Publications

2023
6.
 Valle N;  Verstappen R W C P
Conservation of energy in the DNS of interface-resolved multiphase fows Journal Article 
In: Exp. Comput. Multiph. Flow, vol. 4, pp. 1–15, 2023.
BibTeX
@article{Valle2023,

title = {Conservation of energy in the DNS of interface-resolved multiphase fows},

author = {N. Valle and R. W. C. P. Verstappen},

year  = {2023},

date = {2023-01-01},

journal = {Exp. Comput. Multiph. Flow},

volume = {4},

pages = {1--15},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

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2022
5.
 Valle N
Diluted-dispersed mass transfer within an AWE Journal Article 
In: 2022.
Abstract | Links | BibTeX
@article{Valle2022d,

title = {Diluted-dispersed mass transfer within an AWE},

author = {N. Valle},

url = {http://arxiv.org/abs/2209.02813},

year  = {2022},

date = {2022-01-01},

abstract = {The goal of this document is describe the multiphase transfer processes describing the bubble dynamics of a water electrolyzer. The motivation is to describe the dilute-dispersed mass transfer within and Alkaline Water Electrolyzer. Special emphasis is put on the mathematical formulation. The presentation starts by posing the governing equations and their dimensionless counterpart. By filtering the equations, the two-fluid model is presented along with the need to sub-scale and wall models. To the later aim, boundary layer equations are introduced. By reviewing self-similiarity transformations, the analysis of Blasius, Ostrach and Sparrow is reviewed for Prandtl's boundary layer equations; along with that of Leveque.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close
The goal of this document is describe the multiphase transfer processes describing the bubble dynamics of a water electrolyzer. The motivation is to describe the dilute-dispersed mass transfer within and Alkaline Water Electrolyzer. Special emphasis is put on the mathematical formulation. The presentation starts by posing the governing equations and their dimensionless counterpart. By filtering the equations, the two-fluid model is presented along with the need to sub-scale and wall models. To the later aim, boundary layer equations are introduced. By reviewing self-similiarity transformations, the analysis of Blasius, Ostrach and Sparrow is reviewed for Prandtl's boundary layer equations; along with that of Leveque.
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http://arxiv.org/abs/2209.02813
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4.
 Valle N;  Álvarez-Farré X;  Gorobets A;  Castro J;  Oliva A;  Trias F X
On the implementation of flux limiters in algebraic frameworks Journal Article 
In: Comput. Phys. Commun., vol. 271, pp. 108230, 2022, ISSN: 00104655.
Abstract | Links | BibTeX
@article{Valle2022a,

title = {On the implementation of flux limiters in algebraic frameworks},

author = {Nicolás Valle and Xavier Álvarez-Farré and Andrey Gorobets and Jesús Castro and Assensi Oliva and F. Xavier Trias},

url = {https://doi.org/10.1016/j.cpc.2021.108230 http://arxiv.org/abs/2110.03044 https://linkinghub.elsevier.com/retrieve/pii/S0010465521003428},

doi = {10.1016/j.cpc.2021.108230},

issn = {00104655},

year  = {2022},

date = {2022-01-01},

journal = {Comput. Phys. Commun.},

volume = {271},

pages = {108230},

publisher = {Elsevier B.V.},

abstract = {The use of flux limiters is widespread within the scientific computing community to capture shock discontinuities and are of paramount importance for the temporal integration of high-speed aerodynamics, multiphase flows, and hyperbolic equations in general. Meanwhile, the breakthrough of new computing architectures and the hybridization of supercomputer systems pose a huge portability challenge, particularly for legacy codes, since the computing subroutines that form the algorithms, the so-called kernels, must be adapted to various complex parallel programming paradigms. From this perspective, the development of innovative implementations relying on a minimalist set of kernels simplifies the deployment of scientific computing software on state-of-the-art supercomputers, while it requires the reformulation of algorithms, such as the aforementioned flux limiters. Equipped with basic algebraic topology and graph theory underlying the classical mesh concept, a new flux limiter formulation is presented based on the adoption of algebraic data structures and kernels. As a result, traditional flux limiters are cast into a stream of only two types of computing kernels: sparse matrix-vector multiplication and generalized pointwise binary operators. The newly proposed formulation eases the deployment of such a numerical technique in massively parallel, potentially hybrid, computing systems and is demonstrated for a canonical advection problem.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close
The use of flux limiters is widespread within the scientific computing community to capture shock discontinuities and are of paramount importance for the temporal integration of high-speed aerodynamics, multiphase flows, and hyperbolic equations in general. Meanwhile, the breakthrough of new computing architectures and the hybridization of supercomputer systems pose a huge portability challenge, particularly for legacy codes, since the computing subroutines that form the algorithms, the so-called kernels, must be adapted to various complex parallel programming paradigms. From this perspective, the development of innovative implementations relying on a minimalist set of kernels simplifies the deployment of scientific computing software on state-of-the-art supercomputers, while it requires the reformulation of algorithms, such as the aforementioned flux limiters. Equipped with basic algebraic topology and graph theory underlying the classical mesh concept, a new flux limiter formulation is presented based on the adoption of algebraic data structures and kernels. As a result, traditional flux limiters are cast into a stream of only two types of computing kernels: sparse matrix-vector multiplication and generalized pointwise binary operators. The newly proposed formulation eases the deployment of such a numerical technique in massively parallel, potentially hybrid, computing systems and is demonstrated for a canonical advection problem.
Close
https://doi.org/10.1016/j.cpc.2021.108230 http://arxiv.org/abs/2110.03044 https:[...]
doi:10.1016/j.cpc.2021.108230
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2021
3.
 Valle N;  Trias F;  Castro J
Energy Preserving Multiphase Flows: Application to Falling Films Journal Article 
In: pp. 1–11, 2021.
Links | BibTeX
@article{Valle2021b,

title = {Energy Preserving Multiphase Flows: Application to Falling Films},

author = {N. Valle and F. Trias and J. Castro},

doi = {10.23967/wccm-eccomas.2020.133},

year  = {2021},

date = {2021-01-01},

booktitle = {13th Int. ERCOFTAC Symp. Eng. Turbul. Model. Meas.},

pages = {1--11},

address = {Rhodes, Greece},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

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doi:10.23967/wccm-eccomas.2020.133
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2020
2.
 Valle N;  Trias F X;  Castro J
An energy-preserving level set method for multiphase flows Journal Article 
In: J. Comput. Phys., vol. 400, pp. 108991, 2020, ISSN: 10902716.
Abstract | Links | BibTeX
@article{Valle2020,

title = {An energy-preserving level set method for multiphase flows},

author = {N. Valle and F. X. Trias and J. Castro},

url = {https://doi.org/10.1016/j.jcp.2019.108991 https://linkinghub.elsevier.com/retrieve/pii/S0021999119306965},

doi = {10.1016/j.jcp.2019.108991},

issn = {10902716},

year  = {2020},

date = {2020-01-01},

journal = {J. Comput. Phys.},

volume = {400},

pages = {108991},

publisher = {Elsevier Inc.},

abstract = {The computation of multiphase flows presents a subtle energetic equilibrium between potential (i.e., surface) and kinetic energies. The use of traditional interface-capturing schemes provides no control over such a dynamic balance. In the spirit of the well-known symmetry-preserving and mimetic schemes, whose physics-compatible discretizations rely upon preserving the underlying mathematical structures of the space, we identify the corresponding structure and propose a new discretization strategy for curvature. The new scheme ensures conservation of mechanical energy (i.e., surface plus kinetic) up to temporal integration. Inviscid numerical simulations are performed to show the robustness of such a method.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close
The computation of multiphase flows presents a subtle energetic equilibrium between potential (i.e., surface) and kinetic energies. The use of traditional interface-capturing schemes provides no control over such a dynamic balance. In the spirit of the well-known symmetry-preserving and mimetic schemes, whose physics-compatible discretizations rely upon preserving the underlying mathematical structures of the space, we identify the corresponding structure and propose a new discretization strategy for curvature. The new scheme ensures conservation of mechanical energy (i.e., surface plus kinetic) up to temporal integration. Inviscid numerical simulations are performed to show the robustness of such a method.
Close
https://doi.org/10.1016/j.jcp.2019.108991 https://linkinghub.elsevier.com/retrie[...]
doi:10.1016/j.jcp.2019.108991
Close
2016
1.
 Valle N;  Brouwer J
Mass-Action Kinetics Approach to Concurrent H2 and CO Electrochemistry in a Patterned SOFC Anode Journal Article 
In: J. Electrochem. Soc., vol. 163, no. 13, pp. F1399–F1411, 2016, ISSN: 0013-4651.
Abstract | Links | BibTeX
@article{Valle2016,

title = {Mass-Action Kinetics Approach to Concurrent H2 and CO Electrochemistry in a Patterned SOFC Anode},

author = {Nicolás Valle and Jack Brouwer},

doi = {10.1149/2.0861613jes},

issn = {0013-4651},

year  = {2016},

date = {2016-01-01},

journal = {J. Electrochem. Soc.},

volume = {163},

number = {13},

pages = {F1399--F1411},

abstract = {SOFC is a fuel flexible technology suitable for producing clean energy. Understanding of the multi-reaction mechanism that a complex H-2-CO fuel presents to the electrochemical kinetics is numerically approached in this work. By using existing fundamental reaction mechanisms and kinetic parameters, elementary reactions involved in an SOFC anode have been assembled, modeled and analyzed. This involves both homogeneous and heterogeneous chemistry, electrochemistry and surface diffusion. The use of the patterned anode approach removes the mass transport complications and allows comparison with pre-existing experimental data. The model provides both polarization curves and surface coverage distribution, among other results, providing a high level of detail and understanding of the physical phenomena involved. In particular, analysis is focused upon understanding how the competitive H-2 and CO reactions behave. The presence of CO was found to stabilize OCV response to temperature and while it occupied most of the active sites it did not penalize overall performance except when significant product species were present. (C) 2016 The Electrochemical Society. All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close
SOFC is a fuel flexible technology suitable for producing clean energy. Understanding of the multi-reaction mechanism that a complex H-2-CO fuel presents to the electrochemical kinetics is numerically approached in this work. By using existing fundamental reaction mechanisms and kinetic parameters, elementary reactions involved in an SOFC anode have been assembled, modeled and analyzed. This involves both homogeneous and heterogeneous chemistry, electrochemistry and surface diffusion. The use of the patterned anode approach removes the mass transport complications and allows comparison with pre-existing experimental data. The model provides both polarization curves and surface coverage distribution, among other results, providing a high level of detail and understanding of the physical phenomena involved. In particular, analysis is focused upon understanding how the competitive H-2 and CO reactions behave. The presence of CO was found to stabilize OCV response to temperature and while it occupied most of the active sites it did not penalize overall performance except when significant product species were present. (C) 2016 The Electrochemical Society. All rights reserved.
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doi:10.1149/2.0861613jes
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