High-fidelity aeroelastic simulation of flexible wings inseparated flows
Creators: name: Lahooti, Mohsen
name: Palacios, Rafael
name: Sherwin, Spencer
Publisher: name: Zenodo
Year: 2021
Subjects: fluid structure interaction, FSI, high-fidelity simulation, LES, DNS, aeroelasticity, wind turbine, wind energy

description: An efficient high-fidelity FSI method is developed for aeroelastic simulations of highly deformable streamlined<br> structures in separated flows with a non-constant cross-section over the structure span. The method is the further<br> development of our Nektar++/SHARPy FSI solver [1] to support non-constant sectional geometry over the<br> structural span as well as introducing correction factor for tip loss effect. The FSI solver has implemented in<br> Nektar++ [2] framework where the Navier-Stokes equation is discretized and solved using the high-order<br> spectral/hp element method. Large-Eddy Simulation (LES) method is used to resolve the turbulent structures in<br> highly separated flow condition and accurately predict the fluid forces on the structure. To reduce the<br> computational cost of LES simulation over the slender structure, the thick-strip method [3] is adopted where the<br> full 3D fluid domain is represented with series of separated smaller domains, each of which has a finite thickness<br> in the spanwise direction. Having the finite thickness for the strips enables capturing local 3D wake turbulent<br> while representing the full 3D domain with a finite number of smaller domains reduces the overall computational<br> cost of LES simulation over the slender structure. The thick strips are separated domains that implicitly connected<br> via the structural dynamics. Hence, a correction factor based on the calculated circulation in each strip is<br> introduced to take into account the tip-loss effect. To support independent geometry and meshes for each strip,<br> the hybrid parallelism approach [4] of Nektar++ is further modified which enable having non-constant cross-<br> sections over the span. Large-deformation dynamics of the structure is modelled using a geometrically-exact<br> composite beam finite-element model [5]. Simulation results of deformation of NREL5 MW reference wind<br> turbine blade [6] in high angle of attack with large separating flow over the blade is presented and the<br> computational challenges and requirements for such simulations are discussed in the present research.<br> REFERENCES<br> [1] M. Lahooti and R. Palacios and S.J. Sherwin, “Thick Strip Method for Efficient Large-Eddy Simulations of Flexible<br> Wings in Stall”. In AIAA Scitech 2021 Forum,p. 0363 (2021).<br> [2] D. Moxey and C.D. Cantwell and Y. Bao and A. Cassinelli and G. Castiglioni and S. Chun and E. Juda and E. Kazemi,<br> and K. Lackhove and J. Marcon and G.Mengaldo, “Nektar++: Enhancing the capability and application of high-fidelity<br> spectral/hp element methods”. Compu. Phys. Commu., 249, p.107110 (2020).<br> [3] Y. Bao and R. Palacios and M. Graham and S. Sherwin, “Generalized thick strip modelling for vortex-induced<br> vibration of long flexible cylinders”. J Comput. Phys, 321, pp.1079-1097. (2016).<br> [4] A. Bolis, Fourier spectral/hp element method: investigation of time-stepping and parallelisation strategies, PhD<br> dissertation, Imperial College London, (2012).<br> [5] A. del Carre and A. Muñoz-Simón and N. Goizueta and R. Palacios, “SHARPy: A dynamic aeroelastic simulation<br> toolbox for very flexible aircraft and wind turbines.”, J. Open Source Softw., 4(44), p.1885. (2019)<br> [6] J. Jonkman and S. Butterfield and W. Musial and G. Scott., “Definition of a 5-MW reference wind turbine for offshore<br> system development (No. NREL/TP-500-38060).”, National Renewable Energy Lab.(NREL), Golden, CO, United States,<br> (2009)
description: My presentation slides at Coupled 2021