2015/11/21 by Chaitanya Talnikar, Talnikar, Chaitanya, Qiqi Wang +3 · 2 citations
Engineering · #Computational Fluid Dynamics and Aerodynamics #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Turbomachinery Performance and Optimization
paper · pdf · doi:10.48550/arxiv.1511.06959
openalex publication_date 2015/11/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
High fidelity simulations, e.g., large eddy simulation are often needed for\naccurately predicting pressure losses due to wake mixing in turbomachinery\napplications. An unsteady adjoint of such high fidelity simulations is useful\nfor design optimization in these aerodynamic applications. In this paper we\npresent unsteady adjoint solutions using a large eddy simulation model for a\nvane from VKI using aerothermal objectives. The unsteady adjoint method is\neffective in capturing the gradient for a short time interval aerothermal\nobjective, whereas the method provides diverging gradients for long\ntime-averaged thermal objectives. As the boundary layer on the suction side\nnear the trailing edge of the vane is turbulent, it poses a challenge for the\nadjoint solver. The chaotic dynamics cause the adjoint solution to diverge\nexponentially from the trailing edge region when solved backwards in time. This\nresults in the corruption of the sensitivities obtained from the adjoint\nsolutions. An energy analysis of the unsteady compressible Navier-Stokes\nadjoint equations indicates that adding artificial viscosity to the adjoint\nequations can potentially dissipate the adjoint energy while potentially\nmaintain the accuracy of the adjoint sensitivities. Analyzing the growth term\nof the adjoint energy provides a metric for identifying the regions in the flow\nwhere the adjoint term is diverging. Results for the vane from simulations\nperformed on the Titan supercomputer are demonstrated.\n