Numerical Simulations of Solar Active Phenomena at the Astronomical Institute of Romanian Academy Cristiana Dumitrache Astronomical Institute of the Romanian Academy, Bucharest, Romania, e-mail: crisd@aira.astro.ro Abstract. The MHD numerical simulations started to be performed at the Astronomical Institute of Romanian Academy eleven years ago. We present here the main results obtained during this period. The 2D numerical experiments were performed by the Alfvén code. We have obtained the main active phenomena of the solar activity: flares, prominences, CMEs, coronal streamers and coronal holes. Keywords: numerical simulations, corona, prominences, CME, coronal streamer, current sheet PACS: 95.75.-z, 90.60 INTRODUCTION The dynamics of solar corona offer a wide and spectacular types of phenomena. The magnetic structures play an important role in the solar atmosphere dynamics. Energy storage and dynamics affect structures as large as transequatorial loops, while the re- lease process probably occurs on the minuscule scales of current sheets and nulls. The current sheets form naturally in the solar atmosphere and their are sites of flares, promi- nences and other coronal structures formation. The current sheets play a central role in explosive phenomena such as flares, jets, and CMEs, i.e., fast magnetic reconnection. Other interesting magnetic configuration as initial configuration is the complex poten- tial. We present here a review of the solar MHD numerical simulations performed at the Astronomical Institute of Romanian Academy in the last eleven years. This type of re- searches started in our country in 1995, when our Institute purchased a superscalar com- puter (Silicon Graphics Power Challenge M), one processor R 8,000 64 Mb RAM, 2 (b secondary cache, speed 300 M flops). We have used the Alfvén code based on SHASTA method described in [1] and [2]. For numerical reason, we have considered η = 10 −3 and a computational grid with low resolution in the most experiments. Our simulations focused especially on the phenomenology and comparison with the observed features. We will summarize some ideas we have learned from these numerical experiments. EQUATIONS AND INITIAL CONFIGURATIONS We have integrated the MHD equations in a 2D frame situated in the solar meridian plane, taking into account the gravitation.