MODELLING THE SUN AND STARS IN 3-D

Stars can be seen as modern physics laboratory from which fundamental processes as diverse as atomic physics or turbulence can be studied and understood. Being able to model accurately their structure, dynamic and evolution is thus of fundamental importance and is the subject of intense research. In this short review we will present some of the numerical simulations in three dimensions performed in recent years to model such complex and nonlinear objects, focussing mostly our discussion on results obtained with the anelastic spherical harmonic (ASH) code. Using the Sun as a reference star, we wish to gain insight and to constrain magnetohydrodynamical processes (such as Reynolds and Maxwell stresses, meridional circulations, differential rotation (i.e. omega-effect), thermal wind, alpha-effect) at the origin of the solar small and large scale dynamics and magnetism. We will then extend our study to other stars, such as young Suns, massive stars or evolved RGB stars in order to identify which processes are at the origin of their significantly different dynamics.