Persona:
Hernández Rodríguez, Julio

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0000-0003-0633-0556
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Hernández Rodríguez
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Julio
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2021 - 20254
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Autor: Esteban Paz, Adolfo ×

Resultados de la búsqueda

Mostrando 1 - 4 de 4
  • Miniatura
    Publicación
    A numerical model for the simulation of complex planar Newtonian interfaces
    (Elsevier, 2025-01) Esteban Paz, Adolfo; Hernández Rodríguez, Julio; Tajuelo Rodríguez, Javier; Rubio González, Miguel Ángel
    We present a numerical model for the simulation of complex planar interfaces at which moving solid objects can be immersed, reproducing a wide variety of experimental conditions. The mathematical model consists of the Navier-Stokes equations governing the incompressible viscous flow in the liquid subphase, the transport equation for the evolution of the surfactant concentration at the interface, and the interfacial stress balance equation. The equations are simplified by treating the problem as isothermal and the surfactant as insoluble. The bulk flow equations are discretized using a collocated finite volume method, while the interfacial flow equations are discretized using a finite area method. The Boussinesq-Scriven interface constitutive model and a variant form accounting for extensional viscosity are used to describe the extra surface stress tensor. The coupling between surfactant concentration, interfacial velocity, and bulk velocity is treated implicitly by solving the interfacial and bulk equations sequentially at each time step until a stopping criterion is satisfied. The motion of the solid is treated by an arbitrary Lagrangian- Eulerian method. The model has been implemented in the OpenFOAM framework and allows the incorporation of new interface models and solvers, making the developed new package a versatile and powerful tool in the field of computational rheology. Applications of the model include the numerical simulation of flow around objects, such as probes, immersed at a complex interface, reproducing given experimental conditions, and its use as a tool in the analysis and design of interfacial stress rheometers. Several test cases have been performed to validate the model by comparing the results obtained with analytical solutions and with numerical and experimental results available in the literature.
  • Miniatura
    Publicación
    A comparative study of two open-source state-of-the-art geometric VOF methods
    (Elsevier, 2023-01-15) Esteban Paz, Adolfo; Gómez del Pino, Pablo Joaquín; López, Joaquín; Zanzi, Claudio; Roenby, Johan; Hernández Rodríguez, Julio
    We present a systematic study of geometric volume of fluid (VOF) methods provided in the gVOF and TwoPhaseFlow packages, which include algorithms that are among the most accurate proposed in recent years. In addition to contributing to their further validation, the main purpose is to evaluate, in terms of accuracy and efficiency, the relative advantages of the advection and reconstruction algorithms used in the two packages (mainly, FMFPA-CLCIR and isoAdvector-plicRDF, respectively), and to investigate the suitability of combining them. Since TwoPhaseFlow is available in OpenFOAM, gVOF was also coupled with this open source CFD toolbox to maintain the same conditions in common solvers when obtaining and comparing their results, including discretization schemes, tolerances and meshes. For the same reason, identical computational resources were also maintained. The use of a common software and hardware framework that guarantees strictly the same simulation conditions overcomes many of the limitations and uncertainties of comparisons made in previous studies. Several reconstruction and advection tests are presented, showing the differences between the algorithms in terms of accuracy, as measured by several error norms, and in terms of efficiency, as measured by CPU times consumed. Simulations of the rise of a bubble and the impact of a drop on a pool were also performed, in which the VOF methods were coupled to the same solver of the Navier–Stokes equations, and the results obtained with the two combinations of algorithms FMFPA-CLCIR and isoAdvector-plicRDF are compared with each other and, in the case of the second test, with our own experimental results. The relative advantages and limitations of the analyzed algorithms are discussed, and it is suggested that a combination of isoAdvector for advection and CLCIR for reconstruction can provide a good compromise between accuracy and efficiency.
  • Miniatura
    Publicación
    A new isosurface extraction method on arbitrary grids
    (Elsevier, 2021-11) López, Joaquín; Esteban Paz, Adolfo; Hernández Rodríguez, Julio; Gómez del Pino, Pablo Joaquín; Zamora, Rosendo; Zanzi, Claudio; Faura, Félix
    The development of interface-capturing methods (such as level-set, phase-field or volume of fluid (VOF) methods) for arbitrary 3D grids has further highlighted the need for more accurate and efficient interface reconstruction procedures. In this work, we propose a new method for the extraction of isosurfaces on arbitrary polyhedra that can be used with advantage for this purpose. The isosurface is extracted from volume fractions by a general polygon tracing procedure, which is valid for convex or non-convex geometries, even with non-planar faces. The proposed method, which can be considered as an extension of the marching cubes technique, produces consistent results even for ambiguous situations in polyhedra of arbitrary shape. To show the reproducibility of the results presented in this work, we provide the open source library isoap, which has been developed to implement the proposed method and includes test programs to demonstrate the successful extraction of isosurfaces on several grids with polyhedral cells of different types. We present results obtained not only for isosurface extraction from discrete volume fractions resulting from a volume of fluid method, but also from data sets obtained from implicit mathematical functions and signed distances to scanned surfaces. The improvement provided by the proposed method for the extraction of isosurfaces in arbitrary grids will also be very useful in other fields, such as CFD visualization or medical imaging.
  • Miniatura
    Publicación
    A contact line force model for the simulation of drop impacts on solid surfaces using volume of fluid methods
    (Elsevier, 2023-09-15) Esteban Paz, Adolfo; Gómez del Pino, Pablo Joaquín; Zanzi, Claudio; López, Joaquín; Bussmann, Markus; Hernández Rodríguez, Julio
    Characterizing the contact line dynamics on solid walls is often a crucial problem encountered in the simulation of complex interfacial unsteady flows, such as drop impacts on solid surfaces. In this work, a new model is proposed to reproduce the contact line dynamics in a simple but effective way, based on introducing in the momentum equation a force term proportional to the deviation of the calculated contact angle from the value predicted by a dynamic model that takes into account wettability hysteresis. The model has been implemented in a volume of fluid (VOF) method and is applied to the simulation of drop impacts leading to deposition outcomes, although it could be extended to other interface tracking methods and is also applicable to more complex drop impacts involving fingering and splashing. Numerous tests have been performed to evaluate the accuracy and robustness of the proposed model over a wide range of Reynolds and Weber numbers. The results substantially improve those obtained by imposing only the contact angle as a boundary condition at the contact line, and satisfactorily predict a variety of experimental results from the literature for very different impact and wettability conditions.