- document
-
Başkaya, A.O. (author), Hickel, S. (author), Dungan, Sean (author), Brehm, Christoph (author)Direct numerical simulations (DNS) are performed over 15° compression ramp undergoing ablation at Mach 8 to examine fluid-ablation interactions (FAI) on transitional high-speed boundary layers. The experiments at these conditions with a rigid wall are first numerically replicated for a laminar flow. Heating streaks are introduced by perturbing...conference paper 2024
- document
-
Laguarda, L. (author), Hickel, S. (author)We propose several enhancements to improve the accuracy and performance of the digital filter turbulent inflow generation technique and assess their efficacy in the context of wall-resolved large-eddy simulations of a compressible turbulent boundary layer. Improvements of accuracy include a more realistic correlation function for the...journal article 2024
- document
-
Laguarda, L. (author), Hickel, S. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)Wall-resolved large-eddy simulations (LES) are performed to investigate Reynolds number effects in supersonic turbulent boundary layers (TBLs) at Mach 2.0. The resulting database covers more than a decade of friction Reynolds number Re<sub>τ</sub>, from 242 to 5554, which considerably extends the parameter range of current high-fidelity...journal article 2024
- document
-
Başkaya, A.O. (author), Capriati, Michele (author), Turchi, Alessandro (author), Magin, Thierry (author), Hickel, S. (author)The efficacy of immersed boundary (IB) methods with adaptive mesh refinement (AMR) techniques is assessed in the context of atmospheric entry applications, including effects of chemical nonequilibrium (CNE) and gas–surface interactions (GSI). We scrutinize a conservative cut-cell IB method and two non-conservative IB methods, comparing their...journal article 2024
- document
-
Laguarda, L. (author), Hickel, S. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)The dynamic coupling between a Mach 2.0 shock-wave/turbulent boundary-layer interaction (STBLI) and a flexible panel is investigated. Wall-resolved large-eddy simulations are performed for a baseline interaction over a flat-rigid wall, a coupled interaction with a flexible panel, and a third interaction over a rigid surface that is shaped...journal article 2024
- document
-
Casacuberta Puig, J. (author), Hickel, S. (author), Kotsonis, M. (author)Achieving and maintaining laminar flow on large swept lifting surfaces of subsonic aircraft poses a considerable challenge.book chapter 2024
- document
-
Casacuberta Puig, J. (author), Hickel, S. (author), Kotsonis, M. (author)A novel mechanism is identified, through which a spanwise-invariant surface feature (a two-dimensional forward-facing step) significantly stabilizes the stationary crossflow instability of a three-dimensional boundary layer. The mechanism is termed here as reverse lift-up effect, inasmuch as it acts reversely to the classic lift-up effect;...journal article 2024
- document
-
Pasquariello, Vito (author), Bunk, Y.L. (author), Eberhardt, S. (author), Huang, Pei-Hsuan (author), Matheis, Jan (author), Ugolotti, Matteo (author), Hickel, S. (author)The demand for fast, high-fidelity, scale-resolving computational fluid dynamics (CFD) simulations is continuously growing. Especially new emerging aviation technologies, such as electrical vertical take-off and landing aircraft (eVTOL), strongly rely on advanced numerical methods to retain development life-cycle costs and achieving design...conference paper 2023
- document
-
Başkaya, A.O. (author), Hickel, S. (author)A conservative cut-cell immersed boundary (IB) method including gas-surface interactions (GSI) for the simulation of atmospheric entry flows under thermochemical nonequilibrium (TCNE) conditions is presented. The performance<br/>of the method is demonstrated for three test cases: a compression ramp, a cylinder, and a plasma wind tunnel ablator...conference paper 2023
- document
-
Shahzad, H. (author), Hickel, S. (author), Modesti, D. (author)The nacelle of aircraft engines is coated with acoustic liners to reduce engine noise. An undesirable effect of these liners is that they increase aerodynamic drag. We study this drag penalty by performing Direct Numerical Simulations of a turbulent boundary layer over an acoustic liner array at friction Reynolds number, Re τ ≈ 850–2500. We use...conference paper 2023
- document
-
Laguarda, L. (author), Hickel, S. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)Wall-resolved large-eddy simulations (LES) are carried out to investigate the aeroelastic coupling between a Mach 2.0 impinging shock-wave/turbulent boundary-layer interaction (STBLI) and a flexible thin-panel. After the initial transient, the panel exhibits self-sustained oscillatory behavior with varying oscillation amplitude, confirming the...conference paper 2023
- document
-
Shahzad, H. (author), Hickel, S. (author), Modesti, D. (author)We present pore-resolved compressible direct numerical simulations of turbulent flows grazing over perforated plates, that closely resemble the acoustic liners found on aircraft engines. Our direct numerical simulations explore a large parameter space including the effects of porosity, thickness and viscous-scaled diameter of the perforated...journal article 2023
- document
-
van Campenhout, O.W.G. (author), van Nesselrooij, M. (author), Lin, Y. (author), Casacuberta Puig, J. (author), van Oudheusden, B.W. (author), Hickel, S. (author)Although several previous studies have reported a potential drag-reducing effect of dimpled surfaces in turbulent boundary layers, there is a lack of replicability across experiments performed by different research groups. To contribute to the dialogue, we scrutinize one of the most studied dimple geometries reported in the literature, which...journal article 2023
- document
-
Niessen, S.E.M. (author), Groot, K.J. (author), Hickel, S. (author), Terrapon, Vincent E. (author)Linear stability analyses are performed to study the dynamics of linear convective instability mechanisms in a laminar shock-wave/boundary-layer interaction at Mach 1.7. In order to account for all two-dimensional gradients elliptically, we introduce perturbations into an initial-value problem that are found as solutions to an eigenvalue...journal article 2023
- document
-
Fathi, Mohamad (author), Hickel, S. (author), Roekaerts, D.J.E.M. (author)Transcritical fuel sprays form an indispensable part of high-pressure energy-conversion systems. Modeling the complex real-fluid effects in the high-pressure multiphase regime of such sprays accurately, especially the hybrid subcritical-to-supercritical mode of evaporation during mixing fuel and oxidizer, is essential and challenging. This...book chapter 2023
- document
-
Casacuberta Puig, J. (author), Groot, K.J. (author), Hickel, S. (author), Kotsonis, M. (author)The evolution of secondary instabilities in a three-dimensional stationary-crossflow-domina- ted boundary layer is investigated by means of Direct Numerical Simulations (DNS) and linear spanwise BiGlobal stability analysis. Single-frequency unsteady disturbances and a critical stationary crossflow mode are considered. Unsteady perturbation...conference paper 2022
- document
-
Başkaya, A.O. (author), Capriati, Michele Capriati (author), Ninni, Davide (author), Bonelli, Francesco (author), Pascazio, Giuseppe (author), Turchi, Alessandro (author), Magin, Thierry (author), Hickel, S. (author)During atmospheric entry, the flow environment around capsules or space debris is characterized by complex fluid thermochemistry and gas-surface interactions (GSI). Computational fluid dynamics (CFD) simulations of these conditions are crucial in the design process of such objects. A promising approach for the simulation of complex geometries is...conference paper 2022
- document
-
Shahzad, H. (author), Hickel, S. (author), Modesti, D. (author)We perform direct numerical simulations of turbulent flow at friction Reynolds number Re<sub>τ</sub>≈ 500 - 2000 grazing over perforates plates with moderate viscous-scaled orifice diameter d<sup>+</sup>≈ 40 - 160 and analyse the relation between permeability and added drag. Unlike previous studies of turbulent flows over permeable surfaces,...journal article 2022
- document
-
Doijode, P.S. (author), Hickel, S. (author), van Terwisga, T.J.C. (author), Visser, K. (author)We propose and analyse an optimization method that uses a machine learning approach to solve multi-objective, constrained propeller optimization problems. The method uses an online learning strategy where explainable supervised classifiers learn the location of the Pareto front and advise search strategies. The classifiers are trained with...journal article 2022
- document
-
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