  With the recent results of helioseismology aboard SOHO, solar models are more
and more constrained (Brun, Turck-Chieze and Morel 1998 (astro-ph/9806272)).
New physical processes, mainly connected to macroscopic motions, must be
introduced to understand these new observations. In this poster, we present
solar models including a turbulent pressure in the outer layers and mixing due
to the tachocline (Spiegel and Zahn 1992). Our results lead us to conclude
that: - Turbulent pressure improves the absolute value of the acoustic mode
frequencies (~ 10 microHz at 4mHz), - Mixing in a tachocline thickness of 0.05
+/- 0.03 Ro (Corbard et al. 1997) looks promising.
