Convective instabilities in a laminar shock-wave/boundary-layer interaction
Niessen S.E.M., Groot, K.J., Hickel, S., Terrapon, V.E. (2023)Niessen S.E.M., Groot, K.J., Hickel, S., Terrapon, V.E. (2023)
Physics of Fluids 35: 024101. doi: 10.1063/5.0135590
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 problem formulated in a moving frame of reference.
GPU-accelerated simulations for eVTOL aerodynamic analysis
Pasquariello, V., Bunk, Y., Eberhardt, S., Huang, P.-H., Matheis, J., Ugolotti, M., Hickel, S. (2023)
AIAA Scitech paper 2023-2107. doi: 10.2514/6.2023-2107
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 targets more quickly. This paper presents a cutting-edge large-eddy simulations (LES) solver developed to enable over-night turnaround times for full aircraft simulations on advanced graphics processing unit (GPU) architectures.
Experimental and numerical investigation into the drag performance of dimpled surfaces in a turbulent boundary layer
van Campenhout, O.W.G., van Nesselrooij, M., Lin, Y.Y., van Oudheusden, B.W., Hickel, S. (2023)
International Journal of Heat and Fluid Flow 100: 109110. doi: 10.1016/j.ijheatfluidflow.2023.109110
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 has a dimple diameter of 20 mm and a depth of 0.5 mm.
An enhanced algorithm for online Proper Orthogonal Decomposition and its parallelization for unsteady simulations
Li, X., Hulshoff, S., Hickel, S. (2022)
Computers & Mathematics with Applications 126: 43-59. doi: 10.1016/j.camwa.2022.09.007
We present an enhanced online algorithm based on incremental Singular Value Decomposition (SVD), which can be used to efficiently perform a Proper Orthogonal Decomposition (POD) analysis on the fly. The proposed enhanced algorithm for modal analysis has significantly better computational efficiency than the standard incremental SVD and good parallel scalability, such that the strong reduction of computational cost is maintained in parallel computations.
Unsteady mechanisms in shock wave and boundary layer interactions over a forward-facing step
Hu, W., Hickel, S., van Oudheusden, B.W. (2022)
Journal of Fluid Mechanics 949: A2. doi: 10.1017/jfm.2022.737
The flow over a forward-facing step (FFS) at Ma∞=1.7 and Re𝛿 = 13 718 is investigated by well-resolved large-eddy simulation. To investigate effects of upstream flow structures and turbulence on the low-frequency dynamics of the shock wave/boundary layer interaction (SWBLI), two cases are considered: one with a laminar inflow and one with a turbulent inflow.
Large eddy simulations of reacting and non-reacting transcritical fuel sprays using multiphase thermodynamics
Fathi, M., Hickel, S., Roekaerts, D. (2022)
Physics of Fluids 34: 085131. doi: 10.1063/5.0099154
We present a novel framework for high-fidelity simulations of inert and reacting sprays with highly accurate and computationally efficient models for complex real-gas effects in high-pressure environments, especially for the hybrid subcritical/supercritical mode of evaporation during the mixing of fuel and oxidizer at transcritical conditions.
Direct numerical simulation of interaction between a stationary crossflow instability and forward-facing steps
Casacuberta, J., Hickel, S., Westerbeek, S., Kotsonis, M. (2022)
Journal of Fluid Mechanics 943: A46. doi: 10.1017/jfm.2022.456
The interaction between forward-facing steps of several heights and a pre-existing critical stationary crossflow instability of a swept-wing boundary layer is analysed.
Verification and Validation of Immersed Boundary Solvers for Hypersonic Flows with Gas-Surface Interaction
Baskaya, A.O., Capriati, M., Ninni, D., Bonelli, F., Pascazio, G., Turchi, A., Magin T., Hickel, S. (2022)
AIAA Aviation Forum, Chicago. AIAA paper 2022-3276. doi: 10.2514/6.2022-3276
Verification and validation results of two immersed boundary solvers, INCA and CHESS, for atmospheric entry flows characterized by complex fluid thermochemistry and gas-surface interactions (GSI) are presented. Results are compared with those obtained with the body-conforming solver US3D, which is coupled to the same external thermochemistry library, Mutation++, as INCA and CHESS. In these campaigns, the INCA solver has shown an almost perfect agreement with the body-conforming reference solver and other reference results from literature.
Secondary instabilities in swept-wing boundary layers: Direct Numerical Simulations and BiGlobal stability analysis
Casacuberta, J., Groot, K.J., Hickel, S., Kotsonis, M. (2022)
SciTech Forum and Exposition, San Diego. AIAA paper 2022-2330, doi: 10.2514/6.2022-2330
The evolution of secondary instabilities in a three-dimensional stationary-crossflow-dominated 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.
Experimental investigation of shock–shock interactions with variable inflow Mach number
Laguarda, L., Santiago Patterson, J., Schrijer, F.F.J., van Oudheusden, B.W., Hickel, S. (2021)
Shock Waves 3: 457-468. doi: 10.1007/s00193-021-01029-3
Experiments on shock–shock interactions were conducted in a transonic–supersonic wind tunnel with variable free-stream Mach number functionality. Transition between the regular interaction (RI) and the Mach interaction (MI) was induced by variation of the free-steam Mach number for a fixed interaction geometry, as opposed to most previous studies where the shock generator angles are varied at constant Mach number.
Adaptive reduced-order modeling for non-linear fluid-structure interaction
Thari, A., Pasquariello, V., Aage, N., Hickel, S. (2021)
Computers and Fluids 229: 105099. doi: 10.1016/j.compfluid.2021.105099
We present an adaptive reduced-order model for the efficient time-resolved simulation of fluid–structure interaction problems with complex and non-linear deformations. The model is based on repeated linearizations of the structural balance equations. Upon each linearization step, the number of unknowns is strongly decreased by using modal reduction, which leads to a substantial gain in computational efficiency.
Towards adjoint-based mesh refinement for Large Eddy Simulation using reduced-order primal solutions: Preliminary 1D Burgers study
Li, X., Hulshoff, S., Hickel, S. (2021)
Computer Methods in Applied Mechanics and Engineering 379: 113733. doi: 10.1016/j.cma.2021.113733
Adaptive Mesh Refinement (AMR) is potentially an effective way to automatically generate computational meshes for high-fidelity simulations such as Large Eddy Simulation (LES). When combined with adjoint methods, which are able to localize error contributions, AMR can generate meshes that are optimal for computing a physical quantity of interest (e.g. lift or drag).
Customized data-driven RANS closures for bi-fidelity LES–RANS optimization
Zhang, Y., Dwight, R.P., Schmelzer, M., Gómez, J.F., Han, Z.-H., Hickel, S. (2021)
Journal of Computational Physics 432: 110153. doi: 10.1016/j.jcp.2021.110153
Multi-fidelity optimization methods promise a high-fidelity optimum at a cost only slightly greater than a low-fidelity optimization. This promise is seldom achieved in practice, due to the requirement that low- and high-fidelity models correlate well. In this article, we propose an efficient bi-fidelity shape optimization method for turbulent fluid-flow applications with Large-Eddy Simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) as the high- and low-fidelity models within a hierarchical-Kriging surrogate modelling framework.
Mechanisms of interaction between stationary crossflow instabilities and forward-facing steps
Casacuberta, J., Hickel, S., Kotsonis, M. (2021)
AIAA Scitech paper 2021-0854. doi: 10.2514/6.2021-0854
We study the interaction between a stationary crossflow instability and forward-facing steps in a swept-wing boundary layer using Direct Numerical Simulations (DNS). The station- ary primary crossflow mode is imposed at the inflow. Steps of several heights are modeled.
Low-frequency unsteadiness mechanisms in shock wave/turbulent boundary layer interactions over a backward-facing step
Hu, W., Hickel, S., van Oudheusden, B.W. (2021)
Journal of Fluid Mechanics 915: A107. doi: 10.1017/jfm.2021.95
The low-frequency unsteady motions behind a backward-facing step (BFS) in a turbulent flow at Ma=1.7 and Re∞=1.3718×107 m−1 are investigated using a well-resolved large-eddy simulation.
Rapid multi-component phase-split calculations using volume functions and reduction methods
Fathi, M., Hickel, S. (2021)
AIChE Journal 67: e17174. doi: 10.1002/aic.17174
We present a new family of fast and robust methods for the calculation of the vapor–liquid equilibrium at isobaric-isothermal (PT-flash), isochoric-isothermal (VT-flash), isenthalpic-isobaric (HP-flash), and isoenergetic-isochoric (UV-flash) conditions. The framework is provided by formulating phase-equilibrium conditions for multi-component mixtures in an effectively reduced space based on the molar specific value of the recently introduced volume function derived from the Helmholtz free energy.