Category Archives: wave watching

DIY #WaveWatching “fortune teller” on #WaveWatchingWednesday

(Download in English || Download in Spanish; thanks to Felipe Veloso for translating!)

How about a little wave watching game to celebrate #WaveWatchingWednesday?

The minute I saw Andrea Lopez Lang’s tweet, where she made a “fortune teller” (no idea that’s what they were called) as going-away and please-remember-what-you-learned gift for her class, I HAD to make something like that!

Unfortunately I’m not teaching a class right now where I could easily see how this could be done, but luckily there is always wave watching!

Grafic with instructions to build a wave-watching-themed "fortune teller"

Click to get the pdf!

And Kjersti had a great idea for how this could be used right away: To send students out with these toys and ask them to discover one example for each of the waves shown on the toy. Plus then of course document it, and share on social media… ;-)

Waves are traditionally taught in a theoretical and very dry manner, and the transfer to the real world is hardly happening at all (especially since the large tank in the basement at GFI has been demolished, which still breaks my heart), so this is a fun way to get students outside and try & find contents from their lecture in real life.

P.S.: It’s not as difficult as it might seem at first once you start observing and get a little creative. Nobody said that the rock that makes the ring waves had to have been there when you got there, and wakes can be created by ships or bird or even if you pull a stick through the water…

[annotated photo] Photo of water flowing over a weir, annotated with arrows showing particle velocities

Testing the new particle tracking app “Flow on the Go”

The new particle tracking app “Flow on the Go” became available for testing on iOS yesterday. And it is SO AWESOME!!!

The idea is that particle that are advected in a flow can be used to visualize a flow field (similar to what we did when we were at the 13-m-diameter rotating swimming pool in Grenoble, where we added particles with neutral density to the tank in order to track currents). So the app latches on to something that it recognized as “particle” and then displays arrows as it follows that feature from frame to frame. Pretty amazing, isn’t it?

(If you are impatient, scroll to the second-to-last video of this post for my best example, otherwise stay with me as I walk you through different scenarios…)

First, I tested with movies I already had on my phone, for example storm waves in Kiel. Which might not be the nicest test case as wave crests break and thus new “particles” appear, but then vanish in a trough behind another wave etc.. So even though the app tracks them, it all seems a bit messy. The movies always start with a short glimpse of the original movie and then the tracking begins…

 

Then, I tried the “soap protects you from Corona” demo that my adorable nieces are presenting for you. There is water on the plate sprinkled with pepper (or something), and they dip their fingers in with a little bit of dish soap, break the surface tension, and the particles all get pushed to the edge of the plate. (Spoiler alert: Kids’ hands — no matter how cute — will be recognized as particles…. :-D)

 

At this point I decided that it was definitely time for my parents and me to go for a walk to film some flows.

Below: Laminar flow towards the edge, then turbulent flow at the bottom. Interesting observations here (beside the super cool flow field that is captured surprisingly well): Where there is a lot of foam and everything appears white, it’s not easy for the app to find “particles” to trace. And when reflections on the water move (like the handrail when there are waves) that looks like “particles” to the app.

 

Here is one example where there are plenty of bubbles passing by on the other side of the river (which are tracked very nicely) and my dad threw in some leaves on our side so there were particles that showed the recirculation. Nice! (No idea what the app sees in the top left corner, though)

 

Then I had the brilliant idea to film the large scale flow field with lots of bubbles in it. But, as you, dear reader, will probably have guessed already, the reflected trees are the much more dominant signal. That’s what happens when you film tons of things and only process them afterwards…

 

But here is a very nice example for you: Fast, laminar flow upstream of the weir, then a waterfall, a submerged hydraulic jump and turbulence at the bottom. Nice!

 

Back home, I decided I wanted to test some tank experiments. Below I’m first showing a couple of seconds of the original “thermal overturning circulation” movie (because I knew my hands would mess up the particle tracking when I’m dripping dye into the tank) and then cut to the processed one.

I thought that this was one of my better movies with few reflections on the tank, a nice background, etc.. Turns out: Still waaaay too much going on! Reflections on the glass, shadows on the wall behind it as we are watching… I’m sure there are settings in the app that would lead to much better results (if I knew how to use it) but for now I know that using the app is a little more difficult than I thought.

 

In any case, I think it’s a brilliant app, and I am looking forward to playing with it some more and figuring out how to use it best! There are so many settings that I haven’t figured out yet, so I know what I’ll be doing over the next couple of days… ;-) And I can’t wait to use it on our DIYnamics rotating tank experiments!

#WaveWatchingWednesday

Even though I haven’t done a #WaveWatchingWednesday in a looong time, there has of course been a lot of wave watching going on. But the longer I wait with copying all the Instagram posts into a blog post, the more work it gets, the longer I put it off. Vicious circle! But here we go today. Plenty of interesting and plenty of beautiful pics! Enjoy!

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#BergenWaveWatching: Field work right outside our students’ homes

This is a (admittedly terribly crowded — but I only had 1 A4 page and there are so many interesting #BergenWaveWatching stories to tell!) poster that I am presenting on behalf of myself, Kjersti Daae and Elin Darelius at the #FieldWorkFix conference next Tuesday (September 8, 2020). If you would rather listen to my poster’s voiceover than read the transcript below, please feel free to do that here!

Welcome to our poster!

The most important learning outcomes that, in my opinion, need to be achieved with a #FieldWorkFix are to enhance motivation and interest in concepts that are being dealt with theoretically in class, and in the students’ subject in general. When students are isolated in their homes and don’t have an inspiring community of learners in their field around them, it is so important to maintain a connection to their field of study! And one way to do that is by helping them realize that what they study is relevant and meaningful in the way that it helps them explain the world they see (even if they previously neither noticed nor felt the need to explain the waves on a puddle they accidentally stepped in).

There are different types of tasks that can help students achieve that level of observation and fascination with their subject (and if you are interested in what specific tasks can look like, check out the link on our poster, that will lead you to a blog post that links to all the different examples I am giving in the following, with tons of pictures).

For example, students could be asked to find realizations of a phenomenon in the world around them. It’s good to start with an easy example that they can definitely find in many different locations. In our case, “find a hydraulic jump” works well, because those can be generated artificially by turning on the tap in your sink, or can be observed near any weir, most rain gutters, and many rivers. These examples can be shared via the classes content management system or via social media – both work well and offer the added benefit of requiring some sort of description and explanation of what was observed and where, thereby practicing both note-taking and reporting skills.

Students could also be asked to observe a specific phenomenon in a specific place and discuss how the time of observation might have influenced what they saw, and how they would set up a schedule for observations that would be best suited to document the phenomenon. An example for that is looking at a tidal current underneath a specific bridge. Depending on what time and what day it is observed during the spring and neap cycle, the flow might be observed having different strengths or even going in different directions.

I am also a big fan of the more open “find something interesting to observe that is somehow related to the concepts discussed in class”, and being open to what students come up with. If you are worried about students not finding something interesting, I would encourage you to look at my Instagram @fascinocean_kiel, where I have almost 900 pictures of mainly waves (and a few other interesting oceanic phenomena) with explanations of what I saw. Once you start looking, there is physics everywhere!

The best thing about a collection like the one on my Instagram (or the one you are building by asking students to document their observations) is that they can be used for an indoor version of this #FieldWorkFix: Assigning pictures to students with the task to annotate and explain what they see. (Which is surprisingly difficult! I get often sent #FriendlyWaves; pictures of water with the request to explain what is going on there, and while it is very entertaining and educational, it is also really difficult because many of the relevant metadata does not come with a picture).

And finally, one could give the very open task to either come up with, or answer a given, research question by doing observations in the neighbourhood.

Depending on the social distancing requirements, all these tasks could be assigned to students working either in teams or by themselves. But if one of the learning outcomes is to practice working in teams, as it often is, this can be accommodated either way:

Several students can work together on the same research question and either do this together, or – which is most likely the mode they would choose in any case – divide work and take turns taking observations. This means they are also developing observational and collaboration skills: all have to be on the same page when it comes to what properties to observe by which methods and at what place and time, how to document, how much and what kind of metadata needs to be archived, how work is split between the students, et cetera.

Students could also be given complementing tasks that they each complete individually, knowing that they will ultimately have to put their results together like a puzzle. This, again, practices a lot of observational and communication skills.

The results of these tasks can be brought together either asynchronous, i.e. students report back in writing via the content management system or social media, or synchronous in video calls where students give presentations and there is a group discussion.

Lastly, one of the big learning outcomes often associated with field work is building students’ “identity as scientists”. Students come back from the field and talk about how we, meaning we oceanographers, or more generally, we scientists, do field work. Of course, the experience of a local field trip is not the same as a multi-day research cruise. But looking for phenomena related to ones field of study has an effect on how one sees the world. Very quickly, students will look at the world with different eyes, seeing physics where other people see the sparkly ocean or a fluffy cloud. This change in perception helps students feel like a specialist on their subject, as someone who has a deeper interest and wider knowledge than most people around them, and who looks at phenomena more carefully, trying to understand them. And this is a vicious circle: once hooked, it is difficult to stop looking at the world through that lens. Which is exactly what we wanted!

Thank you for your attention!