  When constructing high-order schemes for solving hyperbolic conservation
laws, the corresponding high-order reconstructions are commonly performed in
characteristic spaces to eliminate spurious oscillations as much as possible.
For multi-dimensional finite volume (FV) schemes, we need to perform the
characteristic decomposition several times in different normal directions of
the target cell, which is very time-consuming. In this paper, we propose a
rotated characteristic decomposition technique which requires only one-time
decomposition for multi-dimensional reconstructions. The rotated direction
depends only on the gradient of a specific physical quantity which is cheap to
calculate. This technique not only reduces the computational cost remarkably,
but also controls spurious oscillations effectively. We take a third-order
weighted essentially non-oscillatory finite volume (WENO-FV) scheme for solving
the Euler equations as an example to demonstrate the efficiency of the proposed
technique.
