This study performs numerical analyses for two different working fluids. One is an analysis of natural convection using a model with air that is compared with the results of applied experiments. Then, it can be used to investigate the pattern of natural convection in concentric spheres. The other is an investigation for the relationship between velocity field, electromagnetic field, and temperature field in a model with molten metal. The subject of the analysis model is the natural convection between two concentric spherical shells. In particular, a process where induced magnetic fields intensify the imposed magnetic field can be called a dynamo process. This study uses a modified B method in order to investigate the role of this induced magnetic field. This method is also compared to a ${Phi}$ method that only considers imposed magnetic fields. In addition, this study examines the relationship between the velocity field and the electromagnetic field for the velocity field through applying Coriolis forces.