Shaoshuai Chu

Shaoshuai Chu, Michael Herty

We develop high-order numerical schemes to solve random hyperbolic conservation laws using linear programming. The proposed schemes are high-order extensions of the existing first-order scheme introduced in [{\sc S. Chu, M. Herty, M. Lukáčová-Medvi{\softd}ová, and Y. Zhou}, SIAM J. Sci. Comput., 48 (2026)], where a novel structure-preserving numerical method using a concept of generalized, measure-valued solutions to solve random hyperbolic systems of conservation laws is proposed, yielding a linear partial differential equation concerning the Young measure and allowing the computation of approximations based on linear programming problems. The second-order extension is obtained using piecewise linear reconstructions of the one-sided point values of the unknowns. The fifth-order scheme is developed using the finite-difference alternative weighted essentially non-oscillatory (A-WENO) framework. These extensions significantly improve the resolution of discontinuities, as demonstrated by a series of numerical experiments on both random (Burgers equation, isentropic Euler equations) and deterministic (discontinuous flux, pressureless gas dynamics, Burgers equation with non-atomic support) hyperbolic conservation laws.

Shaoshuai Chu, Igor Kliakhandler, Alexander Kurganov

We introduce new adaptive artificial anti-diffusion (AAAD) methods for one- and two-dimensional hyperbolic systems of conservation laws. The key idea is to reduce the amount of numerical dissipation present in a given numerical method by adding an anti-diffusion (AD) term acting in linearly degenerate fields only. This way, the resolution of contact waves can be improved without risking oscillations, which may be caused if the AD acts in nonlinear fields as well. The AD coefficients are selected adaptively: they are supposed to be proportional to the mesh size near the contact waves to enhance the resolution and to be very small in the smooth parts of the computed solution to ensure a sufficiently high (formal) order of accuracy there. The proposed AAAD methods are realized using either the second-order central-upwind numerical fluxes or their fifth-order extensions implemented within the alternative weighted essentially non-oscillatory (A-WENO) framework. We test the proposed schemes on a series of benchmarks for the one- and two-dimensional Euler equations of gas dynamics and the obtained results demonstrate the robustness and high resolution of the new AAAD methods.

Shaoshuai Chu, Pingyao Feng, Vadim A. Kolotilov et al.

We introduce new adaptive schemes for the one- and two-dimensional hyperbolic systems of conservation laws. Our schemes are based on an adaption strategy recently introduced in [{\sc S. Chu, A. Kurganov, and I. Menshov}, Appl. Numer. Math., 209 (2025)]. As there, we use a smoothness indicator (SI) to automatically detect ``rough'' parts of the solution and employ in those areas the second-order finite-volume low-dissipation central-upwind scheme with an overcompressive limiter, which helps to sharply resolve nonlinear shock waves and linearly degenerate contact discontinuities. In smooth parts, we replace the limited second-order scheme with a quasi-linear fifth-order (in space and third-order in time) finite-difference scheme, recently proposed in [{\sc V. A. Kolotilov, V. V. Ostapenko, and N. A. Khandeeva}, Comput. Math. Math. Phys., 65 (2025)]. However, direct application of this scheme may generate spurious oscillations near ``rough'' parts, while excessive use of the overcompressive limiter may cause staircase-like nonphysical structures in smooth areas. To address these issues, we employ the same SI to distinguish contact discontinuities, treated with the overcompressive limiter, from other ``rough'' regions, where we switch to the dissipative Minmod2 limiter. Advantage of the resulting adaptive schemes are clearly demonstrated on a number of challenging numerical examples.

Shaoshuai Chu, Michael Herty, Alexander Kurganov

We introduce a new scheme adaption strategy for one- and two-dimensional hyperbolic systems of conservation laws. The proposed approach builds upon the adaptive framework introduced in [S. Chu, A. Kurganov, and I. Menshov, Appl. Numer. Math., 209 (2025), pp.155--170], where we first employed the smoothness indicator from [R. Lohner, Comput. Methods. Appl. Mech. Eng., 61 (1987), pp.323--338] to automatically detect ``rough'' and smooth parts of the computed solution, and then used different limiters in the detected regions. This adaptive strategy was based on a threshold needed to sharply separate ``rough'' and smooth regions. In this paper, we propose a different adaption strategy. We use SBM-type limiters and vary one of the limiting parameters continuously to allow a smooth transition between the ``rough'' and smooth areas. This way, compressive and overcompressive limiters are activated in the shock and contact wave vicinities only, while we gradually switch to dissipative limiters in the smooth regions. A series of one- and two-dimensional numerical tests for the Euler equations of gas dynamics demonstrates that the new scheme adaption strategy leads to a higher resolution and reduced numerical dissipation.