WFA – Trailing vortices of a passenger jet

The Weekly Fluid Art this week features a plane with its trailing vortices visualized. I would also recommend to read the article on Dauntless Jaunter where the photo was found, it clears some common misconceptions about airplanes and flying.

Fluid mechanics and the human lung

Well, biology and fluid mechanics are tightly bond together. It’s enough if you think about blood flow in your body, blood as a non-Newtonian liquid, the properties of liquids in your ligaments, and of course the flow of air through your lungs.

The following video shows how air flows in your lung during two full breathing cycles. Actually, this animation is really close to my heart, as I wrote my bachelor’s thesis about the flowing phenomena in a particular region of the human lung: those small air bubbles, where exchange of oxygen takes place between the environment and the blood. These small air sacks are called alveoli.

Why is it important to make such simulations? In fact, these investigations are of very big importance. Due to ethical and size constraints it is impossible to make real life experiments like this on humans. In comparison, CFD is cheap and both conditions and geometry can be altered arbitrarily. The results of this research field are directly used in the pharmaceutical industry (e.g. to make better aerosol medicines).

Fluid mechanics is there in your everyday life!

The new S-Class in wind tunnel

You might have already noticed that I am kind of into wind tunnel videos of ground vehicles. The reason might be that I took a class last year at university called “Aerodynamics of Ground Vehicles” which in my opinion was one of the best courses I’ve ever had. I’ve learned a lot from that course, and would warmly recommend to everyone who is interested in fluid mechanics to read some literature on this matter, there are a lot of good books out there.

Today’s video features the brand new Mercedes S-Class tested in a wind tunnel. With Maybach ceasing to exist, the S-Class has to be the top car of Daimler. The goal is nothing else than making the “best car of the world.”

Well, in terms of aerodynamics, they have done a lot to reach that. With a drag coefficient of 0.24 they are very close to values of sports cars! The legendary Opel Calibra had a coefficient of 0.26, so all I can say to Mercedes is well done for creating a limousine that performs better than a sports car! (Even though the Calibra turns 25 next year) This small coefficient will cut the fuel consumption to an astonsihing 4.4l/100km (43mpg) for the S300 BlueTEC hybrid version of the car! (However, I highly doubt that this 4.4 litres can be reproduced in the everyday life. EU fuel consumption norms are veeery inaccurate I think.)

So how does the wind tunnel test look? Continue reading

Aerodynamics of Scania trucks

This week Scania has released a video about current improvements in the field of the aerodynamics of their trucks. What is really important and interesting in the video is that the goal of aerodynamic improvements is not only the reduction in fuel consumption. As you can see in the video, a well-guided flow around the truck body is also important for minimizing the amount of dirt that gets on the door handle. Another important aspect of the aerodynamics is to minimize the flow generated noise. It’s beneficial both for the driver and the environment.