  As the representative of the shock-capturing scheme, the Roe scheme fails to
LES because important turbulent characteristics cannot be reproduced such as
the famous k-5/3 spectral law owing to large numerical dissipation. In this
paper, the Roe scheme is divided into five parts: , , , , and , which means
basic upwind dissipation, pressure-difference-driven and
velocity-difference-driven modification of the interface fluxes and pressure,
respectively. Then, the role of each part on LES is investigated by homogeneous
decaying turbulence. The results show that the parts , , and have little effect
on LES. It is important especially for because it is necessary for computation
stability. The large numerical dissipation is due to and , and each of them has
much larger dissipation than SGS dissipation. According to these understanding,
an improved all-speed LES-Roe scheme is proposed, which can give enough good
LES results for even coarse grid resolution with usually adopted
reconstruction.
