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Abstract. We report on an international effort to develop an open-source computational environment for high-fidelity fluid-structure interaction analysis. In particular, we will focus on verification of the implementation for application in computational aeroelasticity. The capabilities of the SU2 code for aeroelastic analysis have been further enhanced both by developing natively embedded tools for the study of largely deformable solids, and by wrapping it using Python tools for an improved communication with external solvers. Both capabilities will be demonstrated on relevant test cases, including rigid-airfoil solutions with indicial functions, the Isogai Wing Section, test cases from the AIAA 2nd Aeroelastic Prediction Workshop, and the vortex-induced vibrations of a flexible cantilever in the wake of a square cylinder. Results show very good performance both in terms of accuracy and computational efficiency. The modularity and versatility of the baseline suite allows for a flexible framework for multidisciplinary computational analysis. The software libraries have been freely shared with the community to encourage further engagement in the improvement, validation and further development of this open-source project.

Abstract. By analogy with the kinetic theory of gases, most turbulence modeling strategies rely on an eddy viscosity to model the unresolved turbulent fluctuations. However, the ratio of unresolved to resolved scales -very much like a degree of rarefaction -is not taken into account by the popular conventional schemes, based on the NavierStokes equations. This paper investigates the simulation of turbulent flow with a gaskinetic scheme. In so doing, the modeling of turbulence becomes part of the numerical scheme: the degree of rarefaction is automatically taken into account; the turbulent stress tensor is not constrained into a linear relation with the strain rate. Instead it is modeled on the basis of the analogy between particles and eddies, without any assumptions on the type of turbulence or flow class. The implementation of a turbulent gas-kinetic scheme into a finite-volume solver is put forward, with turbulent kinetic energy and dissipation supplied by an allied turbulence model. A number of flow cases, challenging for conventional RANS methods, are investigated; results show that the shock-turbulent boundary layer is captured in a much more convincing way by the gas-kinetic scheme.

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Gas-kinetic theory is also valid in the continuum regime: the Euler and Navier-Stokes equations can be obtained as projection of the Boltzmann equation on to the physical space (x,t). The numerical schemes derived from gas-kinetic theory are computationally more expensive than Navier-Stokes based ones, but offer advantages which have been attracting a growing level of attention: they can (i) accommodate discontinuities at cells interface, (ii) provide high-resolution fluxes, (iii) provide advantages in the simulation of turbulence, (iv) handle hypersonic and/or rarefied flows. This study extends the validation of gas-kinetic schemes investigating a few turbulent flow cases. At a slightly higher computational cost, gas-kinetic schemes provide results comparable to those obtained with well-validated Navier-Stokes schemes using the same turbulence model, grid and reconstruction order. In the case of shock-separated flows, the results obtained with the gas-kinetic scheme are even closer to experimental data. These findings are consistent with the idea that gas-kinetic theory is a physically more consistent framework for investigating the mechanics of fluids.