If you use our software for your research, we would be grateful if you could cite one or more of the following papers.

C. D. Cantwell, D. Moxey, A. Comerford, A. Bolis, G. Rocco, G. Mengaldo, D. De Grazia, S. Yakovlev, J-E. Lombard, D. Ekelschot, B. Jordi, H. Xu, Y. Mohamied, C. Eskilsson, B. Nelson, P. Vos, C. Biotto, R. M. Kirby, and S. J. Sherwin, “Nektar++: An open-source spectral/hp element framework,” Computer physics communications, vol. 192, pp. 205-219, 2015.

D. Moxey, C. D. Cantwell, Y. Bao, A. Cassinelli, G. Castiglioni, S. Chun, E. Juda, E. Kazemi, K. Lackhove, J. Marcon, G. Mengaldo, D. Serson, M. Turner, H. Xu, J. Peiró, R. M. Kirby, S. J. Sherwin, “Nektar++: enhancing the capability and application of high-fidelity spectral/hp element methods”, Computer physics communications, vol. 249, 107110, 2020

This helps demonstrate impact to funding agencies and supports further development of the code.

Below is a list of publications which describe the developments in, or application of, Nektar++.

Core Numerical Methods · Applications · PhD theses

Core numerical methods

2024

  • R. C. Moura, L. D. Fernandes, A. F. C. da Silva and S. J. Sherwin
    Joint-mode diffusion analysis of spectral/hp continuous Galerin Methods: Towards superior dissipation estimates for implicit LES
    Computer Methods in Applied Mechanics and Engineering, 2024. doi 10.1016/j.cma.2024.117025 
    @article{Moura-2024,
  title = {Joint-mode diffusion analysis of spectral/hp continuous Galerin Methods: Towards superior dissipation estimates for implicit LES},
  journal = {Computer Methods in Applied Mechanics and Engineering},
  author = {Moura, R.C. and Fernandes, L.D. and da Silva, A.F. C. and Sherwin, S. J.},
  doi = {10.1016/j.cma.2024.117025},
  groups = {core},
  year = {2024}
}
    We present a new linear eigensolution analysis technique that provides superior estimates of dissipation distribution in wavenumber space for the continuous Galerkin (CG) method. The technique builds upon traditional dispersion–diffusion analyses that have been applied to spectral/hp element methods, but in particular is an improvement upon the non-modal eigenanalysis approach proposed by Fernandez et al. (2019). The present technique takes into account the indirect effects that dispersion may have on dissipation, as recently discussed by Moura et al. (2022), in order to better represent dissipation itself. Also, a concept used by the dynamic mode decomposition (DMD) community is invoked to weight the relative contribution of the multiple diffusion curves that stem from temporal eigenanalysis. This allows for obtaining a single dissipation profile in wavenumber space, so that the proposed technique is named joint-mode analysis. Although the non-modal approach also provides a single diffusion curve, the joint-mode dissipation curve is shown to correlate significantly better with the energy spectrum of Burgers’ turbulence at large and intermediate scales, which is particularly relevant for implicit large-eddy simulation (LES). The proposed technique is readily extensible to other spectral/hp element methods.

2022

  • G. Vivarelli, J. A. Isler, F. Montomoli, S. J. Sherwin and P. Adami
    High-Order Spectral/hp Compressible and Incompressible Comparison of Transitional Boundary-Layers Subject to a Realistic Pressure Gradient and High Reynolds Number
    in Turbo Expo: Power for Land, Sea, and Air, 2022, 86113, p. V10CT32A024.
    @inproceedings{vivarelli-2022,
  title = {High-Order Spectral/$hp$ Compressible and Incompressible Comparison of Transitional Boundary-Layers Subject to a Realistic Pressure Gradient and High $Reynolds$ Number},
  author = {Vivarelli, Guglielmo and Isler, Jo{\~a}o Anderson and Montomoli, Francesco and Sherwin, Spencer J and Adami, Paolo},
  booktitle = {Turbo Expo: Power for Land, Sea, and Air},
  volume = {86113},
  pages = {V10CT32A024},
  year = {2022},
  organization = {American Society of Mechanical Engineers},
  groups = {core}
}
  • M. W. Hess, A. Lario, G. Mengaldo and G. Rozza
    Reduced order modeling for spectral element methods: current developments in Nektar++ and further perspectives
    arXiv preprint arXiv:2201.05404, 2022.
    @article{hess-2022,
  title = {Reduced order modeling for spectral element methods: current developments in {Nektar++} and further perspectives},
  author = {Hess, Martin W and Lario, Andrea and Mengaldo, Gianmarco and Rozza, Gianluigi},
  journal = {arXiv preprint arXiv:2201.05404},
  year = {2022},
  groups = {core}
}

2021

  • Z.-G. Yan, Y. Pan, G. Castiglioni, K. Hillewaert, J. Peiró, D. Moxey and S. J. Sherwin
    Nektar++: Design and implementation of an implicit, spectral/hp element, compressible flow solver using a Jacobian-free Newton Krylov approach
    Computers & Mathematics with Applications, 81, pp. 351–372, 2021.
    @article{yan-2021a,
  title = {Nektar++: Design and implementation of an implicit, spectral/hp element, compressible flow solver using a Jacobian-free Newton Krylov approach},
  author = {Yan, Zhen-Guo and Pan, Yu and Castiglioni, Giacomo and Hillewaert, Koen and Peir{\'o}, Joaquim and Moxey, David and Sherwin, Spencer J},
  journal = {Computers \& Mathematics with Applications},
  volume = {81},
  pages = {351--372},
  year = {2021},
  publisher = {Elsevier},
  groups = {core}
}

2019

  • J. Marcon, D. A. Kopriva, S. J. Sherwin and J. Peiró
    A high resolution PDE approach to quadrilateral mesh generation
    Journal of Computational Physics, 399, p. 108918, 2019.
    @article{marcon-2019,
  title = {A high resolution {PDE} approach to quadrilateral mesh generation},
  author = {Marcon, Julian and Kopriva, David A and Sherwin, Spencer J and Peir{\'o}, Joaquim},
  journal = {Journal of Computational Physics},
  volume = {399},
  pages = {108918},
  year = {2019},
  publisher = {Elsevier},
  groups = {core}
}
  • C. D. Cantwell and A. S. Nielsen
    A minimally intrusive low-memory approach to resilience for existing transient solvers
    Journal of Scientific Computing, 78, pp. 565–581, 2019.
    @article{Cantwell-2019,
  title = {A minimally intrusive low-memory approach to resilience for existing transient solvers},
  author = {Cantwell, Chris D and Nielsen, Allan S},
  journal = {Journal of Scientific Computing},
  volume = {78},
  pages = {565--581},
  year = {2019},
  publisher = {Springer},
  groups = {core}
}

2018

  • J. Cohen, J. Marcon, M. Turner, C. Cantwell, S. J. Sherwin, J. Peiró and D. Moxey
    Simplifying high-order mesh generation for computational scientists
    2018.
    @inproceedings{co.ma.tu.ca:18,
  title = {Simplifying high-order mesh generation for computational scientists},
  author = {Cohen, Jeremy and Marcon, Julian and Turner, Michael and Cantwell, Chris and Sherwin, SJ and Peir{\'o}, Joaquim and Moxey, David},
  year = {2018},
  organization = {CEUR Workshop Proceedings},
  keywords = {nekmesh},
  groups = {core}
}
  • M. Bareford, N. Johnson and M. Weiland
    Improving Nektar++ IO performance for cray XC architecture
    Cray User Group Proceedings, Stockholm, Sweden, 2018.
    @article{ba.jo.we:18,
  title = {Improving Nektar++ IO performance for cray XC architecture},
  author = {Bareford, Michael and Johnson, Nick and Weiland, Michele},
  journal = {Cray User Group Proceedings, Stockholm, Sweden},
  year = {2018},
  keywords = {nektar++},
  groups = {core}
}

2017

  • R. C. Moura, G. Mengaldo, J. Peiró and S. J. Sherwin
    On the eddy-resolving capability of high-order discontinuous Galerkin approaches to implicit LES/under-resolved DNS of Euler turbulence
    Journal of Computational Physics, 330, pp. 615–623, 2017.
    @article{moura-2017,
  title = {On the eddy-resolving capability of high-order discontinuous {Galerkin} approaches to implicit {LES}/under-resolved {DNS} of {Euler} turbulence},
  author = {Moura, R.C. and Mengaldo, G. and Peir{\'o}, J. and Sherwin, S.J.},
  journal = {Journal of Computational Physics},
  volume = {330},
  pages = {615--623},
  year = {2017},
  keywords = {nektar++},
  publisher = {Elsevier},
  groups = {core}
}
  • G. Mengaldo, R. C. Moura, B. Giralda, J. Peiró and S. J. Sherwin
    Spatial eigensolution analysis of discontinuous Galerkin schemes with practical insights for under-resolved computations and implicit LES
    Computers & Fluids, 2017.
    @article{mengaldo-2017,
  title = {Spatial eigensolution analysis of discontinuous Galerkin schemes with practical insights for under-resolved computations and implicit {LES}},
  author = {Mengaldo, G. and Moura, R.C. and Giralda, B. and Peir{\'o}, J. and Sherwin, S.J.},
  journal = {Computers \& Fluids},
  year = {2017},
  keywords = {nektar++},
  publisher = {Elsevier},
  groups = {core}
}

Applications

2023

  • D. Lindblad, S. J. Sherwin, C. Cantwell, J. Lawrence, A. Proenca and M. Moragues Ginard
    Large Eddy Simulations of Isolated and Installed Jet Noise using the High-Order Discontinuous Galerkin Method
    in AIAA SciTech 2023 Forum, 2023, p. 1546.
    @inproceedings{li.sh.ca.la:23,
  title = {Large Eddy Simulations of Isolated and Installed Jet Noise using the High-Order Discontinuous Galerkin Method},
  author = {Lindblad, Daniel and Sherwin, Spencer J and Cantwell, Chris and Lawrence, Jack and Proenca, Anderson and Moragues Ginard, Margarida},
  booktitle = {AIAA SciTech 2023 Forum},
  pages = {1546},
  year = {2023},
  groups = {app}
}
  • D. Lindblad, J. Isler, M. Moragues, S. J. Sherwin and C. D. Cantwell
    Nektar++: Development of the Compressible Flow Solver for Large Scale Aeroacoustic Applications
    2023.
    @article{lindblad-2023,
  title = {{Nektar++}: {Development} of the Compressible Flow Solver for Large Scale Aeroacoustic Applications},
  author = {Lindblad, D and Isler, J and Moragues, M and Sherwin, SJ and Cantwell, C. D.},
  year = {2023},
  groups = {app}
}
  • M. Lahooti, Y. Bao, D. Scott, R. Palacios and S. J. Sherwin
    LES/DNS fluid-structure interaction simulation of non-linear slender structures in Nektar++ framework
    Computer Physics Communications, 282, p. 108528, 2023.
    @article{lahooti-2023,
  title = {{LES/DNS} fluid-structure interaction simulation of non-linear slender structures in {Nektar++} framework},
  author = {Lahooti, Mohsen and Bao, Yan and Scott, David and Palacios, Rafael and Sherwin, Spencer J},
  journal = {Computer Physics Communications},
  volume = {282},
  pages = {108528},
  year = {2023},
  publisher = {Elsevier},
  groups = {app}
}
  • D. S. Lampropoulos, I. D. Boutopoulos, G. C. Bourantas, K. Miller, P. E. Zampakis and V. C. Loukopoulos
    Hemodynamics of anterior circulation intracranial aneurysms with daughter blebs: investigating the multidirectionality of blood flow fields
    Computer Methods in Biomechanics and Biomedical Engineering, 26 (1), pp. 113–125, 2023. doi 10.1080/10255842.2022.2048374 
    @article{lampropoulos-2023,
  author = {Lampropoulos, Dimitrios S and Boutopoulos, Ioannis D. and Bourantas, George C. and Miller, Karol and Zampakis, Petros E. and Loukopoulos, Vassilios C.},
  title = {Hemodynamics of anterior circulation intracranial aneurysms with daughter blebs: investigating the multidirectionality of blood flow fields},
  journal = {Computer Methods in Biomechanics and Biomedical Engineering},
  volume = {26},
  number = {1},
  pages = {113--125},
  year = {2023},
  publisher = {Taylor \& Francis},
  doi = {10.1080/10255842.2022.2048374},
  note = {PMID: 35297711},
  url = {https://doi.org/10.1080/10255842.2022.2048374},
  eprint = {https://doi.org/10.1080/10255842.2022.2048374},
  groups = {app}
}
    Recent advances in diagnostic neuroradiological imaging, allowed the detection of unruptured intracranial aneurysms (IAs). The shape – irregular or multilobular – of the aneurysmal dome, is considered as a possible rupture risk factor, independently of the size, the location and patient medical background. Disturbed blood flow fields in particular is thought to play a key role in IAs progression. However, there is an absence of widely-used hemodynamic indices to quantify the extent of a multi-directional disturbed flow. We simulated blood flow in twelve patient-specific anterior circulation unruptured intracranial aneurysms with daughter blebs utilizing the spectral/hp element framework Nektar++. We simulated three cardiac cycles using a volumetric flow rate waveform while we considered blood as a Newtonian fluid. To investigate the multidirectionality of the blood flow fields, besides the time-averaged wall shear stress (TAWSS), we calculated the oscillatory shear index (OSI), the relative residence time (RRT) and the time-averaged cross flow index (TACFI). Our CFD simulations suggest that in the majority of our vascular models there is a formation of complex intrasaccular flow patterns, resulting to low and highly oscillating WSS, especially in the area of the daughter blebs. The existence of disturbed multi-directional blood flow fields is also evident by the distributions of the RRT and the TACFI. These findings further support the theory that IAs with daughter blebs are linked to a potentially increased rupture risk.

2022

  • B. Liu, C. D. Cantwell, D. Moxey, G. Mashy and S. J. Sherwin
    Vectorised spectral/hp element matrix-free operator for anisotropic heat transport in tokamak edge plasma
    in 8th European Congress on Computational Methods in Applied Sciences and Engineering, 2022.
    @inproceedings{liu-2022,
  title = {Vectorised spectral/$hp$ element matrix-free operator for anisotropic heat transport in tokamak edge plasma},
  author = {Liu, Bin and Cantwell, CD and Moxey, David and Mashy, G and Sherwin, SJ},
  booktitle = {8th European Congress on Computational Methods in Applied Sciences and Engineering},
  year = {2022},
  organization = {Newcastle University},
  groups = {app}
}
  • D. Lindblad, S. Sherwin, C. Cantwell, J. Lawrence, A. Proenca and M. Moragues Ginard
    Aeroacoustic analysis of a subsonic jet using the discontinuous Galerkin method
    in 28th AIAA/CEAS Aeroacoustics 2022 Conference, 2022, p. 2932.
    @inproceedings{liindblad-2022,
  title = {Aeroacoustic analysis of a subsonic jet using the discontinuous {Galerkin} method},
  author = {Lindblad, Daniel and Sherwin, Spencer and Cantwell, Chris and Lawrence, Jack and Proenca, Anderson and Moragues Ginard, Margarida},
  booktitle = {28th AIAA/CEAS Aeroacoustics 2022 Conference},
  pages = {2932},
  year = {2022},
  groups = {app}
}
  • G. Lyu, C. Chen, X. Du, M. S. Mughal and S. J. Sherwin
    Open-source framework for transonic boundary layer natural transition analysis over complex geometries in Nektar++
    in AIAA AVIATION 2022 Forum, 2022, p. 4032.
    @inproceedings{lyu-2022,
  title = {Open-source framework for transonic boundary layer natural transition analysis over complex geometries in {Nektar++}},
  author = {Lyu, Ganlin and Chen, Chao and Du, Xi and Mughal, Mohammed S and Sherwin, Spencer J},
  booktitle = {AIAA AVIATION 2022 Forum},
  pages = {4032},
  year = {2022},
  groups = {app}
}

2021

  • H. Jiang, X. Ju and Y. Lu
    Large-Eddy Simulation of Flow Past a Circular Cylinder Using OpenFOAM and Nektar++
    in International Conference on Offshore Mechanics and Arctic Engineering, 2021, 85185, p. V008T08A019.
    @inproceedings{jiang-2021,
  title = {Large-Eddy Simulation of Flow Past a Circular Cylinder Using {OpenFOAM} and {Nektar++}},
  author = {Jiang, Hongyi and Ju, Xiaoying and Lu, Yucen},
  booktitle = {International Conference on Offshore Mechanics and Arctic Engineering},
  volume = {85185},
  pages = {V008T08A019},
  year = {2021},
  organization = {American Society of Mechanical Engineers},
  groups = {app}
}
  • M. Z. Hossain, C. D. Cantwell and S. J. Sherwin
    A spectral/hp element method for thermal convection
    International Journal for Numerical Methods in Fluids, 93 (7), pp. 2380–2395, 2021.
    @article{hossain-2021,
  title = {A spectral/$hp$ element method for thermal convection},
  author = {Hossain, Mohammad Z and Cantwell, Chris D and Sherwin, Spencer J},
  journal = {International Journal for Numerical Methods in Fluids},
  volume = {93},
  number = {7},
  pages = {2380--2395},
  year = {2021},
  publisher = {Wiley Online Library},
  groups = {app}
}
  • A. V. Proskurin and A. M. Sagalakov
    A simple scenario of the laminar breakdown in liquid metal flows
    Magnetohydrodynamics (0024-998X), 57 (2), 2021.
    @article{proskurin-2021,
  title = {A simple scenario of the laminar breakdown in liquid metal flows},
  author = {Proskurin, AV and Sagalakov, AM},
  journal = {Magnetohydrodynamics (0024-998X)},
  volume = {57},
  number = {2},
  year = {2021},
  groups = {app}
}

2020

  • Mejı́a Manuel F, D. Serson, R. C. Moura, B. S. Carmo, J. Escobar-Vargas and A. González-Mancera
    Erosion Wear Evaluation Using Nektar++
    in Spectral and High Order Methods for Partial Differential Equations ICOSAHOM 2018: Selected Papers from the ICOSAHOM Conference, London, UK, July 9-13, 2018, 2020, pp. 419–428.
    @inproceedings{mejia-2020,
  title = {Erosion Wear Evaluation Using {Nektar++}},
  author = {Mej{\'\i}a, Manuel F and Serson, Douglas and Moura, Rodrigo C and Carmo, Bruno S and Escobar-Vargas, Jorge and Gonz{\'a}lez-Mancera, Andr{\'e}s},
  booktitle = {Spectral and High Order Methods for Partial Differential Equations {ICOSAHOM 2018}: Selected Papers from the {ICOSAHOM} Conference, London, UK, July 9-13, 2018},
  pages = {419--428},
  year = {2020},
  organization = {Springer International Publishing},
  groups = {app}
}
  • G. Guo, J. Gong and M. Zhang
    Numerical investigation on flow characteristics of low-speed flow over a cavity with small aspect ratio
    International Journal of Mechanical Sciences, 178, p. 105632, 2020.
    @article{guo-2020,
  title = {Numerical investigation on flow characteristics of low-speed flow over a cavity with small aspect ratio},
  author = {Guo, Guangming and Gong, Junjie and Zhang, Mengqi},
  journal = {International Journal of Mechanical Sciences},
  volume = {178},
  pages = {105632},
  year = {2020},
  publisher = {Elsevier},
  groups = {app}
}
  • Fürst Jiřı́, M. Lasota, J. Musil and J. Pech
    Numerical Investigation of Aeroelastic Flutter in Two-Dimensional Cascade of Compressor Blades
    in MATEC Web of Conferences, 2020, 328, p. 02020.
    @inproceedings{furst-2020,
  title = {Numerical Investigation of Aeroelastic Flutter in Two-Dimensional Cascade of Compressor Blades},
  author = {F{\"u}rst, Ji{\v{r}}{\'\i} and Lasota, Martin and Musil, Josef and Pech, Jan},
  booktitle = {MATEC Web of Conferences},
  volume = {328},
  pages = {02020},
  year = {2020},
  organization = {EDP Sciences},
  groups = {app}
}
  • F. F. Buscariolo, W. Hambli, J. Slaughter and S. Sherwin
    Using a spectral/hp element method for high-order implicit-LES of bluff automotive geometries
    2020.
    @article{buscariolo-2020,
  title = {Using a spectral/$hp$ element method for high-order implicit-{LES} of bluff automotive geometries},
  author = {Buscariolo, Filipe Fabian and Hambli, Walid and Slaughter, James and Sherwin, Spencer},
  publisher = {Loughborough University},
  year = {2020},
  groups = {app}
}

2017

  • S. Ma, C.-W. Kang, T.-B. A. Lim, C.-H. Wu and O. Tutty
    Wake of two side-by-side square cylinders at low Reynolds numbers
    Physics of Fluids, 29 (3), p. 033604, 2017.
    @article{ma-2017,
  title = {Wake of two side-by-side square cylinders at low {Reynolds} numbers},
  author = {Ma, Shengwei and Kang, Chang-Wei and Lim, Teck-Bin Arthur and Wu, Chih-Hua and Tutty, Owen},
  journal = {Physics of Fluids},
  volume = {29},
  number = {3},
  pages = {033604},
  year = {2017},
  publisher = {AIP Publishing},
  keywords = {nektar++},
  groups = {app}
}
  • S. Chun and C. Eskilsson
    Method of moving frames to solve the shallow water equations on arbitrary rotating curved surfaces
    Journal of Computational Physics, 333, pp. 1–23, 2017.
    @article{chun+eskilsson-2017,
  title = {Method of moving frames to solve the shallow water equations on arbitrary rotating curved surfaces},
  author = {Chun, S and Eskilsson, Claes},
  journal = {Journal of Computational Physics},
  volume = {333},
  pages = {1--23},
  year = {2017},
  keywords = {moving frames},
  publisher = {Elsevier},
  groups = {app}
}
  • S. Chun
    Method of moving frames to solve time-dependent Maxwell’s equations on anisotropic curved surfaces: Applications to invisible cloak and ELF propagation
    Journal of Computational Physics, 340, pp. 85–104, 2017.
    @article{chun-2017,
  title = {Method of moving frames to solve time-dependent {Maxwell}'s equations on anisotropic curved surfaces: {Applications} to invisible cloak and {ELF} propagation},
  author = {Chun, Sehun},
  journal = {Journal of Computational Physics},
  volume = {340},
  pages = {85--104},
  year = {2017},
  keywords = {moving frames},
  publisher = {Elsevier},
  groups = {app}
}

PhD theses

2022

  • A. J. Jurecki
    Characterization of flow states in corrugated annuli
    PhD thesis, Instytut Techniki Lotniczej i Mechaniki Stosowanej, 2022.
    @phdthesis{jurecki-2022,
  title = {Characterization of flow states in corrugated annuli},
  author = {Jurecki, Aleksander Jan},
  year = {2022},
  school = {Instytut Techniki Lotniczej i Mechaniki Stosowanej},
  groups = {thesis}
}

2021

  • M. Duran
    The Stability of Two-Dimensional Cylinder Wakes in the Presence of a Wavy Ground
    PhD thesis, University of Central Florida, 2021.
    @phdthesis{duran-2021,
  title = {The Stability of Two-Dimensional Cylinder Wakes in the Presence of a Wavy Ground},
  author = {Duran, Matt},
  year = {2021},
  school = {University of Central Florida},
  groups = {thesis}
}
  • Z. Yan
    Efficient implicit spectral/hp element DG techniques for compressible flows
    PhD thesis, Imperial College London, 2021.
    @phdthesis{yan-2021b,
  title = {Efficient implicit spectral/$hp$ element {DG} techniques for compressible flows},
  author = {Yan, Zhenguo},
  year = {2021},
  school = {Imperial College London},
  groups = {thesis}
}
  • A. Cassinelli
    A spectral/hp element DNS study of flow past low-pressure turbine cascades and the effects of inflow conditions
    PhD thesis, Imperial College London, 2021.
    @phdthesis{cassinelli-2021,
  title = {A spectral/$hp$ element {DNS} study of flow past low-pressure turbine cascades and the effects of inflow conditions},
  author = {Cassinelli, Andrea},
  year = {2021},
  school = {Imperial College London},
  groups = {thesis}
}
  • V. Saini
    Performance and accuracy of high-order accurate large-eddy simulations for gas turbine combustor aerodynamics
    PhD thesis, Loughborough University, 2021.
    @phdthesis{saini-2021,
  title = {Performance and accuracy of high-order accurate large-eddy simulations for gas turbine combustor aerodynamics},
  author = {Saini, Vishal},
  year = {2021},
  school = {Loughborough University},
  groups = {thesis}
}

2020

  • E. Cooke
    Modelling the effect of step and roughness features on swept wing boundary layer instabilities
    PhD thesis, Imperial College London, 2020.
    @phdthesis{cook-2020,
  title = {Modelling the effect of step and roughness features on swept wing boundary layer instabilities},
  author = {Cooke, Emma},
  year = {2020},
  school = {Imperial College London},
  groups = {thesis}
}

2019

  • F. Fabian Buscariolo
    Spectral/hp large eddy simulation of vortex-dominated automotive flows around bluff bodies with diffuser and complex front wing geometries
    PhD thesis, Imperial College London, 2019.
    @phdthesis{buscariolo-2019,
  title = {Spectral/hp large eddy simulation of vortex-dominated automotive flows around bluff bodies with diffuser and complex front wing geometries},
  author = {Fabian Buscariolo, Filipe},
  year = {2019},
  school = {Imperial College London},
  groups = {thesis}
}
    In this research project, it is demonstrated the use of spectral/hp element method for simulations of fully 3D complex geometries. Such solutions at high Reynolds numbers and with higher order polynomials were previously intractable due to numerical stability issues affecting the convergence of the scheme. For this approach, we have employed the latest development of continuous Galerkin spectral vanishing viscosity (CG-SVV) with a discontinuous Galerkin (DG) mimicking kernel. Together with dealiasing techniques, the numerical stability and convergence characteristics of the spectral/hp element method have been greatly improved. These advances in numerical methods are also supported by novel meshing strategies, taking advantage of the additional flexibility in changing the uniform polynomial orders of the mesh and the solution. As a result, efficient simulations can be formulated with consistent and highly accurate solutions obtainable. Specific for this work, the focus is on complex geometries often found in automotive engineering. To reduce the computational demands, this research explored the use of symmetry boundary conditions for large eddy simulations (LES) using a half model. It is found that if only the average flow properties near the body are of interest, such an approach can provide more than 50% reduction in simulation time while maintaining the solution quality. In terms of improving the solution resolution, as one might expect from a p-type method we have observed that increasing the polynomial order can be a more effective approach in comparison to conventional mesh refinement. In the three test cases, we have successfully exploited the use of polynomial accuracy of 4th, 5th and 6th order. This is the first comprehensive study using polynomials of such high orders, and the corresponding solutions are obtained for fully 3D geometries using spectral/hp element method. Three test cases have been considered, the first being the simulations of the original Ahmed Body serves as a validation study for 3D simulations of the spectral/hp element method. The Ahmed Body is one of the most widely studied bluff bodies used for automotive conceptual studies and computational fluid dynamics (CFD) software validation. For this validation study, the differences in results obtained using various polynomial orders for the mesh as well as for the solution interpolation have been examined in detail. With the proposed approach, we were able to obtain fairly good correlations with the aerodynamic quantities for polynomial orders of 5 and above. Regarding the flow features around the body, solutions from the 6th order polynomial showed clear advantage in the slant vortex intensity. With the computational facilities, further increase of solution polynomial order is not feasible; however, the required solution resolution can also be obtained via the use of local mesh refinement. We determine that this level of solution accuracy, after comparing with various studies in the literature, cannot be obtainable using steady-state simulations such as the very popular Reynolds averaged Navier-Stokes (RANS) method. Based on the validation result, the second test case involved the simulations of Ahmed Body geometries with a simplified diffuser using the proposed method. This case serves as an independent study examining the suitability of the method for design analysis. Using the same 6th order polynomial and Refined mesh, the solution successfully identified the flow features consistent with to past literature on underbody diffusers. Additionally, we have found that the geometry of the reference body imposes a quite significant influence on the performance of the diffuser, as well as identified some strong interplay between the lower-side vortex and the diffuser flow. The toolchain has clearly demonstrated its capability in assisting integrated design analysis for a simplified road vehicle equipped with a diffuser. In the final test case, a new benchmark study case for aerodynamic design of high-performance vehicles and racing cars, the Imperial front wing is proposed. This study consists of a multi-element front-wing based on a Formula One front wing design. It generates complex flow features including ground effects, and multiple vortex system development and interaction. We used this test case as a challenging examination of our proposed method and simulation strategy using the spectral/hp element method. The simulations were also supported by an independent experimental study and results obtained for comparison achieved a high level of agreement. Using a polynomial order of 4th and above have successfully correlated the flow velocity fields at various planes downstream, while increasing the polynomial order to 5th will further result in a good matching of flow visualisation details. From all three test cases, the spectral/hp element method when applied to suitable meshes at reasonably polynomial orders has been able to accurately and consistently yield reliable solutions in good agreement with experiment. The benefits of using high order polynomials for mesh generation of complex geometries, and for solution interpolation of higher accuracy have enabled the use of much coarser meshes than would typically be applied in commercial CFD codes. The progress made in this research is a solid step forward for the adaptation of the spectral/hp element for industrial level applications.
  • N. Yadav
    Hydrodynamic instability and mixing enhancement in grooved channels
    PhD thesis, The Institute of Aeronautics and Applied Mechanics, 2019.
    @phdthesis{yadav-2019,
  title = {Hydrodynamic instability and mixing enhancement in grooved channels},
  author = {Yadav, Nikesh},
  year = {2019},
  school = {The Institute of Aeronautics and Applied Mechanics},
  groups = {thesis}
}