.6 8.5 • 1993 --- 8-CPU IBM SP1 --- 1.0

22. Central HPC Services at HKU • Support intensive computation for cutting-edge researches in the university • Deploy high performance and large scale computing facilities, and the latest software technology • User training and consultation

23. Our projects and researchers http://www.hku.hk/cc/ccsystem/hkuhpcc/

24. HKU is not rich in computing facilities, but strong in experience and researchers

25. Grid computing activities of HKU

26. HKU has joined many High-speed Research Networks HKU is at present a member of CNGrid, TWGrid, PRAGMA and APGrid PMA (due to HK’s special geographical and “political” position), and intends to further the development to establish a HKGrid through the HKU Grid Point development

27. Experience in multi-institutional / grid related activities: High-speed Research Network HARNET Internet2 China Science and Technology Network (CSTnet) Trans-Eurasia Information Network (TEIN2) Korea Research Environment Open Network (KREONET) CERNET (China Education and Research Network)

28. Grid Computing – Development & Collaborations Local HPC clusters Campus Grid Regional Grid (HK Grid) National Grid (CN Grid) International Grid (EGEE, APGrid, PRAGMA)

29. China National Grid

30. CNGRID HKU is A Grid Point of CNGrid (China National Grid) since 2005 (the only one outside China mainland) Many HKU researchers have research collaboration with China parties Many projects in CNGRID (863) are of national scale

31. 中国国家网格2008学术年会12月18-20日召开上海超级计算中心·张江·上海中国国家网格2008学术年会12月18-20日召开上海超级计算中心·张江·上海 • An afternoon agenda: 13：30—13：50 宝钢公司：樊俊飞：CFD技术在宝钢的应用 13：50—14：10 上海核工院：谢永城：高性能仿真平台在核电站设备分析法设计中的应用 14：10—14：30 上海飞机设计研究所：张淼：大型客机气动设计问题 14：30—14：50 上海708研究所：王金宝：CFD技术在船舶设计中的应用 14：50—15：10 上海交通大学空天学院：刘洪：飞机设计大平台介绍 15：30—15：50 Simulia 公司：高尚武：ABAQUS最新发展技术 15：50—16：10 上海交通大学船舶与建筑工程学院：尤云祥：高性能计算在船舶与海洋工程中的应用 16：10—16：30 上海交通大学CIMS研究所：范秀敏：基于网格的协同虚拟装配 16：30—16：50 铁道部信息技术中心：邢智民：中国铁路网格货运信息综合应用系统研究与实现 16：50—17：10 中科院计算所：邹永强：基于中国国家网格的高性能计算环境

32. PRAGMA • Pacific Rim Application and Grid Middleware Assembly (PRAGMA) • A platform to report on the progress from focused working groups and also a venue to involve new collaborators in PRAGMA activities • PRAMGA Workshop meets twice a year • HKU accepted as institutional member in PRAGMA 16 (March 23-25, 2009) • At the moment, HKU is the only PRAGMA institutional member in HKSAR, and also the only institutional member in the southern part of Yangtze River in China.

33. PRAGMA

34. EGEE • Enabling Grids for E-sciencE • the largest multi-disciplinary grid infrastructure in the world • more than 140 institutions, about 300 sites in 50 countries • Currently already EGEE-III, co-funded by the European Commission

35. EGEE (2) • Centralized Grid research/operation consortium in Europe • Taiwan Academia Sinica Grid Computing (ASGC) invited in December 2005 to become the major Regional Operation Centre (ROC) in Asia • HKU CC Setup of EGEE (Enabling Grids for E-sciencE) Grid testbed at 2007, becomes site member of TWGrid VO

36. Certificate Authority • All grid sites and users require digital certificates for authentication • Now proposing to setup International Grid Trusted Federation (IGTF)Grid CA in HKU • (interview next week) • If OK, HKU issued certificates will be accepted by various grid consortiums

37. Looking Forward • Without HPC, no incentive • Without Grid, no prospective Thank you !