Implementation of all‐Mach Roe‐type schemes in fully implicit CFD solvers – demonstration for wind turbine flows

This paper presents the implementation of all‐Mach Roe‐type schemes in a fully implicit CFD solver. Simple 2D cases, such as the flow around inviscid and viscous aerofoils, were used for an initial validation of these methods, along with more challenging computations consisting of the 3D flow around the Model Experiments in Controlled Conditions wind turbine, in parked and rotating conditions. This work is motivated by the increased interest of the wind turbine industry in larger diameter wind turbines where compressibility effects near the blade tips may be important. Instead of using an incompressible flow solver, this paper explores the option of modifying an existing, efficient, compressible flow solver for use at lower Mach numbers. The good performance of the Roe solver and its popularity influenced the selection of schemes for this work. The results suggest that effective all‐Mach solutions are possible with implicit solvers, and the paper defines the implementation of the new fluxes and Jacobian, including an investigation of some numerical parameters, using as platform the Helicopter Multi‐Block solver of Liverpool University. Copyright © 2013 John Wiley & Sons, Ltd.