This week we have two talks in the webinar series from early career researchers.

Speaker 1: Sosuke Inui, Osaka City University (10am UK)

Title: Coupled dynamics of quantized vortices and normal fluid based on the lattice Boltzmann method

We investigate the coupled dynamics of quantized vortices and normal-fluid in superfluid 4He at finite　temperature using a numerical scheme based on vortex filament model (VFM) and lattice Boltzmann method (LBM). LBM is a widely used computational technique that allows us to simulate the Navier-Stokes equation for low Mach numbers, where a fluid flow is treated as a convection of mesoscopic particles from one site to the neighboring sites on the lattice. Although the two-fluid nature of He II makes its flow complex, the particle-like treatment of normal-fluid in LBM reduces the complexity significantly. We show, by comparing our results with those obtained with direct NS simulations by other groups, our numerical scheme reproduces characteristic flow structures that have been reported in preceding numerical studies. We also discuss that there are several unsolved problems that can be potentially dealt with our numerical approach, which was not possible with direct NS-type simulations, such as a vortex-dynamics near a local heat spot.

Speaker 2: Matthew Wheeler, University of East Anglia (10:30am UK)

Title: Relaxation dynamics of half-quantum vortices in a two-component BEC

We study numerically the relaxation dynamics of quantum turbulence in a two-component Bose-Einstein condensate containing half-quantum vortices. We find a temporal scaling regime for the number of vortices and the correlation lengths that at early times is strongly dependent on the relative strength of the inter-species interaction. At later times we find that the scaling becomes universal, independent of the inter-species interaction, and approaches that numerically observed in a scalar Bose-Einstein condensate.