Nabla
Musicians choose chords for a beautiful melody, we apply low-carbon technologies for a high-performance building.
Start Simple
Wentao Wu
To all the talented scientists I have worked with and especially to my future students.
"If you want to simulate a tree, start with a leaf." - Thijs Defraeye (Senior Scientist at Empa)
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If I have to pick a single most important thing that I learned during my junior research stage, it is definitely the above quote from Dr Defraeye. As a postgraduate student, you must be very excited to start your project. For example, your project is to understand the cooling effect of the fern tree due to evaporation and shading. You would intend to build the entire tree and simulate both evaporation and shading in the first place. 99% of the time, the result is simulation crash over and over again. It will be very difficult for you and your advisor to figure out the reason. It could be due to the geometry of the tree, the mathematical model for solar radiation, or the mathematical model for evaporation.
The solution is 'Start-Simple'. You should start to simulate the evaporation of a leaf or even a small part of a leaf. Once it is successful, you add shading of solar radiation. Then you extend your model to a branch then to a tree. During the workflow, you probably still need a lot of simplification. For example, you might have to use a simple mathematical model to represent the leaf once it is applied to the whole tree.
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I went through this process in a hard way. One topic of my PhD project was to simulate the indoor environment of a cow stable. I built the entire stable with 167 cows. I got stuck for months. My abroad advisor - Prof Jonh Zhai from the University of Colorado Boulder, just said one sentence to solve the problem 'start from an empty stable'. This is exactly the same as Dr Defraeye's 'Tree-Leaf' theory.
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'Tree-Leaf' also becomes the very first conversion between me and my postgraduate students.
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Christchurch, New Zealand
Noon 09 June 2023
