Numerical simulations of flux-tube dynamics and some other astrophysical problems will be presented. The simulations are performed with the versatile advection code, VAC.
VAC is a general tool for modeling typical astrophysical MHD and hydro-dynamical problems. The code allows the user to solve a system of partial differential equations with a variety of modern high resolution numerical schemes on 1, 2 or 3D grids with generalized coordinates. In 1D and 2D both slab and axial symmetry are supported, and vector variables can have more components than the number of spatial dimensions of the grid, which is usually referred to as 1.5D or 2.5D simulations. The equations may contain fluxes and source terms. Compressible hydrodynamics with adiabatic or full energy equation and the ideal/resistive MHD equations with isothermal or full energy equation are all implemented. A projection scheme can keep the divergence of the magnetic field negligible. The boundary and initial conditions can be chosen from a number of predefined types, but the code is structured in a manner that allows the user to write his/her own subroutines for new types of boundary or initial conditions. The choice of algorithms allows the user to find the optimal one for the application at hand and/or to compare results of different schemes thus gaining insight into the numerical effects. An emphasis is put on independence of computer platforms, thus the code can be translated to Fortran 90, Fortran 77 or CMFortran languages before compilation. Efficiency of the code is also a high priority, the options available for the user do not compromise the performance.