  Coronal mass ejections (CMEs) and their driven shocks are a major source of
large geomagnetic storms due to their large and long-lasting, southward
component of magnetic field in the sheath and the flux rope (e.g., magnetic
cloud). Predicting the strength and arrival time of southward fields accurately
thus plays a key role in space weather predictions. To address this problem, we
have developed a new model, which combines the global three-dimensional,
time-dependent, magnetohydrodynamic (MHD), data-driven model (G3DMHD) and a
self-contained magnetic flux-rope model [1]. As a demonstration and validation,
here we simulate the evolution of a Sun-Earth-directed CME that erupted on
2012-July-12. The computational domain spans from 2.5 solar radii (Rs) from the
surface of the Sun, where the flux rope is injected, to 245 Rs. We compare the
time profiles of the simulated MHD parameters (Density, velocity, temperature,
and magnetic field) with in situ solar wind observations acquired at ~1 AU by
the Wind spacecraft and the result is encouraging. The model successfully
reproduces the shock, sheath, and flux rope similar to those observed by Wind.
