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Chen, L. (author), Maher, G.D. (author), Hulshoff, S.J. (author)Parameters for SGS models within the variational multiscale method for the Stokes equations are determined using two different methods. Both linear and nonlinear models are considered. Firstly, optimal parameters are found using a goal-oriented model-constrained technique minimising L2 error. Secondly, parameters are obtained using the...conference paper 2014
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Correale, G. (author), Popov, I.B. (author), Ratikin, A.E. (author), Starikovskii, A.Y. (author), Hulshoff, S.J. (author), Veldhuis, L.L.M. (author)An experimental study of flow separation control with a nanosecond pulse plasma actuator was performed in wind-tunnel experiments. The discharge used had a pulse width of 12 ns and rising time of 3 ns with voltage up to 12 kV. Repetition frequency was adjustable up to 10 kHz. The first series of experiments was to measure integral effects of the...conference paper 2011
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De Borst, R. (author), Hulshoff, S.J. (author), Lenz, S. (author), Munts, E.A. (author), Van Brummelen, E.H. (author), Wall, W.A. (author)The basic idea of multiscale methods, namely the decomposition of a problem into a coarse scale and a fine scale, has in an intuitive manner been used in engineering for many decades, if not for centuries. Also in computational science, large-scale problems have been solved, and local data, for instance displacements, forces or velocities, have...conference paper 2006
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De Borst, R. (author), Hulshoff, S.J. (author), Lenz, S. (author), Munts, E.A. (author), Van Brummelen, E.H. (author), Wall, W.A. (author)The basic idea of multiscale methods, namely the decomposition of a problem into a coarse scale and a fine scale, has in an intuitive manner been used in engineering for many decades, if not for centuries. Also in computational science, large-scale problems have been solved, and local data, for instance displacements, forces or velocities, have...conference paper 2006
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Maher, G.D. (author), Hulshoff, S.J. (author)The Variational Germano Identity [1, 2] is used to optimize the coefficients of residual-based subgrid-scale models that arise from the application of a Variational Multiscale Method [3, 4]. It is demonstrated that numerical iterative methods can be used to solve the Germano relations to obtain values for the parameters of subgrid-scale models...conference paper 2014
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Cheng, L. (author), Mattei, S. (author), Fick, P.W. (author), Hulshoff, S.J. (author)A semi-continuous formulation is introduced for finding bases which minimise the error in a specific output functional of a reduced-order model. The formulation is advantageous in that it can be easily applied to nonlinear problems and functionals. A general description of the approach is given, then explicit formulations are derived for the...conference paper 2014
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Hirschberg, L. (author), Bake, F. (author), Hulshoff, S.J. (author)The downstream acoustic response due to the interaction of main-flow oriented vorticity with a choked nozzle in a swirl-free flow was experimentally demonstrated. The response was obtained by means of impulsive radial air injection in the pipe upstream from the nozzle. The resulting downstream acoustic data are shown to obey a scaling rule that...conference paper 2022
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Hirschberg, L. (author), Bake, F. (author), Knobloch, Karsten (author), Hulshoff, S.J. (author)View Video Presentation: https://doi-org.tudelft.idm.oclc.org/10.2514/6.2021-2286.vid<br/><br/>Quantitative measurements of sound due to swirl-nozzle interaction are presented for the first time. In the experiment a swirl structure was generated by means of tangential injection into a steady swirl-free flow upstream from a choked convergent...conference paper 2021
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- Jindal, Aman (author), Sinnige, T. (author), Hulshoff, S.J. (author), Veldhuis, L.L.M. (author) conference paper 2017
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Hirschberg, L. (author), Hulshoff, S.J. (author), Bake, F. (author)Indirect noise due to the interaction of flow inhomogeneities with a choked nozzle is as an important cause of combustion instability in solid rocket motors and is believed to be important in aircraft engines. A previously published experiment demonstrated that interaction of the nozzle with time-dependent axial swirl can also be a source of...conference paper 2020
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Hunter, T.P. (author), Hulshoff, S.J. (author)Numerical simulations and optimisation methods, such as mesh adaptation, rely on the accurate and inexpensive use of error estimation methods. Adjoint-based error estimation is the most accurate method, and generally the most costly. A strong contributor to this cost is the need to compute a higher resolution adjoint solution. Here, it is...contribution to periodical 2023
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Akkerman, I. (author), Bazilevs, Y. (author), Calo, V.M. (author), Hughes, T.J.R. (author), Hulshoff, S. (author)This paper examines the role of continuity of the basis in the computation of turbulent flows. We compare standard finite elements and non-uniform rational B-splines (NURBS) discretizations that are employed in Isogeometric Analysis (Hughes et al. in Comput Methods Appl Mech Eng, 194:4135–4195, 2005). We make use of quadratic discretizations...journal article 2007
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Janssens, M. (author), Hulshoff, S.J. (author)Data-driven parameterizations offer considerable potential for improving the fidelity of General Circulation Models. However, ensuring that these remain consistent with the governing equations while still producing stable simulations remains a challenge. In this paper, we propose a combined Variational-Multiscale (VMS) Artificial Neural...journal article 2022
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Li, X. (author), Hulshoff, S.J. (author), Hickel, S. (author)Adaptive mesh refinement (AMR) is potentially an effective way to automatically generate computational meshes for high-fidelity simulations such as Large Eddy Simulation (LES). Adjoint methods, which are able to localize error contributions, can be used to optimize the mesh for computing a physical quantity of interest (e.g. lift, drag)...journal article 2021
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Hirschberg, L. (author), Bake, Friedrich (author), Knobloch, Karsten (author), Rudolphi, Angelo (author), Kruck, Sebastian (author), Klose, Oliver (author), Hulshoff, S.J. (author)Measurements of sound due to swirl–nozzle interaction are presented. In the experiment a swirl structure was generated by means of unsteady tangential injection into a steady swirl-free flow upstream from a choked convergent–divergent nozzle. Ingestion of swirl by the choked nozzle caused a mass-flow rate change, which resulted in a...journal article 2021
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Chen, Linfeng (author), Hulshoff, S.J. (author), Dong, Yuhong (author)The underlying physical mechanism of the residual-based large eddy simulation (LES) based on the variational multiscale (VMS) method is clarified. Resolved large-scale energy transportation equation is mathematically derived for turbulent kinetic energy budget analysis. Firstly, statistical results of benchmark turbulent channel flow at Re...journal article 2022
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Hirschberg, L. (author), Bake, F. (author), Knobloch, K. (author), Hulshoff, S.J. (author), Hirschberg, A. (author)An experimental cold-gas study of the response of a choked convergent–divergent nozzle to swirl perturbations is presented. The perturbations were obtained by means of upstream unsteady tangential injections into initially steady flows with different values of steady background swirl. The swirl perturbations induced changes in the axial mass...journal article 2022
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Li, X. (author), Hulshoff, S.J. (author), Hickel, S. (author)Proper Orthogonal Decomposition (POD) plays an important role in the analysis of complex nonlinear systems governed by partial differential equations (PDEs), since it can describe the full-order system in a simplified but representative way using a handful of dominant dynamic modes. However, determining a POD from the results of complex...journal article 2022
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Barner, N.M. (author), Ghafourpour, L.D. (author), Güverte, M.S. (author), Modesti, D. (author), Hulshoff, S.J. (author)This work presents a transpacific airliner designed for minimal climate impact, incorporating several novel design features. These include open rotor engines, sustainable aviation fuels, natural laminar flow airfoils, and riblets. The design’s configuration and mission have been optimised simultaneously using a combination of standard...journal article 2022
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Shrestha, S. (author), Dekker, J. (author), Gerritsma, M.I. (author), Hulshoff, S.J. (author), Akkerman, I. (author)In this paper, we build on the work of Hughes and Sangalli (2007) dealing with the explicit computation of the Fine-Scale Greens’ function. The original approach chooses a set of functionals associated with a projector to compute the Fine-Scale Greens’ function. The construction of these functionals, however, does not generalise to arbitrary...journal article 2024
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