1. OVERVIEW OF INTENSIVE COURSE
The intensive course (IC) entitled “A journey around the edge of wind engineering” delivered by Prof. Chris Baker from the University of Birmingham aimed to show a range of research that is somewhat different to “normal” wind engineering studies of wind loads on structures, as well as to show how wind engineering tools can be used in a variety of different situations. There were 5 lectures; the first was on the wind environment, and the rest were about wind effects on people, transport networks, on the built environment, and on agriculture. The first two lectures were given on January 18, 2011, the next two were given on January 19, 2011, and the last one was finished on January 20, 2011. Each lecture was about an hour and a half long, and started at 14:00 on each lecture day.
2. SUMMARY OF LECTURES
The first lecture about the wind environment essentially described the nature of different kinds of wind from different wind storms that we consider in wind engineering. Work on laboratory-scale simulation of thunderstorms was also discussed, highlighting the difficulty in selecting the appropriate mechanism to do so. Gust fronts were also shown to have a different velocity profile from mean winds. Finally, research work primarily in the UK on climate change and resilience were presented.
In the second lecture, wind effects on people, particularly pedestrians, were discussed. Pedestrian comfort criteria from different standards were compared and assessed, and then recent work at the University of Birmingham were discussed, which included conduct and analysis of perception surveys, and laboratory and mathematical modeling of pedestrian stability.
In the third lecture, wind effects on transport systems, primarily on road and rail networks and in part on power networks, were tackled. Damages to these transport systems were first discussed for the students to gain appreciation on the subject. Wind conditions relative to vehicles, full-scale, laboratory-scale, and computational (i.e. CFD) methodologies, and risk analysis and alleviation methods were the main topics.
In the fourth lecture, wind effects on the built environment, particularly building ventilation, atmospheric pollution, and wind energy were discussed. The “stack effect” concept was discussed and emphasized in a number of applications. Sources of air pollution were also presented as a background to the topic of air pollution, as well as accounting for wind speed and wind direction probabilities. Wind characteristics in urban areas that could help disperse or exacerbate are also briefly discussed. Full-scale, wind tunnel, and CFD methods were again discussed. Finally, examples touting the idea of harnessing wind energy from around building envelopes were presented.
In the fifth and last lecture, “wind effects on agriculture” was the final topic. The discussion was particularly on wind effects on crop and on trees. Mathematical modeling and full-/field-scale wind tunnel testing of wind effects on crop was carried out and arrived at significant conclusions.
3. DISCUSSION POINTS
3.1. Overall objective
Overall, this intensive course was somewhat a summary presentation on the state-of-the-art in “non-conventional” wind engineering, wherein the mathematical details behind the different research work shown was left to interested audience members to delve into. In this sense, the course’s second objective was certainly met. There were not much citations of specific literature though, but the professor mentioned that we could reach him to ask about where we can find the reference materials relevant to the topics.
This report author does not have years of experience in wind engineering, not like the professor has, but the former would not consider environmental wind engineering to be “non-conventional” wind engineering as the professor has somehow implied by presentation of the topics of lectures 2 and 4 (and that structural wind engineering is “normal” wind engineering). Nonetheless, the concept of “pedestrian stability” was still certainly something new in the field of pedestrian wind environment studies. And it must be a fact that there are more wind engineers practicing civil/structural/architectural wind engineering than environmental wind engineering. And so from the perspective of such a majority of wind engineers, these are certainly “non-conventional.” An example is the New Frontier of Education and Research in Wind Engineering, the Global Center of Excellence (GCOE) Program at Tokyo Polytechnic University (TPU), which has divided wind engineering into 3 areas: area of strong (structural engineering), moderate (building ventilation), and low winds (pedestrian comfort, air pollution). However, the proportion of professors alone for each area (6:2:1) but also of students and researchers somehow suggests that indeed, the structural aspect is somewhat the “normal” wind engineering. This was a very welcome lecture to us mostly “normal” wind engineers.
3.2. Lecture 1: wind environment
Although this author understands the use of the term “wind environment” for this lecture title, it is somewhat tricky because the word “environment” itself has another meaning in wind engineering, such as that described in the previous subsection. Some similar terms that could reduce some initial confusion for lecture attendees are “wind (field) characterization,” or “nature of wind (storm systems),” as certainly the types of wind systems are the first discussion topic within this lecture. Perhaps “environment” was selected for parallelism with the titles of succeeding lectures where “effects,” also starting with the letter “e,” succeeded the first word, “wind.”
The professor described some differences in the characteristics of 4 different wind systems, i.e. extra tropical cyclones, tropical cyclones, thunderstorms, and tornados, by way of showing anemograph traces, except for tornados, which is understandably but unfortunately quite difficult.
The next topic was on the nature of gust fronts, which is generally not a new topic (e.g. see Kwon and Kareem, 2009), but this lecture has shown what appears to be new finding that is generally contrary to previous belief about the nature of such gust fronts.
New work that the professor’s group has carried out is laboratory-scale simulation of thunderstorm winds. The concept used itself is similar to the laboratory-scale tornado simulation being carried out also at the GCOE Program in TPU, although of course tornados and thunderstorms are two different wind systems. Difficulties in achieving closer-to-reality thunderstorm simulations from three different methodologies were also discussed; i.e. fan direct control, aperture opening, and vertical flaps. The professor did not discuss if the combination of two different methodologies (i.e. vertical flaps AND fan direct control) were tried, or how this or other combinations may have been ruled out.
Lastly on climate change and resilience, the professor pointed out the initial difficulty of communicating with other experts (e.g. meteorologists) due to a gap in terminology. For example, for engineers a 100 km area is already large-scale, but for meteorologists a 1 km area is still micro-scale. The professor also said that “meteorologists do not do wind very well at all.” This is an observation made by this report author as well. (e.g. see Aquino, 2005)
3.3. Lecture 2: wind effects on people
A new topic discussed in this lecture that is of significant interest to this author is pedestrian stability modeling. A similar model could be used for understanding occupant comfort in tall and slender buildings under high winds.
A second interesting point made by the author is that computational fluid dynamics (CFD) is becoming more and more the tool of choice. The professor always mentions this and two other, more traditional but equally important tools for wind engineers: full-scale measurements, wind tunnel tests, and CFD. Per the author’s recollection, it was in this lecture that the professor mentioned that the late father of wind engineering, Prof. Alan G. Davenport, said at one of the recent International Conferences on Wind Engineering something to the effect of “You are not a wind engineer until you do full-scale measurements.” That is a very significant piece of advice for all of us studying to become or currently practicing wind engineers.
One more very interesting fact shown by the professor through his presentation on different pedestrian comfort criteria is how it is geographically-dependent; i.e. comfort criteria are different for people from different countries with very different climates such as Germany, France, the UK, and Canada. This author has himself thought of including a "design-dependent factor" in parameter estimates for wind-resistant design; i.e. see Aquino, 2006.
3.4. Lecture 3: wind effects on transport networks
The professor considered wind effects on rail and road networks as “non-conventional” wind en-gineering, but from the limited knowledge of this author it does not seem so. It could be that wind effects on trains and vehicles for example would typically be the concern of pure aerodynamicists, not civil engineers in the field of transport planning.
The professor again talked about the three most important tools for wind engineers today: full-scale testing, laboratory-scale wind tunnel testing, and CFD. While it appears that CFD is the most cost-effective and in some cases possibly the most accurate, it is actually very expensive to carry out as, for example it required more processing power to analyze wind around vehicles than astrophysics applications.
An interesting component of the work by the professor related to wind effects on vehicles is the use of natural wind for experimental wind engineering at the full-scale test site with typical rural terrain at the Silsoe Research Institute, in collaboration with the University of Birmingham.
Lastly, it was emphasized later in this lecture (and this is perhaps what this author considers non-conventional wind engineering) that the governing wind speed criteria for use of most bridges (i.e. gusts ranging from around 15 to 30 m/s) is lower than those in “normal” (i.e. structural) wind engineering (i.e. gusts ranging from 30 m/s and higher). This is somewhat a research focus as well of this author whose current study is, although still under the “normal,” structural aspect, looking at wind effects on structures at such a relatively lower amplitude range.
3.5. Lecture 4: wind effects in the built environment
Initially, the title of this lecture sounded like “wind effects on the built environment,” and thus seemed like a conventional topic in wind engineering. But it is in fact all about addressing air pollution and building ventilation, which are the two other aspects of wind engineering as defined under the GCOE program at TPU.
In this field, CFD was said to be a preferred choice, as wind tunnel tests are yet to be capable of simulating the thermal conditions as well of the atmosphere. The professor recognized that TPU had one of very few wind tunnel laboratories that could do such.
Lastly, a “new” concept not normally discussed in wind engineering lectures although possibly an “old” concept that has been already used before is wind-assisted ventilation. Usually, discussions would focus on natural ventilation (i.e. using natural wind to ventilate), mechanical ventilation (i.e. using fans to ventilate, or to create air movement inside buildings), and wind energy (i.e. using natural wind to produce electricity). In some cases these do not or cannot work, but what if these three concepts were combined into one? Wind-assisted ventilation uses natural wind to produce electricity that would power fans that create air movement inside buildings. Essentially, it is still the natural wind (although this time, indirectly) that is used for ventilation.
3.6. Lecture 5: wind effects on agriculture
If any of the main topics were “non-conventional,” the report author would consider the topics of lecture 5 alone as purely non-conventional, as the professor had pointed out, certainly because those in the agriculture sector would not normally consider wind engineering expertise to improve, say, crop production. Likewise, to the best of this author’s knowledge, no one has really tackled the idea of addressing tree and crop failures under high winds.
This was possibly the area most interesting to this author because of experience in identification of post-typhoon damages in the Philippines, which is perhaps the most typhoon-prone country in the world with an annual average of 9 landfalling tropical cyclones. In damages identified after passages of typhoons, it is usually the trees that are primarily affected, but such damages do not directly affect society, but because precisely such fallen trees block roads and damage power lines do they indirectly affect society. In such instances, there is perhaps an attitude of “we can’t do anything about it,” much as for wind-damaged crop fields that indirectly affect food and other essential supply chains. (See Pacheco et al, 2005, 2006, 2007, and 2009.)
But as shown in lecture 5 by the professor, such is not the case. There are a number of things that can be done to reduce or possibly even prevent such damages so that indirect wind effects on society could be correspondingly minimized, if not totally avoided.
4. REPORT CONCLUSION
The author attended the 5 lectures within the Intensive Course given by Prof. Chris Baker entitled “A journey around the edge of wind engineering,” and has prepared this report. The course has been summarized and important and interesting points have been discussed. Overall, although the author would have wanted more mathematics and details and yet it is recognized that the time did not allow it, the author was very pleased and very privileged to have attended the said Intensive Course.
5. RELEVANT REFERENCE
- Aquino, R.E.R., 2005, Philippine wind information for engineering, research, and mitigation, A report prepared for the 21st Century Center of Excellence (COE) Program on Wind Effects on Buildings and Urban environment at Tokyo Polytechnic University.
- Aquino, R.E.R., 2006, "Consideration of dynamic wind effects using a modified Davenport gust response factor formulation in the structural design and evaluation of self-supporting antenna towers in the Philippines," MSc Thesis, University of the Philippines, Diliman, Quezon City.
- Kwon, D, and Kareem, A., 2009, Gust-front factor: new framework for wind load effects on structures. J. Struct. Engrg. 135, 6, 717-732.
- Pacheco, B.M., Aquino, R.E.R., and Tanzo, W.T., 2005, “Wind loading code provisions in the Philippines and iden-tified future improvements,” in: Proceedings of the 2nd Workshop on Regional Harmonization of Wind Loading and Wind Environmental Specifications in Asia-Pacific Economies, Hong Kong, China.
- Pacheco, B.M., Aquino, R.E.R., Tanzo, W.T., and Rosaria, N.E., 2006, “Wind loads and the wind environment in the Philippines: recent developments in 2006,” in: Proceedings of the 3rd Workshop on Regional Harmonization of Wind Loading and Wind Environmental Specifications in Asia-Pacific Economies, New Delhi, India.
- Pacheco, B.M., Aquino, R.E.R., and Tanzo, W.T., 2007, “Wind loading and wind environment in the Philippines: recent developments in 2006-2007,” in: Proceedings of the 4th Workshop on Regional Harmonization of Wind Loading and Wind Environmental Specifications in Asia-Pacific Economies, Shanghai, China.
- Pacheco, B.M., Tanzo, W.T., and Aquino, R.E.R., 2009, “Recent wind engineering developments in the Philippines: 2007-2009,” in: Proceedings of the 5th Workshop on Regional Harmonization of Wind Loading and Wind Envi-ronmental Specifications in Asia-Pacific Economies, Taipei, Taiwan.
- Pacheco, B.M., Aquino, R.E.R., Tanzo, W.T., and Tanchuling, M.A.N., 2010, “APEC-WW-2010 country report: Philippines,” in: Proceedings of the 6th Workshop on Regional Harmonization of Wind Loading and Wind Envi-ronmental Specifications in Asia-Pacific Economies, Gangneung, South Korea.
No comments:
Post a Comment