Video Lesson – 07/06/2013 – Hydrodynamic Modelling of Pilot-Wave and boucing droplet coupling in a Faraday Problem

Posted by on Jul 21, 2014 in Blog, On the web, Videos | 0 comments

“Recent experiments by two groups, Yves Couder (Paris) and John 
Bush (MIT) have shown experimentally that droplets will bounce on the 
surface of a vertically vibrated bath (instead of coalescing with it), 
generating a Faraday-type wavefield at every bounce. From this state, a 
pitchfork symmetry breaking bifurcation leads to a “walking” state whereby 
the bouncing droplet is “guided” by the self-generated wavefield – the 
droplet’s pilot wave. Once this state is achieved a large array of 
interesting dynamics ensues with surprising analogies to quantum 
mechanical behaviour. We will present a coupled particle-fluid model that 
can can be used simulate the dynamics of this problem. This is joint work 
with John Bush, Andre Nachbin (IMPA) and Carlos Galeano (IMPA)”

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Influence of a local change of depth on the behavior of bouncing oil drops

Posted by on Jul 20, 2014 in Bibliography, Blog, Core Bibliography, Photos, Videos | 0 comments

Carmigniani, R., Lapointe, S., Symon, S., & McKeon, B. J. (2013). Influence of a local change of depth on the behavior of bouncing oil drops. arXiv preprint arXiv:1310.2662.

http://arxiv.org/pdf/1310.2662.pdf

Full (Subscription required) : http://www.sciencedirect.com/science/article/pii/S0894177713003038

From caltech Mc Keon Research Group : http://www.mckeon.caltech.edu/publications/journal.html

 

Abstract :

The work of Couder et al [1] (see also Bush et al [3, 4]) inspired consideration of the impact of a submerged obstacle, providing a local change of depth, on the behavior of oil drops in the bouncing regime. In the linked videos, we recreate some of their results for a drop bouncing on a uniform depth bath of the same liquid undergoing vertical oscillations just below the conditions for Faraday instability, and show a range of new behaviors associated with change of depth.

This article accompanies a uid dynamics video entered into the Gallery of Fluid Motion of the 66th Annual Meeting of the APS Division of Fluid Dynamics.

caltech setup

 

 

 

And a very interesting video showing the influence of depth on the trajectory :

Source : http://arxiv.org/src/1310.2662v1/anc/V102356_InfluenceLocalChangeDepth_BouncingDrop.mp4

 

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Dotwave @ 240 frame per Seconds with modified GoPro

Posted by on Jul 20, 2014 in Blog, Featured, Original videos, Videos | 1 comment

This is how precise my temporal resolution can be with my modified goPro and (at last) a good lens : 240 fps ( @848×480 )

Forcing freq is 60 Hz, so Faraday Freq is 30Hz, so for the usual walking mode we have 8 frame during the period of the vertical dynamic. Hence we can observe the dynamic without any strobe effect.

Question: What is the (m, n) mode of the first droplet shown in the movie ?

 

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Surfer DotWave attached to a spring moving with no viscosity

Posted by on Jun 25, 2014 in Blog, Featured, Numerical Simulation, Original videos, Videos | 0 comments

Surfer attached to a spring moving with no viscosity

Integration of motion equation is done continuously via matlab DELAY DIFERENTIAL EQUATION (ddesd) solver

Hence, the dot “reads” continuously the value of the field

In the mean time, the dot “writes” to the field evry T_F (that is a “bounce”) : at each bounce, a local wave field represented by a Bessel JO function is created, which is then slowly damped (That is the memory Me parameter)

Interferences between the waves created by the last previous 300 bounces (THAT IS THE CUTOFF parameter) are computed at each integration step to obtain the shape of the wave and the motion of the dot.

 

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Spin Inversions

Posted by on Jun 25, 2014 in Numerical Simulation, Original videos, Videos | 2 comments

On this purely deterministic superfluid simulation of a dotwave in a harmonic potential ( dot attached to a spring, no viscous dissipation, D=0), the dot has successive clockwise and anti-clockwise circle-like motions, separated by intermittences with null mean angular momentum

 

 

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Dotwave in a box : emergence of normal mode

Posted by on Jan 19, 2014 in Blog, Featured, Original videos, Videos | 2 comments

On this video, the walking droplet is confined in a small cavity (Approx. 6 to 8 times the faraday wavelength)

We observe the emergence of several normal modes of vibration of a walking droplet in a circular corral.

At first, the movement seems “random”, then, the whole wave-particle system synchronizes, and starts turning alltogether.

Differrent modes are possible, with different radius for the droplet trajectory : on this video we see a mode with the droplet on a large radius trajectory, and also a mode where the droplet is on a short radius trajectory

Its seems that thoses radius coincide with with the knots ofs thefaraday standing waves of the cavity, hence we have a quantization of the radius of the different trajectories.

 

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