Searched for: author%3A%22Groot%2C+K.J.%22
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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
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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
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Groot, K.J. (author), Schuttelaars, H.M. (author)
The initial stage of the laminar–turbulent transition of semi-infinite flows can be characterized as either an absolute or convective instability, naturally associated with localized wave packets. A convective instability is directly linked to an absolute instability in a different reference frame. Therefore, our aim is to determine the...
journal article 2020
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Groot, K.J. (author), Casacuberta Puig, J. (author), Ye, Q. (author), Hickel, S. (author)
Micro-ramps are deployed to prevent boundary layer separation by creating a momentum excess close to the wall. Through Direct Numerical Simulations (DNS) of the base, instantaneous and mean flow, we identify that the perturbation dynamics in the wake of the microramp play an essential role in creating the near-wall momentum excess. To identify...
journal article 2019
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Casacuberta Puig, J. (author), Groot, K.J. (author), Ye, Q. (author), Hickel, S. (author)
Micro-ramps are popular passive flow control devices which can delay flow separation by re-energising the lower portion of the boundary layer. We compute the laminar base flow, the instantaneous transitional flow, and the mean flow around a micro-ramp immersed in a quasi-incompressible boundary layer at supercritical roughness Reynolds number...
journal article 2019
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Casacuberta Puig, J. (author), Groot, K.J. (author), Tol, H.J. (author), Hickel, S. (author)
Selective Frequency Damping (SFD) is a popular method for the computation of globally unstable steady-state solutions in fluid dynamics. The approach has two model parameters whose selection is generally unclear. In this article, a detailed analysis of the influence of these parameters is presented, answering several open questions with...
journal article 2018
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Groot, K.J. (author)
Laminar-turbulent transition dictates an increase in skin friction. The resulting turbulent skin friction contributes to approximately 40% of the total drag of commercial aircraft. Reducing the turbulent flow region by postponing transition can therefore significantly reduce the carbon footprint and costs of flying. Transition prediction is...
doctoral thesis 2018
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Groot, K.J. (author), Serpieri, J. (author), Pinna, Fabio (author), Kotsonis, M. (author)
A combined experimental and numerical approach to the analysis of the secondary stability of realistic swept-wing boundary layers is presented. Global linear stability theory is applied to experimentally measured base flows. These base flows are three-dimensional laminar boundary layers subject to spanwise distortion due to the presence of...
journal article 2018
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Casacuberta Puig, J. (author), Groot, K.J. (author), Ye, Q. (author), Hickel, S. (author)
We computed the base, instantaneous and mean flow around a micro-ramp immersed in an incompressible boundary layer. Results of our Direct<br/>Numerical Simulations (DNS) are compared with an independent stability analysis and experiments. We analyse flow structures and mechanisms that contribute to the micro-ramp functionality and find that...
conference paper 2018
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Groot, K.J. (author), Miró Miró, Fernando (author), Beyak, Ethan S. (author), Moyes, Alexander J. (author), Pinna, Fabio (author), Reed, Helen L. (author)
As the community investigates more complex flows with stronger streamwise variations and uses more physically inclusive stability techniques, such as BiGlobal theory, there is a perceived need for more accuracy in the base flows. To this end, the implication is that using these more advanced techniques, we are now including previously...
conference paper 2018
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Groot, K.J. (author), Serpieri, J. (author), Kotsonis, M. (author), Pinna, Fabio (author)
conference paper 2017
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Groot, K.J. (author), Pinna, F. (author), Van Oudheusden, B.W. (author)
The modal streamwise BiGlobal stability approach introduces problems regarding the specification of in- and outflow boundary conditions (BCs). Several conditions linked to lower hierarchical stability frameworks are elaborated and are applied to a freestream and boundary layer flow. The former case is used to demonstrate the odd-even decoupling...
journal article 2015
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Groot, K.J. (author)
Laminar to turbulent transition has an important role in the aerospace domain in view of its impact on aerodynamic drag and, regarding the high velocity regime, heat transfer. State of the art computational methods, like DNS, LES and RANS are found to be too expensive or rely on case dependent turbulence models to be used for obtaining...
master thesis 2013
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