  One of the important discoveries made by Voyager-2 is the nonadiabatic radial
profile of the solar wind proton temperature. This phenomenon has been studied
for several decades. The dissipation of turbulence energy has been proposed as
the main physical process responsible for the temperature profile. The
turbulence is both convected with the solar wind and originated in the solar
wind by the compressions and shears in the flows and by pick-up ions. The
compression source of the solar wind heating in the outer heliosphere appears
due to shock waves, which originated either in the solar corona or in the solar
wind itself. The goal of this work is to demonstrate that the shock-wave
heating itself is enough to explain the temperature profile obtained by
Voyager-2. The effect of shock-wave heating is demonstrated in the frame of a
very simple spherically symmetric high-resolution (in both space and time)
gas-dynamical data-driven solar wind model. This data-driven model employs the
solar-wind parameters at 1 AU with minute resolution. The data are taken from
the NASA OMNIWeb database. It is important to underline that (1) the model
captures the shocks traveling and/or originating in the solar wind, and (2)
other sources of heating are not taken into account in the model. We extended
this simple model to the magnetohydrodynamic (MHD) and two-component models and
found very similar results. The results of the numerical modeling with the
one-minute OMNI data as the boundary condition show very good agreement with
the solar-wind temperature profiles obtained by Voyager-2. It is also
noteworthy that the numerical results with daily averaged OMNI data show a very
similar temperature profile, while the numerical runs with 27-day-averaged OMNI
data demonstrate the adiabatic behavior of the temperature.
