Calculations of Unsteady Flow and Flutter by an Euler and Integral Boundary-Layer Method on Cartesian Grids

This paper presents an Euler and boundary-layer method capable of unsteady flow and aeroelastic simulations. An integral boundary-layer solver is coupled with an Euler solver in a “semi-inverse” manner. For the inviscid part, approximate wall boundaryconditions are implemented on non-moving mean chord positions, whereas the full nonlinear Euler equation is solved in the field for accurate resolution of shock waves and vorticity. Stationary Cartesian grids are used for both steady and unsteady calculations. An integral boundary-layer method using Green’s lag equation is coupled with the outer inviscid flow. Results of steady and unsteady calculations by this interactive boundary-layer method are presented and compared with experimental data. Flutter-boundary predictions for the 2D Isogai wing model are provided and compared with results using the Euler solver without the boundary-layer corrections and also thin-layer Navier-Stokes results. It shows that viscous effects are significant for this case.