Is tracking starlings as difficult as tracking particles?
I guess the answer is yes and no. In some aspects their motion is much more “violent”. In other sense, it’s less rapidly changing than the motion of particle in the turbulent flow (especially small particles). Or maybe I’m wrong 
There is very interesting research of the STARFLAG group that one could read about here -> and there
French micro plane fast forwards to hover
the simply looking micro air vehicle with a fixed wing and two COUNTER rotating propellers. that’s all one needs to get hoovering and forwarding flight.
Read more on ….
The pain and turbulence analogy
Watching the kids I notice that it’s very good that they feel pain for their small accidents – this is precisely the preventive mechanism of dangerous things they might decide to do otherwise. Why? Because they have too much energy and they need to dissipate it. While dissipating not fast enough, the energy is converted to kinetic energy and then …..
What I do understand that this is almost the same unifying principle for which turbulence exists – this is the mechanism that prevents the pre-existing potential energy (e.g. water, gravity and elevation that leads to fast river flows and to turbulence) to convert into too high kinetic energy – these are natural “brakes” that prevent our nature from disasters. Imagine Volga River without turbulence – the flow will reach speeds of thousands of kilometers at the lowest portion – it will simply destroy the Earth, by splashing the Caspian Sea.
from the group of fluid education of APS
PS, Here is a fun example of conservation of momentum to show your classes:
http://www.youtube.com/watch?v=I66rsg2DaHw
Convservation of momentum
Looking for postdoc/ph.d.
Postdoctoral and Ph.D. research positions
http://docs.google.com/present/view?id=ah85jtcktks4_1383fvst34gw
one of the lecture series you shouldn’t miss:
Course Description
The goals for the course are to gain a facility with using the Fourier transform, both specific techniques and general principles, and learning to recognize when, why, and how it is used. Together with a great variety, the subject also has a great coherence, and the hope is students come to appreciate both.
Topics include: The Fourier transform as a tool for solving physical problems. Fourier series, the Fourier transform of continuous and discrete signals and its properties. The Dirac delta, distributions, and generalized transforms. Convolutions and correlations and applications; probability distributions, sampling theory, filters, and analysis of linear systems. The discrete Fourier transform and the FFT algorithm. Multidimensional Fourier transform and use in imaging. Further applications to optics, crystallography. Emphasis is on relating the theoretical principles to solving practical engineering and science problems.
The Fourier Transform and its Applications | Stanford Video Course
very happy to solve an annoying thing of our 3D-PTV software
Since I know this software, http://ptvwiki.netcipia.net, I’m very happy with it, besides few annoying things. One of them is that every time you move your source directory, you have find the file “ptv.tcl” and manually edit it. I couldn’t believe it’s not possible in Tcl/Tk to make it programmically. Now, during the last visit I was just so annoyed by this thing (especially because we set up the SVN control and everyone of us changes this file according to his directory) that I looked for it and found the solution:
lappend auto_path [file dirname [info script]]
lappend auto_path “.”
Replace the
set auto_path
line by the two lines above and you’ll never have to touch the ptv.tcl file again.
awesome video of flow visualization of a vortex behind a cylinder
Vortex shedding mechanism from a circular cylinder. Experimental flow visualisation with hydrogen bubbles and a laser sheet in a water channel. By Gustavo Assi, London, March 2008.
Vortex shedding from a circular cylinder
