Modeling multidimensional reactive flows during nova outbursts - achievements and challenges

Deviations from spherical symmetry are expected at the ignition and during the runaway of explosive hydrogen burning in a nova outburst. In all cases, the non-spherically symmetric effects are closely related to the coupling of convective flow with explosive nuclear burning and to the mixing and heating process of the relevant fuel. Those effects, which were analyzed in the past only by applying parametric and dimensional methods, can be carefully studied once the exact multidimensional equations are solved. Still, the restrictions of finite resolution and ranges of scales that can be included in the simulations should be taken into account. We present here the achievements we had up to now in our study, and we discuss the weak points related to the coupling between numeric effects and real physical phenomena, mainly concerning the mixing process. We introduce the method by which we try to get accurate quantitative results for the relevant physical quantities, such as the spreading time, the exact amount of mixing and the size and average structure of the convective zone.