A new high order hybrid WENO scheme for hyperbolic conservation laws

This article proposes an improved hybrid weighted essentially non-oscillatory (WENO) scheme based on the third- and fifth-order finite-difference modified WENO (MWENO) schemes developed by Zhu et al. in (SIAM J. Sci. Comput. 39 (2017), A1089-A1113.) for solving hyperbolic conservation laws. The MWENO schemes give a guideline on whether to use the WENO scheme or the linear upwind scheme. Unfortunately, because there is no explicit formula for computing the roots of algebraic polynomials of order four or higher, it is difficult to generalize this criterion to higher order cases. Therefore, this article proposes a simple criterion for constructing a series of seventh-, ninth-, and higher-order hybrid WENO schemes, and then designs a class of improved smooth indicator WENO (WENO-MS) schemes. Compared with the classical WENO schemes, the main advantages of the WENO-MS schemes are their robustness and efficiency. And these WENO-MS schemes are more efficient, have better resolution, and can solve many extreme problems without any additional techniques. Furthermore, a simplification criterion is proposed to further improve the computational efficiency of the WENO-MS schemes, and these simple WENO-MS schemes are abbreviated as WENO-SMS schemes in this article. Extensive numerical results demonstrate the good performance of the WENO-MS schemes and the WENO-SMS schemes.