Introducing an extension of a recently derived dimension-reduced model for an infinitely deep inviscid and irrotational layer, a two-layer system is examined in the present paper. A second thin viscous layer is added on top of the original one-layer system. The set-up is a combination of a long-wave approximation (upper layer) and a deep-water approximation (lower layer). Linear stability analysis shows the emergency of Rayleigh-Taylor and Kelvin-Helmholtz instabilities. Finally, numerical solutions of the model reveal spatial and temporal pattern formation in the weakly nonlinear regime of both instabilities. This article is part of the theme issue 'Stokes at 200 (Part 1)'.
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http://dx.doi.org/10.1098/rsta.2019.0508 | DOI Listing |
Phys Rev E
August 2024
GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, 64291 Darmstadt, Germany.
A model for the single mode, two-dimensional Rayleigh-Taylor instability in ideal, incompressible, immiscible, and inviscid fluids is developed as an extension of a previous linear model based on the Newton's second law [A. R. Piriz et al.
View Article and Find Full Text PDFACS Omega
August 2024
Lab of Mechanical Structure & Biomechanics, Anhui Agricultural University, Hefei 230036, China.
As the core of a hypersonic propulsion system, the effective mixing efficiency of fuel and air in a supersonic combustor is crucial for its performance. This study focuses on a cold supersonic flow and employs computational fluid dynamics (CFD) techniques combined with Euler-Lagrange method's discrete-phase model (DPM) for multiphase flows, K-H and R-T (Kelvin-Helmholtz and Rayleigh-Taylor) mixing and atomization models, turbulence models, and surface evaporation models to investigate the injection, atomization, and mixing characteristics of kerosene in supersonic airflow. In order to enhance the mixing efficiency between kerosene and air while reducing flow losses, this study examines a staggered dual-jet injection scheme, with the dual jets arranged at the center of the cavity and having a dual-jet spacing of 10 and 20 mm, respectively.
View Article and Find Full Text PDFUltrason Sonochem
August 2024
Faculty of Mechanical Engineering, University of Ljubljana, Askerceva 6, 1000 Ljubljana, Slovenia. Electronic address:
The paper investigates the oil-water emulsification process inside a micro-venturi channel. More specifically, the possible influence of Kelvin-Helmholtz instability on the emulsification process. High-speed visualizations were conducted inside a square venturi constriction with throat dimensions of 450 µm by 450 µm, both under visible light and X-Rays.
View Article and Find Full Text PDFPhys Rev E
November 2023
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Two Reynolds-averaged Navier-Stokes models with full Reynolds-stress transport (RST) and tensor eddy viscosity are presented. These new models represent RST extensions of the k-2L-a-C and k-ϕ-L-a-C models by Morgan [Phys. Rev.
View Article and Find Full Text PDFEntropy (Basel)
May 2022
Research Unit of Mechanical Modeling, Energy and Materials, National School of Engineers of Gabes, University of Gabes, UR17ES47, Gabes 6029, Tunisia.
Even though there is a pressing interest in clean energy sources, compression ignition (CI) engines, also called diesel engines, will remain of great importance for transportation sectors as well as for power generation in stationary applications in the foreseeable future. In order to promote applications dealing with complex diesel alternative fuels by facilitating their integration in numerical simulation, this paper targets three objectives. First, generate novel diesel fuel surrogates with more than one component.
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