You know I like to point out where you can spot hydrodynamics concepts in your everyday lives (at least if your everyday lives include strolls along rivers and generally a lot of water) A while back we went to Geesthacht. We were hoping for more ice on the Elbe river, but sadly there was none. […]
Looking at a creek on a Sunday stroll, and seeing lots and lots of concepts from hydrodynamics class. For example below, you see waves radiating from each of the ducks. And you see interference of waves from all those ducks. What happens if the ducks bring their waves closer? At some point, all those waves from […]
Hydraulic jumps, especially submerged ones, are a very theoretical concept for many students, one that occurs in a lab experiment if they are lucky, but more likely only seems to exists in videos, drawings, and text books. But we can observe them all the time if we know what we are looking for! They don’t only […]
Last week I went to beautiful Lüneburg with a group of climate scientists to continue working on a very exciting project I’ve been involved in over the last year or so (see “scales in the climate system” funded by CliSAP here). I so enjoyed being with a group of people who talk about converging solutions of […]
Another neat experiment in the collection I’ve recently been talking about is measuring pressure at different points on a wing profile. It’s not terribly surprising that – as long as the wing is oriented in the correct way in the flow – pressure is high below the wing and low above it. Kinda the whole […]
Another one of those awesome hydrodynamics toys: A Pitot tube! This is what it looks like: What you can’t see here is the little hole at the tip of the tube that is pointing downwards in the picture. What the Pitot tube measures is the pressure difference between that hole (the stagnation pressure since it’s […]
On Monday I posted about playing with Venturi tubes. Guess what: We are going to play more today! Because today the Venturi tubes are connected to a “proper” manometer: Now, if I wasn’t so lazy this would be a great opportunity to get good readings of the pressure differences caused by different flow rates. However, […]
A Venturi tube is one of the things one hears about in hydrodynamics class all the time, but one never gets to see them for real. And even though I just said on Friday that the thing that I found most fascinating in the aerodynamics collection I got to borrow recently was to see how […]
One of the things that fascinated me most when playing with the huge fan we used to look at the flow downstream of a paddle was how the flow direction reverses. Unfortunately (alas, it was to be expected) we didn’t really see this on the paper towel stream line test I did the other day. But […]
We’ve been talking about stream lines a lot recently (see for example the flow around a paddle or flow around other stuff). I’ve always heard stories about a neat way of visualizing stream lines that I wanted to show on my blog. So I set out to try it, but it just never worked exactly the […]
We’ve played with the flow around a paddle recently, and you didn’t really believe I stopped there, did you? Of course I didn’t! But I have many many hours of video footage, and I haven’t had the chance to sift through all of them yet. So here’s a preview of what is about to come […]
My sister and I did a little sight-seeing tour in Hamburg the other day, and one of the most fascinating things I saw was — a diving duck. Now, that is not a reflection of how exciting the rest of Hamburg is, but if you don’t see it after watching the movie below, when you read […]
Recently, someone at my university told me about a case of experiments connected to aerodynamics* that they occasionally use for demonstrations and outreach. Obviously, I asked if I might possibly borrow the case, and fast forward: my dad and I spent a whole weekend playing. I’m gonna go through all the experiments over the next […]
A common problem in hydrodynamics is to distinguish between all the different kinds of lines that characterize a flow field: Stream lines, streak lines, path lines, time lines, and probably more that I can’t think of right now. A common way to think of streak lines is that they are similar to hairs caught in the flow of […]
I’ve promised a long time ago to write a post on vorticity (Hallo Geli! :-)). So here it comes! Vorticity is one of the concepts in oceanography that is often taught via its mathematical formulation, and which is therefore pretty difficult to grasp for those of us with less mathematical training. But it’s also a […]
As you might know, I really enjoy reading the water – watching the water trying to figure out what processes caused the patterns I see. So here are two more movies from my recent Birthday trip. First, look at the Este and tell me: Which way does the water go? And then a second look at […]
That was quite a teaser on Wednesday, wasn’t it? I said I had the solution to any hydrodynamics problem you might want to illustrate. So here we go: I recently had the privilege to be given a private demonstration of the “Elbe” flow solver, which is being developed at Hamburg University of Technology. Elbe allows […]
Why downscaling only works down to a certain limit When talking about oceanographic tank experiments that are designed to show features of the real ocean, many people hope for tiny model oceans in a tank, analogous to the landscapes in model train sets. Except even tinier (and cuter), of course, because the ocean is still […]
Density-driven flow. The experiment presented in this post was first proposed by Marsigli in 1681. It illustrates how, despite the absence of a difference in the surface height of two fluids, currents can be driven by the density difference between the fluids. A really nice article by Soffientino and Pilson (2005) on the importance of the Bosporus […]
More movies of my kitchen sink. I am really fascinated by the hydraulic jumps in my kitchen sink. I can’t believe I haven’t used this before when I was teaching! Yes, movies of rivers and rapids are always really impressive, too, but how cool is it to be able to observe hydraulic jumps in your […]
Water changing its velocity from above to below the critical velocity. Recently in beautiful Wetzlar: The river Lahn flows through the city below the medieval cathedral at sunset. And I’m showing you this because we can observe a hydraulic jump! A hydraulic jump occurs when water that was flowing faster than the critical speed suddenly […]
