Authors: Rohit Chhiber (NASA GSFC & U Delaware), Arcadi Usmanov (NASA GSFC & U Delaware), William Matthaeus (U Delaware), Yanwen Wang (U Maryland), Francesco Pecora (U Delaware), Melvyn Goldstein (Space Sci. Inst.)

Turbulence plays a significant role in solar wind dynamics, providing a mechanism
for in-situ heating and acceleration of the plasma. A fundamental parameter that arises in
turbulence modeling is the Reynolds stress, a statistical quantity that accounts for the effect of
fluctuations on mean momentum flow. In this work we employ a global solar wind model with
turbulence transport to present the first validation of the eddy-viscosity closure for the Reynolds
stress in the solar wind, by means of direct comparison with Parker Solar Probe observations. We
also examine the role played by the turbulent stress in the angular momentum dynamics of the
solar wind, and discuss implications for long-term solar rotational evolution.