Thermoviscous Hydrodynamics in Non-Degenerate Dipolar Bose Gases

TL;DR

This paper develops a hydrodynamic model for ultracold dipolar Bose gases, deriving anisotropic viscosity and thermal conductivity tensors to describe their unique transport properties influenced by dipolar interactions.

Contribution

It provides an analytic derivation of anisotropic viscosity tensor coefficients for dipolar Bose gases, extending previous work on thermal conductivity to a comprehensive hydrodynamic framework.

Findings

Anisotropic transport tensors depend on dipole orientation.

Dipolar anisotropy affects wave attenuation in the fluid.

The model captures the influence of dipolar interactions on hydrodynamics.

Abstract

We present a hydrodynamic model of ultracold, but not yet quantum condensed, dipolar Bosonic gases. Such systems present both $s$-wave and dipolar scattering, the latter of which results in anisotropic transport tensors of thermal conductivity and viscosity. This work presents an analytic derivation of the viscosity tensor coefficients, utilizing the methods established in [Wang et al., arXiv:2205.10465], where the thermal conductivities were derived. Taken together, these transport tensors then permit a comprehensive description of hydrodynamics that is now embellished with dipolar anisotropy. An analysis of attenuation in linear waves illustrates the effect of this anisotropy in dipolar fluids, where we find a clear dependence on the dipole orientation relative to the direction of wave propagation.