  We present a new multi-fluid, grid MHD code PIERNIK, which is based on the
Relaxing TVD scheme (Jin & Xin, 1995). The original scheme (see Trac & Pen
(2003) and Pen et al. (2003)) has been extended by an addition of dynamically
independent, but interacting fluids: dust and a diffusive cosmic ray gas,
described within the fluid approximation, with an option to add other fluids in
an easy way. The code has been equipped with shearing-box boundary conditions,
and a selfgravity module, Ohmic resistivity module, as well as other facilities
which are useful in astrophysical fluid-dynamical simulations. The code is
parallelized by means of the MPI library. In this paper we present Ohmic
resistivity extension of the original Relaxing TVD MHD scheme, and show
examples of magnetic reconnection in cases of uniform and current-dependent
resistivity prescriptions.
