QFS 2016 Book of Abstracts

Abstracts

O3.4 Ultraquantum decay of strongly nonequilibrated BEC turbulence G.W. Stagg, N.G. Parker, and C.F. Barenghi School of Mathematics and Statistics and Joint Quantum Centre Durham-Newcastle, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom Following Berloff and Svistunov (2002) we study the emergence of a macroscopically coherent condensate from the cooling of a thermal gas of weakly-interacting bosons. Starting from a uniformy occupied highly nonequilibrated condition, we track the growth of the low k modes which feature a tangle of quantised vortex lines. Analysis of vortex line density, incompressible energy spectrum and correlation function suggests that the tangle is a random flow without large scale structures similar to the ultraquantum turbulence of Walmsley and Golov (2008) and the counterflow turbulence first observed by Vinen. O3.5 Inhomogeneous quantum turbulence in a channel Makoto Tsubota, Satoshi Yui, Shinichi Ikawa Department of Physics, Osaka City University, Osaka 558-8585, Japan We discuss the numerical simulation of inhomogeneous quantum turbulence in a square channel. The recent visualization experiments revealed inhomogeneous flow profile in a channel. We discuss three topics. One is inhomogeneous structure and dynamics of vortices in thermal counterflow[1]. The second is superfluid boundary layer in pure normal flow, where we found the logarithmic velocity profile of superfluid velocity [2]. The last is coflow turbulence. The simulation finds a novel behavior that vortices are dragged into an attractor by the mutual friction [3]. [1] S. Yui, M. Tsubota, Phys. Rev. B91, 174504(2015). [2] S. Yui, K. Fujimoto, M. Tsubota, Phys. Rev. B92, 224513(2015). [3] S. Ikawa, M. Tsubota, Phys. Rev. B93, 184508 (2016).

76