Zobrazeno 1 - 10
of 85
pro vyhledávání: '"Wilfried Schoepe"'
Publikováno v:
Journal of Low Temperature Physics. 187:195-220
The flow of superfluid $$^4\hbox {He}$$ around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity $$v_\mathrm{c}$$ that scale
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::1f8aa52f49448956e19e55d01ba033ad
https://doi.org/10.1007/s10909-017-1745-7
https://doi.org/10.1007/s10909-017-1745-7
Autor:
Wilfried Schoepe
Publikováno v:
Journal of Low Temperature Physics. 186:121-126
Vortex shedding from a microsphere oscillating in superfluid $$^4\hbox {He}$$ at mK temperatures is compared with that from a laser beam moving in a Bose–Einstein condensate as observed by other authors. In particular, in either case a linear depen
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::aa437f6d7371b6efa8ef66dbcbc2610d
https://doi.org/10.1007/s10909-016-1653-2
https://doi.org/10.1007/s10909-016-1653-2
Autor:
Wilfried Schoepe
Publikováno v:
Journal of Low Temperature Physics. 173:170-176
The onset of turbulent flow around an oscillating sphere is known to occur at a critical velocity $v_{c} \sim\sqrt{\kappa\,\omega}$ where κ is the circulation quantum and ω is the oscillation frequency. However, in a small interval of driving force
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b5abd2bbde44c1401333bc8fda437a6d
https://doi.org/10.1007/s10909-013-0888-4
https://doi.org/10.1007/s10909-013-0888-4
Autor:
Wilfried Schoepe
Publikováno v:
Journal of Low Temperature Physics. 161:526-535
The flow of superfluid helium at very low temperatures around an oscillating microsphere is known to be unstable slightly above the critical velocity. The flow pattern switches intermittently between potential flow and turbulence. From time series re
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c83ad17c1bb3b150310567cfac0403d3
https://doi.org/10.1007/s10909-010-0208-1
https://doi.org/10.1007/s10909-010-0208-1
Autor:
Risto Hänninen, Wilfried Schoepe
Publikováno v:
Journal of Low Temperature Physics. 153:189-196
The critical velocity vc for the onset of turbulent drag of small spheres oscillating in superfluid 4He is frequency dependent (omega/2pi from 100 Hz to 700 Hz) and is described by vc = 2.6sqrt(kappa*omega), where kappa is the circulation quantum. A
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6aab15688b1e8611cc1328fb667da320
https://doi.org/10.1007/s10909-008-9834-2
https://doi.org/10.1007/s10909-008-9834-2
Autor:
Wilfried Schoepe
Publikováno v:
Journal of Low Temperature Physics. 150:724-729
Oscillating solid bodies have frequently been used for studying the properties of normal and superfluid helium. In particular, the transition from laminar flow to turbulence has attracted much interest recently. The purpose of this note is to review
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a3743d60c542dd90fdffdcd73e71191c
https://doi.org/10.1007/s10909-007-9608-2
https://doi.org/10.1007/s10909-007-9608-2
Autor:
M. Blažková, W. F. Vinen, D. Schmoranzer, Vladimir Eltsov, P. Skyba, Wilfried Schoepe, M. Človečko, E. Gažo, Matti Krusius, R. E. Solntsev, J. J. Hosio, R. de Graaf, Ladislav Skrbek
Publikováno v:
Journal of Low Temperature Physics. 150:525-535
Oscillating objects such as discs, piles of discs, spheres, grids and wires have been widely used in cryogenic fluid dynamics and in quantum fluids research since the discovery of superfluidity. A new addition are quartz tuning forks, commercially av
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::1c1083395aac065c2797d0400335020f
https://doi.org/10.1007/s10909-007-9587-3
https://doi.org/10.1007/s10909-007-9587-3
Autor:
Wilfried Schoepe, M. Niemetz
Publikováno v:
Journal of Low Temperature Physics. 135:447-469
The flow of superfluid helium around a vibrating microsphere is investigated at temperatures between 1 K and 25 mK. At small oscillation amplitudes pure potential flow is observed, the linear drag force on the sphere being determined only by ballisti
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::ff76dfa9c7169b0c673472a9b7faa5e0
https://doi.org/10.1023/b:jolt.0000029507.98543.1d
https://doi.org/10.1023/b:jolt.0000029507.98543.1d
Autor:
Wilfried Schoepe, M. Niemetz
Publikováno v:
Journal of Low Temperature Physics. 126:805-814
We investigate the statistical properties of single phase slip events observed in vortex nucleation experiments in 4He by the groups in Berkeley and Paris. From the cumulative distribution function of the events we calculate the sliprate as a functio
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::daffe85af58ecc1d32fca64e9cc478cb
https://doi.org/10.1023/a:1013830221770
https://doi.org/10.1023/a:1013830221770
Publikováno v:
Journal of Low Temperature Physics. 126:287-296
Superfluid flow around an oscillating microsphere is investigated at temperatures down to 25 mK. Stable laminar flow below a critical velocity and turbulence at large drives are found to be separated below 0.5 K by an intermediate range of driving fo
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::d83a2ef34f724e75066f87040b3a1e2c
https://doi.org/10.1023/a:1013732715660
https://doi.org/10.1023/a:1013732715660