Hostname: page-component-77c89778f8-7drxs Total loading time: 0 Render date: 2024-07-17T05:19:35.380Z Has data issue: false hasContentIssue false

Geometrically weighted modal decomposition techniques

Published online by Cambridge University Press:  29 January 2021

Tso-Kang Wang
Affiliation:
Department of Mechanical Engineering, Joint College of Engineering Florida State University-Florida A&M University, Tallahassee, FL32310, USA
Kourosh Shoele*
Affiliation:
Department of Mechanical Engineering, Joint College of Engineering Florida State University-Florida A&M University, Tallahassee, FL32310, USA
*
Email address for correspondence: kshoele@eng.famu.fsu.edu

Abstract

Modal decomposition techniques have become important mathematical methodologies in analysing complex flow physics. The data-driven methods, such as proper orthogonal decomposition and dynamic mode decomposition are used to extract coherent structures in the form of spatial modes. These methods can be applied to both numerical and experimental data to identify the characteristic dynamics of the system. However, the classical data-driven modal decomposition methods are only applicable to problems with a fixed shape and are not suitable for systems with fluid–structure interaction or systems with shape-changing geometries. In this paper we propose a novel method utilizing a conformal mapping technique to solve this issue. Through different examples with deforming geometry, the capability of the method to accurately capture the flow features is demonstrated. The proposed method is found to be suitable for a wide range of applications and a possible candidate for reduced-order flow modelling of complex shape-changing systems.

Type
JFM Papers
Copyright
© The Author(s), 2021. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Afanasiev, K. & Hinze, M. 2001 Adaptive control of a wake flow using proper orthogonal decomposition. In Shape Optimization And Optimal Design (ed. Polis, M.P., Cagnol, J. & Zolésio, J.-P.), chap. 13. CRC Press.Google Scholar
Anttonen, J.S.R., King, P.I. & Beran, P.S. 2003 POD-based reduced-order models with deforming grids. Math. Comput. Model. 38 (1–2), 4162.CrossRefGoogle Scholar
Astrid, P., Weiland, S., Willcox, K. & Backx, T. 2008 Missing point estimation in models described by proper orthogonal decomposition. IEEE Trans. Autom. Control 53 (10), 22372251.CrossRefGoogle Scholar
Aubry, N., Holmes, P., Lumley, J.L. & Stone, E. 1988 The dynamics of coherent structures in the wall region of a turbulent boundary layer. J. Fluid Mech. 192, 115173.CrossRefGoogle Scholar
Batchelor, G.K. 2000 An Introduction to Fluid Dynamics. Cambridge Mathematical Library, Cambridge University Press.CrossRefGoogle Scholar
Bazilevs, Y., Takizawa, K. & Tezduyar, T.E. 2013 Challenges and directions in computational fluid–structure interaction. Math. Models Methods Appl. Sci. 23 (02), 215221.CrossRefGoogle Scholar
Beal, D.N., Hover, F.S., Triantafyllou, M.S., Liao, J.C. & Lauder, G.V. 2006 Passive propulsion in vortex wakes. J. Fluid Mech. 549, 385402.CrossRefGoogle Scholar
Beg, M.F., Miller, M.I., Trouvé, A. & Younes, L. 2005 Computing large deformation metric mappings via geodesic flows of diffeomorphisms. Intl J. Comput. Vis. 61 (2), 139157.CrossRefGoogle Scholar
Blake, R.W. 1983 Fish Locomotion. CUP Archive.Google Scholar
Blevins, R.D. 1977 Flow-Induced Vibration. Van Nostrand Reinhold Co.Google Scholar
Borazjani, I. & Sotiropoulos, F. 2008 Numerical investigation of the hydrodynamics of carangiform swimming in the transitional and inertial flow regimes. J. Expl Biol. 211 (10), 15411558.CrossRefGoogle ScholarPubMed
Bozkurttas, M., Dong, H., Mittal, R., Madden, P. & Lauder, G. 2006 Hydrodynamic performance of deformable fish fins and flapping foils. In 44th AIAA Aerospace Sciences Meeting and Exhibit, p. 1392. AIAA.CrossRefGoogle Scholar
Bozkurttas, M., Mittal, R., Dong, H., Lauder, G.V. & Madden, P. 2009 Low-dimensional models and performance scaling of a highly deformable fish pectoral fin. J. Fluid Mech. 631, 311342.CrossRefGoogle Scholar
Bragg, M.B., Gregorek, G.M. & Lee, J.D. 1986 Airfoil aerodynamics in icing conditions. J. Aircraft 23 (1), 7681.CrossRefGoogle Scholar
Cao, Y., Miller, M.I., Winslow, R.L. & Younes, L. 2005 Large deformation diffeomorphic metric mapping of vector fields. IEEE Trans. Med. Imaging 24 (9), 12161230.Google ScholarPubMed
Cesur, A., Carlsson, C., Feymark, A., Fuchs, L. & Revstedt, J. 2014 Analysis of the wake dynamics of stiff and flexible cantilever beams using POD and DMD. Comput. Fluids 101, 2741.CrossRefGoogle Scholar
Childress, S., Vandenberghe, N. & Zhang, J. 2006 Hovering of a passive body in an oscillating airflow. Phys. Fluids 18 (11), 117103.CrossRefGoogle Scholar
Christensen, E.A., Brøns, M. & Sørensen, J.N. 1999 Evaluation of proper orthogonal decomposition–based decomposition techniques applied to parameter-dependent nonturbulent flows. SIAM. J. Sci. Comput. 21 (4), 14191434.CrossRefGoogle Scholar
Clarke, A. & Johnston, N.M. 1999 Scaling of metabolic rate with body mass and temperature in teleost fish. J. Animal Ecol. 68 (5), 893905.CrossRefGoogle Scholar
Connell, B.S.H. & Yue, D.K.P. 2007 Flapping dynamics of a flag in a uniform stream. J. Fluid Mech. 581, 3367.CrossRefGoogle Scholar
Ding, H., Shu, C., Yeo, K.S. & Xu, D. 2007 Numerical simulation of flows around two circular cylinders by mesh-free least square-based finite difference methods. Intl J. Numer. Meth. Fluids 53 (2), 305332.CrossRefGoogle Scholar
Dong, G.-J. & Lu, X.-Y. 2007 Characteristics of flow over traveling wavy foils in a side-by-side arrangement. Phys. Fluids 19 (5), 057107.CrossRefGoogle Scholar
Eames, I. 2008 Rapidly dissolving dense bodies in an inviscid fluid. Proc. R. Soc. A 464 (2099), 29853002.CrossRefGoogle Scholar
Eldredge, J.D. 2007 Numerical simulation of the fluid dynamics of 2D rigid body motion with the vortex particle method. J. Comput. Phys. 221 (2), 626648.CrossRefGoogle Scholar
Eldredge, J.D. 2019 Mathematical Modeling of Unsteady Inviscid Flows. Springer.CrossRefGoogle Scholar
Eldredge, J.D. & Pisani, D. 2008 Passive locomotion of a simple articulated fish-like system in the wake of an obstacle. J. Fluid Mech. 607, 279288.CrossRefGoogle Scholar
Flanders, H. 1966 Liouville's theorem on conformal mapping. J. Maths Mech. 15 (1), 157161.Google Scholar
Floater, M.S. & Hormann, K. 2005 Surface parameterization: a tutorial and survey. In Advances in Multiresolution for Geometric Modelling (ed. N.A. Dodgson, M.S. Floater & M.A. Sabin), pp. 157–186. Springer.CrossRefGoogle Scholar
Fogleman, M., Lumley, J., Rempfer, D. & Haworth, D. 2004 Application of the proper orthogonal decomposition to datasets of internal combustion engine flows. J. Turbul. 5 (23), 13.CrossRefGoogle Scholar
Freno, B.A & Cizmas, P.G.A. 2014 A proper orthogonal decomposition method for nonlinear flows with deforming meshes. Intl J. Heat Fluid Flow 50, 145159.CrossRefGoogle Scholar
Gero, D.R., et al. . 1952 The hydrodynamic aspects of fish propulsion. American Museum Novitates; no. 1601.Google Scholar
Gillooly, J.F., Brown, J.H., West, G.B., Savage, V.M. & Charnov, E.L. 2001 Effects of size and temperature on metabolic rate. Science 293 (5538), 22482251.CrossRefGoogle ScholarPubMed
Gotsman, C., Gu, X. & Sheffer, A. 2003 Fundamentals of spherical parameterization for 3D meshes. In ACM Transactions on Graphics (TOG), vol. 22, pp. 358–363. ACM.CrossRefGoogle Scholar
Goza, A. & Colonius, T. 2018 Modal decomposition of fluid–structure interaction with application to flag flapping. J. Fluids Struct. 81, 728737.CrossRefGoogle Scholar
Gray, J. 1933 Studies in animal locomotion: I. The movement of fish with special reference to the EEL. J. Expl Biol. 10 (1), 88104.Google Scholar
Gu, X., Wang, Y., Chan, T.F., Thompson, P.M. & Yau, S.-T. 2004 Genus zero surface conformal mapping and its application to brain surface mapping. IEEE Trans. Med. Imaging 23 (8), 949958.CrossRefGoogle ScholarPubMed
Guglielmini, L. & Blondeaux, P. 2004 Propulsive efficiency of oscillating foils. Eur. J. Mech. B/Fluids 23 (2), 255278.CrossRefGoogle Scholar
Hemati, M.S., Williams, M.O. & Rowley, C.W. 2014 Dynamic mode decomposition for large and streaming datasets. Phys. Fluids 26 (11), 111701.CrossRefGoogle Scholar
Holmes, P., Lumley, J.L., Berkooz, G. & Rowley, C.W. 2012 Turbulence, Coherent Structures, Dynamical Systems and Symmetry. Cambridge University Press.CrossRefGoogle Scholar
Hsu, M.-C. & Bazilevs, Y. 2012 Fluid–structure interaction modeling of wind turbines: simulating the full machine. Comput. Mech. 50 (6), 821833.CrossRefGoogle Scholar
Hurdal, M.K., Bowers, P.L., Stephenson, K., De Witt, L.S., Rehm, K., Schaper, K. & Rottenberg, D.A. 1999 Quasi-conformally flat mapping the human cerebellum. In International Conference on Medical Image Computing and Computer-Assisted Intervention, pp. 279–286. Springer.CrossRefGoogle Scholar
Jeun, J., Nichols, J.W & Jovanović, M.R. 2016 Input-output analysis of high-speed axisymmetric isothermal jet noise. Phys. Fluids 28 (4), 047101.CrossRefGoogle Scholar
Jørgensen, B.H., Sørensen, J.N. & Brøns, M. 2003 Low-dimensional modeling of a driven cavity flow with two free parameters. Theor. Comput. Fluid Dyn. 16 (4), 299317.Google Scholar
Kamensky, D., Hsu, M.-C., Schillinger, D., Evans, J.A., Aggarwal, A., Bazilevs, Y., Sacks, M.S. & Hughes, T.J.R. 2015 An immersogeometric variational framework for fluid–structure interaction: application to bioprosthetic heart valves. Comput. Meth. Appl. Mech. Engng 284, 10051053.CrossRefGoogle ScholarPubMed
Kehoe, M.W. 1995 A historical overview of flight flutter testing. NASA Tech. Rep. 4720. NASA.Google Scholar
Kern, S. & Koumoutsakos, P. 2006 Simulations of optimized anguilliform swimming. J. Expl Biol. 209 (24), 48414857.CrossRefGoogle ScholarPubMed
Kovalsky, S.Z., Aigerman, N., Basri, R. & Lipman, Y. 2015 Large-scale bounded distortion mappings. ACM Trans. Graph. 34 (6), 191.CrossRefGoogle Scholar
Kutz, J.N. 2013 Data-Driven Modeling & Scientific Computation: Methods for Complex Systems & Big Data. Oxford University Press.Google Scholar
Kutz, J.N., Fu, X. & Brunton, S.L. 2016 Multiresolution dynamic mode decomposition. SIAM. J. Appl. Dyn. Syst. 15 (2), 713735.CrossRefGoogle Scholar
Lanata, F. & Del Grosso, A. 2006 Damage detection and localization for continuous static monitoring of structures using a proper orthogonal decomposition of signals. Smart Mater. Struct. 15 (6), 1811.CrossRefGoogle Scholar
Lang, S. 2012 Fundamentals of Differential Geometry, vol. 191. Springer Science & Business Media.Google Scholar
Lee, Y.T., Lam, K.C. & Lui, L.M. 2016 Landmark-matching transformation with large deformation via n-dimensional quasi-conformal maps. J. Sci. Comput. 67 (3), 926954.CrossRefGoogle Scholar
LeGresley, P. & Alonso, J. 2000 Airfoil design optimization using reduced order models based on proper orthogonal decomposition. In Fluids 2000 Conference and Exhibit, p. 2545. AIAA.CrossRefGoogle Scholar
Lei, C., Cheng, L. & Kavanagh, K. 2000 A finite difference solution of the shear flow over a circular cylinder. Ocean Engng 27 (3), 271290.CrossRefGoogle Scholar
Li, H. & Hartley, R. 2007 Conformal spherical representation of 3D genus-zero meshes. Pattern Recognit. 40 (10), 27422753.CrossRefGoogle Scholar
Liberge, E. & Hamdouni, A. 2010 Reduced order modelling method via proper orthogonal decomposition (POD) for flow around an oscillating cylinder. J. Fluids Struct. 26 (2), 292311.CrossRefGoogle Scholar
Lighthill, M.J. 1960 Note on the swimming of slender fish. J. Fluid Mech. 9 (2), 305317.CrossRefGoogle Scholar
Liu, H., Wassersug, R. & Kawachi, K. 1996 A computational fluid dynamics study of tadpole swimming. J. Expl Biol. 199 (6), 12451260.Google ScholarPubMed
Liu, J. & Hu, H. 2010 Biological inspiration: from carangiform fish to multi-joint robotic fish. J. Bionic Engng 7 (1), 3548.CrossRefGoogle Scholar
Lumley, J.L. 1967 The structure of inhomogeneous turbulent flows. In Atmospheric Turbulence and Radio Wave Propagation (ed. A.M. Yaglom & V.I. Tatarsky). Nauka.Google Scholar
Ly, H.V. & Tran, H.T. 2001 Modeling and control of physical processes using proper orthogonal decomposition. Math. Comput. Model. 33 (1–3), 223236.CrossRefGoogle Scholar
Maertens, A.P., Gao, A. & Triantafyllou, M.S. 2017 Optimal undulatory swimming for a single fish-like body and for a pair of interacting swimmers. J. Fluid Mech. 813, 301345.CrossRefGoogle Scholar
Marchese, A.D., Onal, C.D. & Rus, D. 2014 Autonomous soft robotic fish capable of escape maneuvers using fluidic elastomer actuators. Soft Robot. 1 (1), 7587.CrossRefGoogle ScholarPubMed
Mariappan, S., Gardner, A., Richter, K. & Raffel, M. 2013 Analysis of dynamic stall using dynamic mode decomposition technique. In 31st AIAA Applied Aerodynamics Conference, p. 3040. AIAA.CrossRefGoogle Scholar
Marsden, J.E. 1981 Lectures on Geometric Methods in Mathematical Physics. SIAM.CrossRefGoogle Scholar
Martín-Alcántara, A., Fernandez-Feria, R. & Sanmiguel-Rojas, E. 2015 Vortex flow structures and interactions for the optimum thrust efficiency of a heaving airfoil at different mean angles of attack. Phys. Fluids 27 (7), 073602.CrossRefGoogle Scholar
McKeon, B.J., Sharma, A.S. & Jacobi, I. 2013 Experimental manipulation of wall turbulence: a systems approach. Phys. Fluids 25 (3), 031301.CrossRefGoogle Scholar
Menon, K. & Mittal, R. 2020 a Dynamic mode decomposition based analysis of flow over a sinusoidally pitching airfoil. J. Fluids Struct. 94, 102886.CrossRefGoogle Scholar
Menon, K. & Mittal, R. 2020 b On the initiation and sustenance of flow-induced vibration of cylinders: insights from force partitioning. arXiv:2006.11649.CrossRefGoogle Scholar
Mezić, I. 2013 Analysis of fluid flows via spectral properties of the Koopman operator. Annu. Rev. Fluid Mech. 45, 357378.CrossRefGoogle Scholar
Michelin, S., Smith, S.G.L. & Glover, B.J. 2008 Vortex shedding model of a flapping flag. J. Fluid Mech. 617, 110.CrossRefGoogle Scholar
Mittal, R. & Iaccarino, G. 2005 Immersed boundary methods. Annu. Rev. Fluid Mech. 37, 239261.CrossRefGoogle Scholar
Moghaddam, B. & Pentland, A. 1995 Probabilistic visual learning for object detection. In Proceedings of IEEE International Conference on Computer Vision, pp. 786–793. IEEE.Google Scholar
Morgan, H.L. Jr. 2002 Experimental test results of energy efficient transport (EET) high-lift airfoil in langley low-turbulence pressure tunnel. NASA.Google Scholar
Moriche, M., Flores, O. & García-Villalba, M. 2017 On the aerodynamic forces on heaving and pitching airfoils at low Reynolds number. J. Fluid Mech. 828, 395423.CrossRefGoogle Scholar
Noack, B.R., Afanasiev, K., Morzyński, M., Tadmor, G. & Thiele, F. 2003 A hierarchy of low-dimensional models for the transient and post-transient cylinder wake. J. Fluid Mech. 497, 335363.CrossRefGoogle Scholar
Ojima, A. & Kamemoto, K. 2005 Numerical simulation of unsteady flows around a fish. In Proceedings of ICVFM, pp. 21–23.Google Scholar
Paillé, G.-P. & Poulin, P. 2012 As-conformal-as-possible discrete volumetric mapping. Comput. Graph. 36 (5), 427433.CrossRefGoogle Scholar
Pozrikidis, C. 2011 Introduction to Theoretical and Computational Fluid Dynamics. Oxford University Press.Google Scholar
Ravindran, S.S. 2000 A reduced-order approach for optimal control of fluids using proper orthogonal decomposition. Intl J. Numer. Meth. Fluids 34 (5), 425448.3.0.CO;2-W>CrossRefGoogle Scholar
Roshko, A. 1961 Experiments on the flow past a circular cylinder at very high Reynolds number. J. Fluid Mech. 10 (3), 345356.CrossRefGoogle Scholar
Roweis, S.T. 1998 EM algorithms for PCA and SPCA. In Advances in Neural Information Processing Systems, pp. 626–632. MIT Press.Google Scholar
Rowley, C.W., Colonius, T. & Murray, R.M. 2004 Model reduction for compressible flows using POD and Galerkin projection. Physica D 189 (1–2), 115129.CrossRefGoogle Scholar
Rowley, C.W., Mezić, I., Bagheri, S., Schlatter, P. & Henningson, D.S. 2009 Spectral analysis of nonlinear flows. J. Fluid Mech. 641, 115127.CrossRefGoogle Scholar
Saffman, P.G. 1992 Vortex Dynamics. Cambridge University Press.Google Scholar
Saiki, E.M. & Biringen, S. 1996 Numerical simulation of a cylinder in uniform flow: application of a virtual boundary method. J. Comput. Phys. 123 (2), 450465.CrossRefGoogle Scholar
Schmid, P.J. 2010 Dynamic mode decomposition of numerical and experimental data. J. Fluid Mech. 656, 528.CrossRefGoogle Scholar
Schmidt, O.T. & Colonius, T. 2020 Guide to spectral proper orthogonal decomposition. AIAA J. 58 (3), 10231033.CrossRefGoogle Scholar
Sfakiotakis, M., Lane, D.M. & Davies, J.B.C. 1999 Review of fish swimming modes for aquatic locomotion. IEEE J. Ocean. Engng 24 (2), 237252.CrossRefGoogle Scholar
Shoele, K. & Zhu, Q. 2015 Drafting mechanisms between a dolphin mother and calf. J. Theor. Biol. 382, 363377.CrossRefGoogle ScholarPubMed
Sieber, M., Paschereit, C.O. & Oberleithner, K. 2016 Spectral proper orthogonal decomposition. J. Fluid Mech. 792, 798828.CrossRefGoogle Scholar
Sirovich, L. 1987 Turbulence and the dynamics of coherent structures. I. Coherent structures. Q. Appl. Maths 45 (3), 561571.CrossRefGoogle Scholar
Spagnolie, S.E. & Shelley, M.J. 2009 Shape-changing bodies in fluid: hovering, ratcheting, and bursting. Phys. Fluids 21 (1), 013103.CrossRefGoogle Scholar
Steele, S.C., Weymouth, G.D. & Triantafyllou, M.S. 2017 Added mass energy recovery of octopus-inspired shape change. J. Fluid Mech. 810, 155174.CrossRefGoogle Scholar
Tadmor, G., Bissex, D., Noack, B., Morzynski, M., Colonius, T. & Taira, K. 2008 Temporal-harmonic specific POD mode extraction. In 4th Flow Control Conference, p. 4190. AIAA.CrossRefGoogle Scholar
Taira, K., Brunton, S.L., Dawson, S.T.M., Rowley, C.W., Colonius, T., McKeon, B.J., Schmidt, O.T., Gordeyev, S., Theofilis, V. & Ukeiley, L.S. 2017 Modal analysis of fluid flows: an overview. AIAA J. 55 (12), 129.CrossRefGoogle Scholar
Takizawa, K., Henicke, B., Puntel, A., Spielman, T. & Tezduyar, T.E. 2012 Space-time computational techniques for the aerodynamics of flapping wings. J. Appl. Mech. 79 (1), 010903.CrossRefGoogle Scholar
Taylor, G.I. 1953 Formation of a vortex ring by giving an impulse to a circular disk and then dissolving it away. J. Appl. Phys. 24 (1), 104104.CrossRefGoogle Scholar
Taylor, J.A. & Glauser, M.N. 2004 Towards practical flow sensing and control via POD and LSE based low-dimensional tools. Trans. ASME: J. Fluids Engng 126 (3), 337345.Google Scholar
Theofilis, V. 2011 Global linear instability. Annu. Rev. Fluid Mech. 43, 319352.CrossRefGoogle Scholar
Tipping, M.E. & Bishop, C.M. 1999 Probabilistic principal component analysis. J. R. Stat. Soc. B 61 (3), 611622.CrossRefGoogle Scholar
Towne, A., Schmidt, O.T. & Colonius, T. 2018 Spectral proper orthogonal decomposition and its relationship to dynamic mode decomposition and resolvent analysis. J. Fluid Mech. 847, 821867.CrossRefGoogle Scholar
Triantafyllou, M.S. & Triantafyllou, G.S. 1995 An efficient swimming machine. Sci. Am. 272 (3), 6470.CrossRefGoogle Scholar
Troshin, V., Seifert, A., Sidilkover, D. & Tadmor, G. 2016 Proper orthogonal decomposition of flow-field in non-stationary geometry. J. Comput. Phys. 311, 329337.CrossRefGoogle Scholar
Tu, J.H., Rowley, C.W., Luchtenburg, D.M., Brunton, S.L. & Kutz, J.N. 2014 On dynamic mode decomposition: theory and applications. J. Comput. Dyn. 1, 391.CrossRefGoogle Scholar
Tytell, E.D., Hsu, C.-Y., Williams, T.L., Cohen, A.H. & Fauci, L.J. 2010 Interactions between internal forces, body stiffness, and fluid environment in a neuromechanical model of lamprey swimming. Proc. Natl Acad. Sci. 107 (46), 1983219837.CrossRefGoogle Scholar
Ukeiley, L., Cordier, L., Manceau, R., Delville, J., Glauser, M. & Bonnet, J.P. 2001 Examination of large-scale structures in a turbulent plane mixing layer. Part 2. Dynamical systems model. J. Fluid Mech. 441, 67108.CrossRefGoogle Scholar
Vercauteren, T., Pennec, X., Perchant, A. & Ayache, N. 2007 Non-parametric diffeomorphic image registration with the demons algorithm. In International Conference on Medical Image Computing and Computer-Assisted Intervention, pp. 319–326. Springer.CrossRefGoogle Scholar
Videler, J.J. & Hess, F. 1984 Fast continuous swimming of two pelagic predators, saithe (pollachius virens) and mackerel (scomber scombrus): a kinematic analysis. J. Expl Biol. 109 (1), 209228.Google Scholar
Videler, J.J. 2012 Fish Swimming. Springer Science & Business Media.Google Scholar
Wang, Z.J. 2000 Vortex shedding and frequency selection in flapping flight. J. Fluid Mech. 410, 323341.CrossRefGoogle Scholar
Wang, Z.J., Birch, J.M. & Dickinson, M.H. 2004 Unsteady forces and flows in low Reynolds number hovering flight: two-dimensional computations vs robotic wing experiments. J. Expl Biol. 207 (3), 449460.CrossRefGoogle ScholarPubMed
Wang, T.-K. & Shoele, K. 2018 Aeroelastic flutter in the presence of an active flap. In 2018 Fluid Dynamics Conference, p. 3089. AIAA.CrossRefGoogle Scholar
Wang, Y., et al. . 2003 Volumetric harmonic map. Commun. Inf. Syst. 3 (3), 191202.Google Scholar
Wassersug, R.J. & von Sechendorf Hoff, K. 1985 The kinematics of swimming in anuran larvae. J. Expl Biol. 119 (1), 130.Google Scholar
Webb, P.W. 1971 The swimming energetics of trout: II. Oxygen consumption and swimming efficiency. J. Expl Biol. 55 (2), 521540.Google ScholarPubMed
Weymouth, G.D. & Triantafyllou, M.S. 2012 Global vorticity shedding for a shrinking cylinder. J. Fluid Mech. 702, 470487.CrossRefGoogle Scholar
Wu, T.Y.-T. 1971 Hydromechanics of swimming propulsion. Part 1. Swimming of a two-dimensional flexible plate at variable forward speeds in an inviscid fluid. J. Fluid Mech. 46 (2), 337355.CrossRefGoogle Scholar
Wu, J., Liu, L. & Liu, T. 2018 Fundamental theories of aerodynamic force in viscous and compressible complex flows. Prog. Aerosp. Sci. 99, 2763.CrossRefGoogle Scholar
Yanushauskas, A. 1970 On harmonic mappings of three dimensional domains. Siber. Math. J. 11 (4), 684696.CrossRefGoogle Scholar
Yu, J., Tan, M., Wang, S. & Chen, E. 2004 Development of a biomimetic robotic fish and its control algorithm. IEEE Trans. Syst. Man Cybern. B 34 (4), 17981810.CrossRefGoogle ScholarPubMed
Zeng, W. & Gu, X.D. 2011 Registration for 3D surfaces with large deformations using quasi-conformal curvature flow. In CVPR 2011, pp. 2457–2464. IEEE.CrossRefGoogle Scholar
Zhang, C., Hedrick, T.L. & Mittal, R. 2015 Centripetal acceleration reaction: an effective and robust mechanism for flapping flight in insects. PloS One 10 (8), e0132093.CrossRefGoogle ScholarPubMed
Zhang, H., Rowley, C.W., Deem, E.A. & Cattafesta, L.N. 2019 Online dynamic mode decomposition for time-varying systems. SIAM J. Appl. Dyn. Syst. 18 (3), 15861609.CrossRefGoogle Scholar
Zhao, M., Cheng, L., Teng, B. & Liang, D. 2005 Numerical simulation of viscous flow past two circular cylinders of different diameters. Appl. Ocean Res. 27 (1), 3955.CrossRefGoogle Scholar
Zhu, Q. & Peng, Z. 2009 Mode coupling and flow energy harvesting by a flapping foil. Phys. Fluids 21 (3), 033601.CrossRefGoogle Scholar