One in a series of posts about an aeronautical engineering course I created this year.
The aim of this fifth project was to work with the main fluid mechanics notions and phenomena at play in a small, subsonic wind tunnel. The accompanying lecture was a review of the important notions (theoretical flow, the effects of friction, and scaling techniques) needed to work on the project.
This was by far the richest and most ambitious lecture of the course. I set out to sweep across a very large amount of material in a lecture that was structured as though it was a review of the entire fluid mechanics discipline. In retrospect it is easy to see that this was rather foolish, perhaps in part because the coverage can be neither thorough nor complete (and indeed important parts such as computer fluid dynamics or compressible flow are not even mentioned), but especially because the lecture then lacked focus.
The students were not helped by this lack of clear purpose. I too had difficulties, as I was taken aback by how little connection I could make with the student’s existing knowledge. Finally, because of the sheer volume of material, the English language was a particularly heavy overdraft that day.
Nevertheless, I believe the lecture was a decent attempt at putting together the puzzle pieces acquired over the semesters. Indeed, I am convinced that the largest shortcoming of our fluid mechanics and derivative courses are that they fail to explain where and how the different types of analysis fit together in the big picture. For example, compressibility effects and boundary layer theory are always taught entirely separately, so one may never find out in university that they in fact may both together be useful for the study of a particular flow. I hoped to present familiar concepts under the light of their usefulness (or not) in studying simple real-world applications.
The project focused on applied aerodynamics, and required mixing elements of design, scaling techniques, theoretical fluid mechanics, and approximation techniques. I hoped to give students a taste of the aerodynamicist’s job by coming to grips with the shocking amount of restrictions inherent to wind tunnel testing, as well as the overwhelming presence of empirical, experience-based rather than theoretical work.
The project purposely left a lot for the students to decide by themselves, and I never thought they would hate this as much as they did! I could not convince anyone that there is no optimal wind tunnel design at all, lest even that the objective was to get a grasp of the main notions at play, not produce cutting-edge data. Clearly the threshold that must be overcome to reach the most interesting parts of the project was too high.
I think the main missing ingredient in this session was fun. The path through the lecture and project is full of discomfort, as none of the beautiful theories, neat-and-unique results, and usual certainties hold — real aerodynamics is hard!
In the next edition I will cut down as much as I can on the lecture and project contents so that the key aspects of the project can be handled earlier on. I will work on getting more of my enthusiasm for the topic through. Students reported that they liked this project least of all although they felt it was interesting and important. That’s a good starting point for improving.