Analyzing the Interaction of Vortex and Gas–Liquid Interface Dynamics in Fuel Spray Nozzles by Means of Lagrangian-Coherent Structures (2D)

Dauch, Thilo F.; Ates, Cihan; Rapp, Tobias; Keller, Marc C.; Chaussonnet, Geoffroy; Kaden, J.; Okraschevski, Max; Koch, Rainer; Dachsbacher, Carsten; Bauer, Hans‐Jörg

doi:10.3390/en12132552

Cited by 11 publications

(9 citation statements)

References 26 publications

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“…2016; Dauch et al. 2019) flows. To elaborate on the relation between the FTLE and LMA, we consider a double-gyre flow pattern of interest in geophysical flows.…”

Section: Resultsmentioning

confidence: 99%

Lagrangian approach for modal analysis of fluid flows

Shinde

Gaitonde

2021

J. Fluid Mech.

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Common modal decomposition techniques for flow-field analysis, data-driven modelling and flow control, such as proper orthogonal decomposition and dynamic mode decomposition, are usually performed in an Eulerian (fixed) frame of reference with snapshots from measurements or evolution equations. The Eulerian description poses some difficulties, however, when the domain or the mesh deforms with time as, for example, in fluid–structure interactions. For such cases, we first formulate a Lagrangian modal analysis (LMA) ansatz by a posteriori transforming the Eulerian flow fields into Lagrangian flow maps through an orientation and measure-preserving domain diffeomorphism. The development is then verified for Lagrangian variants of proper orthogonal decomposition and dynamic mode decomposition using direct numerical simulations of two canonical flow configurations at Mach 0.5, i.e. the lid-driven cavity and flow past a cylinder, representing internal and external flows, respectively, at pre- and post-bifurcation Reynolds numbers. The LMA is demonstrated for several situations encompassing unsteady flow without and with boundary and mesh deformation as well as non-uniform base flows that are steady in Eulerian but not in Lagrangian frames. We show that application of LMA to steady non-uniform base flow yields insights into flow stability and post-bifurcation dynamics. LMA naturally leads to Lagrangian coherent flow structures and connections with finite-time Lyapunov exponents. We examine the mathematical link between finite-time Lyapunov exponents and LMA by considering a double-gyre flow pattern. Dynamically important flow features in the Lagrangian sense are recovered by performing LMA with forward and backward (adjoint) time procedures.

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“…2016; Dauch et al. 2019) flows. To elaborate on the relation between the FTLE and LMA, we consider a double-gyre flow pattern of interest in geophysical flows.…”

Section: Resultsmentioning

confidence: 99%

Lagrangian approach for modal analysis of fluid flows

Shinde

Gaitonde

2021

J. Fluid Mech.

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“…It should be noted that the suitability of this modeling strategy has already been demonstrated for the primary breakup of liquids in realistic spray nozzle configurations at both atmospheric and high pressure conditions. [12,13,14,15].…”

Section: Smoothed Particles Hydrodynamics (Sph)mentioning

confidence: 99%

“…The time difference |t − t 0 | is the reference time span (∆t) and needs to be adjusted individually according to the time scale of the underlying flow phenomenon [13]. If t > t 0 the FTLE is called "forward in time" FTLE + and for t < t 0 "backward in time" FTLE − respectively.…”

Section: Lcs and Ftlementioning

confidence: 99%

“…In this study, FTLE − are utilized to track the coherent structures around the FB nozzles with a ∆t of 100 µs. In order to efficiently compute FTLE fields based on SPH data sets, the interactive data exploration environment "postAtom" mainly developed and implemented by the Institut für Visualisierung und Datenanalyse (IVD) in joint cooperation with ITS [13] was employed.…”

Section: Lcs and Ftlementioning

confidence: 99%

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Analysis of the Backflow Recirculation in Flow Blurring Nozzles via Lagrangian Coherent Structures

Ates

Giovannoni

Bürkle

et al. 2021

ICLASS

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The liquid atomization process relies on the disturbance of the liquid surface by various forces. In the case of "flow-blurring" (FB) atomization, this is achieved by inducing turbulence near the liquid channel exit. In this study, we analyze the underlying dynamics of these coherent turbulent structures and their role in the primary atomization within the FB regime. For that purpose, Smoothed Particles Hydrodynamics (SPH) simulations have been conducted using the geometry of an FB atomizer, which was also studied experimentally. An in-house developed visualization and data exploration platform (postAtom) was used to capture the time-resolved, Lagrangian coherent structures (LCSs) via the finite-time Lyapunov exponent (FTLE) fields. The results indicate that the design of the mixing chamber can trigger an oscillatory behavior at the nozzle exit, which has a direct impact on the evolution of the micro-ligaments and the consecutive primary atomization. It is further shown how the FTLE fields can be used as a guide to optimize the nozzle geometry.

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“…All of the mentioned approaches are still being actively researched [18,19,[24][25][26][27][28][29][30][31], and the academic and engineering community is constantly re-evaluating which approach gives the best trade-off between the cost and accuracy for each problem. This work presents the development of a Eulerian multi-fluid framework for predicting dynamic spray behavior in OpenFOAM.…”

Section: Introductionmentioning

confidence: 99%

Development of a Eulerian Multi-Fluid Solver for Dense Spray Applications in OpenFOAM

et al. 2020

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The new generation of internal combustion engines is facing various research challenges which often include modern fuels and different operating modes. A robust modeling framework is essential for predicting the dynamic behavior of such complex phenomena. In this article, the implementation, verification, and validation of a Eulerian multi-fluid model for spray applications within the OpenFOAM toolbox are presented. Due to its open-source nature and broad-spectrum of available libraries and solvers, OpenFOAM is an ideal platform for academic research. The proposed work utilizes advanced interfacial momentum transfer models to capture the behavior of deforming droplets at a high phase fraction. Furthermore, the WAVE breakup model is employed for the transfer of mass from larger to smaller droplet classes. The work gives detailed instructions regarding the numerical implementation, with a dedicated section dealing with the implementation of the breakup model within the Eulerian multi-fluid formulation. During the verification analysis, the model proved to give stable and consistent results in terms of the selected number of droplet classes and the selected spatial and temporal resolution. In the validation section, the capability of the developed model to predict the dynamic behavior of non-evaporating sprays is presented. It was confirmed that the developed framework could be used as a stable foundation for future fuel spray modeling.

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Analyzing the Interaction of Vortex and Gas–Liquid Interface Dynamics in Fuel Spray Nozzles by Means of Lagrangian-Coherent Structures (2D)

Cited by 11 publications

References 26 publications

Lagrangian approach for modal analysis of fluid flows

Lagrangian approach for modal analysis of fluid flows

Analysis of the Backflow Recirculation in Flow Blurring Nozzles via Lagrangian Coherent Structures

Development of a Eulerian Multi-Fluid Solver for Dense Spray Applications in OpenFOAM

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