High-order Spatial Schemes Research Articles

Grid density effect for numerical simulation of civil aircraft in post stall

Stall will deteriorate flight safety and cause serious accidents for civil aircraft. RANS-LES hybrid approaches have become a compromise choice due to insufficient ability of RANS for large flow separation. In present work, Zonal Detached-eddy-simulation coupled with high-order spatial scheme were employed to investigated grid density effect in the numerical simulations. The calculations show that the grid density would affect the numerical simulation of the small-scale flow structure in the wake of region of the main wing, and further affect the disturbance of main wing to the horizontal tail. It is necessary to properly densify the grid downstream of the main wing in order to accurately predict the aircraft stall.

High-order non-inertial computation method for helicopter rotor flows in forward flight

Purpose This paper aims to improve the computational efficiency and to achieve high-order accuracy for the computation of helicopter rotor unsteady flows in forward flight during the industrial preliminary design stage. Design/methodology/approach The integral arbitrary Lagrangian–Eulerian form of unsteady compressible Navier–Stokes equations with low Mach number preconditioned pseudo time terms based on non-inertial frame of reference undergoing rotating and translating was derived and discretized in the framework of multi-block structured finite volume grid using three types of spatial reconstruction schemes, i.e. the third-order accurate monotonic upwind scheme for conservation laws, the fifth-order accurate weighted essentially non-oscillatory and the fifth-order accurate weighted compact nonlinear schemes. Findings The results show that the present non-inertial computational method can obtain comparable results with other methods, such as the dynamic overset method, and make sure that the higher-order spatial schemes can significantly improve the tip vortex resolution. Originality/value The computational grid used by the present method remained static during the whole unsteady computation process, with only local deformations induced by blade cyclic pitch and other operating motions, which greatly reduced the complexity of grid motion and enhanced the efficiency and robustness.

FDTD Algorithm for Microstrip Antennas with Lossy Substrates Using Higher Order Schemes

Higher order spatial schemes are applied to approximate the derivatives of the conducting Maxwell's equations and an analytical study regarding the stability properties and the numerical dispersion of the N-order-in-space and second-order-in-time technique is considered. The hard-to-model effect of dielectric losses on microstrip antennas is investigated and their performance is demonstrated using a fourth-order-in-space and second-order-in-time, finite-difference time-domain scheme in three-dimensional calculations.