269 research outputs found
Long range mediated interactions in a mixed dimensional system
We present a mixed-dimensional atomic gas system to unambiguously detect and
systematically probe mediated interactions. In our scheme, fermionic atoms are
confined in two parallel planes and interact via exchange of elementary
excitations in a three-dimensional background gas. This interaction gives rise
to a frequency shift of the out-of-phase dipole oscillations of the two clouds,
which we calculate using a strong coupling theory taking the two-body
mixed-dimensional scattering into account exactly. The shift is shown to be
easily measurable for strong interactions and can be used as a probe for
mediated interactions.Comment: 7 pages, 5 figure
Generalstabens Opmaaling paa Island.
Generalstabens Opmaaling paa Island
De gamle Nordbokolonier i GrĂžnland.
De gamle Nordbokolonier i GrĂžnland
Gennem afsides Egne paa Island.
Gennem afsides Egne paa Island
On bubble clustering and energy spectra in pseudo-turbulence
3D-Particle Tracking (3D-PTV) and Phase Sensitive Constant Temperature
Anemometry in pseudo-turbulence--i.e., flow solely driven by rising bubbles--
were performed to investigate bubble clustering and to obtain the mean bubble
rise velocity, distributions of bubble velocities, and energy spectra at dilute
gas concentrations (%). To characterize the clustering the pair
correlation function was calculated. The deformable bubbles with
equivalent bubble diameter mm were found to cluster within a radial
distance of a few bubble radii with a preferred vertical orientation. This
vertical alignment was present at both small and large scales. For small
distances also some horizontal clustering was found. The large number of
data-points and the non intrusiveness of PTV allowed to obtain well-converged
Probability Density Functions (PDFs) of the bubble velocity. The PDFs had a
non-Gaussian form for all velocity components and intermittency effects could
be observed. The energy spectrum of the liquid velocity fluctuations decayed
with a power law of -3.2, different from the found for
homogeneous isotropic turbulence, but close to the prediction -3 by
\cite{lance} for pseudo-turbulence
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