Our most famous fluids tend to be transparent — air and water, for example. This makes it hard for us to imagine how fluids are moving as members of the general public, but also poses an interesting problem for budding engineers. They need to know how to make fluids do what they want them to do. So, Jean Herzberg in the Mechanical Engineering teaches a flow visualization course here at CU. She does it in a fairly novel way, as a hands-on art and science course.
There’s a lot here. Some of the things she covers are photographic techniques, flow visualization techniques, some of the physics and phenomenology of fluids such as fluid rotation. She spends a lot of time on cloud physics. “I’ll never be able to ignore the sky again,” says one participant. But interestingly she also spends some time on the history of photography, which has evolved from a science to an art.
This is the only course in existence on flow visualization! (and it shows up first in Google searches for “flow visualization”.) She gets some envy from colleagues when she presents her results at conferences, whose courses tend to be highly mathematical. It’s unusual to mix art and science in quite this way, in which art students are expected to document and experiment, whereas the engineering students are expected to create expressive images with impact. The idea that engineers could learn something by creating something themselves is unheard of, and this enrages her. And in the end, the engineers create images that are just as compelling and indistinguishable from those of the artists.
In the experiments that students develop at home, they use everyday household fluids, which are environmentally benign. Usually toxic materials are used in laboratory courses, which is really unnecessary. She finds that she can’t explain the unusual physics of some of their observations. It’s also challenging because the exact properties of many of the materials used, such as food coloring and WD40. Combustion and fluorescence, she says, are always popular (natch). For example, one group wanted to make green flame, so poured flaming methanol in boric acid. Another made a negative image of smoke changing from laminar to turbulent flow as it exited the mouth. The images she showed us were from her 2009 class which will be on the web shortly, but in the meantime you can see many amazing student images in their galleries. The artistry of these images is astounding — the play of light and color, the use of humans as backdrops but using fluid flow as the main focus of the image. The science of the images is also compelling. One group of students discharged a fire extinguisher underwater, and saw three phases of matter (solid, liquid, gas) within that image. A Tesla coil arcing through the air shows interesting patterns, showing discontinuities in the breakdown of air.
Students also take many images of clouds as part of their assignments, which are also on the gallery page. Anyone who lives in Boulder knows that it’s an amazing spot for clouds — with the Rockies nearby and some interesting atmospheric conditions we get some curious clouds that I’ve never seen anywhere before.
What is the impact of this course on her students? She finds, anecdotally, that students experience life-altering changes after the course, and her surveys show that students’ beliefs and attitudes change to be more enthusiastic about fluid flow and they notice fluid flow in everyday life. (Why doesn’t she see this kind of change in her traditional engineering courses?) She sees changes in students perceptions of the discipline and the physics. Students feel better about the material — they see fluids as beautiful, interesting, useful, and fun. Traditional fluid mechanics course students have negative responses on most of these — they see fluids as not beautiful, useful, and it’s not something they feel able to do. This reminds me of my time at the Exploratorium, where I was first exposed to the incredible aesthetics of science, and the intersection between art and science. I began to notice all sorts of little, beautiful things — the cracks in the sidewalk, light on a puddle, swirls of milk in my coffee. I still do. Life-altering experiences? You betcha.
This is another kind of way of knowing fluid mechanics. These students could probably point to the sky and explain things about fluid mechanics that those who learned to do the calculations can’t. Note, however, that the engineering students in this flow visualization course have already taken the calculational fluid mechanics course. I wonder, how would students in the traditional fluid mechanics course see that course differently if they took this visualization course first?