Comparing Efficient Implicit Time-Stepping Techniques for Highly Resolved Simulations Using Industrial Geometries

High-fidelity modeling approaches such as LES are increasingly used for analyzing complex, unsteady flow phenomena in industrial geometries at high Reynolds numbers. However, their computational cost prevents widespread adoption as a standard tool in developing aerodynamic devices. One potential solution is to increase the simulation time step, even beyond the CFL limit, when employing implicit schemes to discretize the equations. Two implicit time-stepping techniques for solving the incompressible Navier-Stokes equations in a segregated manner using the high-order Spectral h/p element method were examined in this study. Our objectives were to explore the stability margins for each scheme, assess their impact on accuracy, and evaluate the achieved speed-up. The Imperial Front Wing (IFW) industrial benchmark was considered for these purposes. Both schemes successfully allowed for an increased simulation timestep, resulting in a considerable reduction in the total computation time. As the timestep increased, the flow accuracy deviated more from the reference simulation. This work outlines the characteristics of each scheme, compares them with existing literature on canonical flows, and highlights the trade-offs between accuracy and computational efficiency.