Thermoviscous hydrodynamics in nondegenerate dipolar Bose gases

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 paper presents an analytic derivation of the viscosity tensor coefficients, utilizing the methods established by Wang and Bohn [R. R. W. Wang and J. L. Bohn, Phys. Rev. A 106, 023319 (2022)], 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.

Automated summary

We present a hydrodynamic model of ultracold, but not yet quantum condensed, dipolar bosonic gases. The viscosity tensor coefficients are analytically derived, along with the derived thermal conductivities, to provide a comprehensive description of hydrodynamics with dipolar anisotropy. An analysis of linear wave attenuation demonstrates the clear effect of anisotropy in dipolar fluids, dependent on the dipole orientation relative to the direction of wave propagation.