exaFOAM Workshop June 2023 - Compression Methods for Adjoint-based Optimization of Unsteady Flows

Talk held by Kyriakos Giannakoglou, NTUA in the exaFOAM Workshop about Compression Methods for Adjoint-based Optimization of Unsteady Flow Problems. In gradient-based aerodynamic optimization, assisted by the adjoint approach, is the state-of-the-art for computing gradients of an objective function (e.g. lift/drag forces) w.r.t. the design variables parameterizing an aerodynamic shape (e.g. car, aircraft). Utilizing the adjoint approach in transient flow problems, like the ones related to high fidelity turbulence models (DES, LES) typically used in HPC environments, requires the solution of an additional set of PDEs, derived by the Navier-Stokes equations but solved backwards in time. This poses the problem of storing all flow field instances during the solution of the unsteady Navier-Stokes equations, to be then used in the solution of the adjoint PDEs. Compressing the primal solution time-series is extremely beneficial both memory-wise and cost-wise.