Low-friction fluid flow surface design using topology optimization
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RESEARCH PAPER
Low-friction fluid flow surface design using topology optimization Eduardo Tadashi Katsuno1
˜ Lucas Dozzi Dantas2 · Joao
· Em´ılio Carlos Nelli Silva1
Received: 29 November 2019 / Revised: 3 July 2020 / Accepted: 28 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Several practical applications in fluid mechanics have the interest to reduce energy dissipation by reducing the drag or pressure drop. An example of a solution is to turn the wetted surface into a super-hydrophobic surface (SHS). However, the whole surface coated may adversely affect some regions, depreciating the fluid flow. Furthermore, an SHS may not be cheap, being important to decide which regions to prioritize. Thus, in this work, the topology optimization method is applied to obtain an optimized design of SHS distribution. Derivation of the discrete adjoint problem applied to super-hydrophobic modeling is shown. The numerical implementation is done by using a computational fluid dynamics (CFD) code based on the finite volume method (FVM) as the primal and the adjoint solver, and the internal point optimization algorithm (IPOPT) as the optimizer. The SHS behavior is simplified by adopting the slip length model. Two test cases are presented: internal and external flows. For internal flow case, a stretched-S pipe is used, aiming to reduce the pressure drop; for external flow case, the foil NACA0015 is analyzed, aiming to reduce the drag. Both cases are assumed to be 2D, steady-state flow, using the properties of water, in a fully turbulent flow, and constrained by a maximum material distribution. Optimized topologies for several surface constraints (maximum amount of SH material used) are obtained, showing the regions to be prioritized based on the surface constraint limit. Additionally, the effects of slip length (the level of hydrophobicity), Reynolds number, and angle of attack are analyzed. The obtained results show that regions to be prioritized in order to reduce the dissipated energy are not always intuitive. Furthermore, depending on the operating condition, a fully SHS case may not be the best option. Keywords Topology optimization · High Reynolds flow · Computational fluid dynamics (CFD) · Super-hydrophobic surface (SHS) · Finite volume method (FVM)
1 Introduction In many practical applications in fluid mechanics, it is common to have the interest to reduce energy dissipation by reducing the drag or pressure drop. After increased Responsible Editor: Seonho Cho Em´ılio Carlos Nelli Silva
[email protected] Eduardo Tadashi Katsuno [email protected] Jo˜ao Lucas Dozzi Dantas [email protected] 1
Department of Mechatronics and Mechanical Systems Engineering, Escola Polit´ecnica - University of S˜ao Paulo, 2231, Prof. Mello Moraes Ave., 05508-030, S˜ao Paulo, Brazil
2
Naval Architecture and Ocean Engineering Laboratory, IPT - Institute for Technological Research, 532, Prof. Almeida Prado Ave., 05508-901, S˜ao Paulo, Brazil
concern in the emission of greenhouse gases, saving energy consumption
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