Abstract
An improved domain‐decoupled compact scheme for first and second spatial derivatives is proposed for domain‐decomposition‐based parallel computational fluid dynamics. The method improves the accuracy of previously developed decoupled schemes and preserves the accuracy and bandwidth properties of fully coupled compact schemes, even for a very large degree of parallelism, and enables the Navier‐Stokes equations to be solved independently on each processor. The scheme is analysed using Fourier analysis and error analysis, and tested on one‐dimensional wave‐packet propagation, a two‐dimensional vortex convection problem, and in the direct numerical simulation of the three‐dimensional Taylor‐Green vortex problem and turbulent channel flow. Our results demonstrate the scheme's effectiveness in performing direct numerical simulation of turbulence in terms of accuracy and scalability.