11 research outputs found
Staggered grids for multidimensional multiscale modelling
No full textAvailable online 10 January 2024For high accuracy and to improve simulated wave characteristics, this article extends the concept of staggered grids to novel multidimensional multiscale modelling enabling efficient computation on sparse patches. Computational schemes for wave-like systems with small dissipation are often inaccurate and unstable due to truncation errors and numerical roundoff errors. Hence simulations of wave-like systems lacking proper handling of these numerical issues often fail to represent the physical characteristics of wave phenomena. This challenge gets even more intricate for multiscale modelling, especially in multiple dimensions. But numerical schemes on staggered grids are significantly less dispersive, better model the group velocity, and preserve much of the wave characteristics. This article develops and exhaustively studies all 167 040 possible 2D multiscale staggered grids. Our catalog (Divahar, 2023) interactively plots all of them. Only 120 multiscale staggered patch grids give stable and accurate multiscale schemes. Specifically, this article develops these 120 multiscale staggered grids and demonstrates their stability, accuracy, and wave-preserving characteristic for equation-free multiscale modelling of weakly damped linear waves. These characteristics of the developed multiscale staggered grids must also hold in general for multiscale modelling of many complex spatio-temporal physical phenomena such as the general computational fluid dynamics.J. Divahar, A.J. Roberts, Trent W. Mattner, J.E. Bunder, Ioannis G. Kevrekidi
Large‐scale simulation of shallow water waves via computation only on small staggered patches
No full textA multiscale computational scheme is developed to use given small microscale simulations of complicated physical wave processes to empower macroscale system‐level predictions. By coupling small patches of simulations over unsimulated space, large savings in computational time are realizable. Here, we generalize the patch scheme to the case of wave systems on staggered grids in two‐dimensional (2D) space. Classic macroscale interpolation provides a generic coupling between patches that achieves consistency between the emergent macroscale simulation and the underlying microscale dynamics. Spectral analysis indicates that the resultant scheme empowers feasible computation of large macroscale simulations of wave systems even with complicated underlying physics. As an example of the scheme's application, we use it to simulate some simple scenarios of a given turbulent shallow water model.Judith E. Bunder, Jayaraman Divahar, Ioannis G. Kevrekidis, Trent W. Mattner, Anthony J. Robert
Two novel families of multiscale staggered patch schemes efficiently simulate large-scale, weakly damped, linear waves
No full textLink to a related website: https://unpaywall.org/10.1016/j.cma.2023.116133, Open Access via UnpaywallMany multiscale wave systems exhibit macroscale emergent behaviour, for example, the fluid dynamics of floods and tsunamis. Resolving a large range of spatial scales typically requires prohibitively high computational costs. The small dissipation in wave systems poses a significant challenge to further developing multiscale modelling methods in multiple dimensions. This article develops and evaluates two families of equation-free multiscale methods on novel 2D staggered patch schemes, and demonstrates the power and utility of these multiscale schemes for weakly damped linear waves. A detailed study of sensitivity to numerical roundoff errors establishes the robustness of developed staggered patch schemes. Comprehensive eigenvalue analysis over a wide range of parameters establishes the stability, accuracy, and consistency of the multiscale schemes. Analysis of the computational complexity shows that the measured compute times of the multiscale schemes may be 100,000 times smaller than the compute time for the corresponding (same resolution) full-domain computation. This work provides the essential foundation for efficient large-scale simulation of challenging nonlinear multiscale waves.J. Divahar, A.J. Roberts, Trent W. Mattner, J.E. Bunder, Ioannis G. Kevrekidi
Lemon peel activated carbon: A sustainable solution for lead ion removal from E-waste bioleachate
No full textIn the investigation of sustainable materials, this study explores the viability of employing Lemon Activated Carbon (LAC) for the bio-adsorption of lead ions from e-waste bio-leachate. The novelty of this work lies in the comprehensive analyses of LAC characteristics, including particle size, surface area, zeta potential, and surface morphology. The morphology and adsorption capacity were measured using scanning electron microscope (SEM) and atomic absorption spectroscopy (AAS), confirming the efficacy of LAC in removing lead ions from the bio-leachate solutions. The surface area analysis unveiled that LAC, with a surface area of 603.7 m²/g achieved through thermal activation, exhibited competitive lead ion adsorption capacity despite its lower surface area compared to commercial-activated carbon (990 m²/g). Additionally, both LAC and CAC displayed pseudo-second-order kinetics for adsorption, with the Langmuir isotherm model fitting well (R2 = 0.9879) for LAC. The amorphous nature of LAC confirmed by X-ray diffraction (XRD) analysis and FTIR spectroscopy revealed functional surface groups, highlighting their suitability for lead ion adsorption. LAC comprised 75.82% carbon and exhibited maximum lead ion adsorption at pH 6. The optimized operating parameters achieved 89.16% lead ion removal from bio-leachate. These findings highlight the innovative utilization of lemon peel-derived activated carbon as a sustainable and environmentally friendly solution for mitigating the impacts of e-waste bio-leachate, thus contributing to the advancement of environmental remediation techniques
Accurate and efficient multiscale simulation of a heterogeneous elastic beam via computation on small sparse patches
No full textModern `smart' materials have complex microscale structure, often with unknown macroscale closure. The Equation-Free Patch Scheme empowers us to non-intrusively, efficiently, and accurately simulate over large scales through computations on only small well-separated patches of the microscale system. Here the microscale system is a solid beam of random heterogeneous elasticity. The continuing challenge is to compute the given physics on just the microscale patches, and couple the patches across un-simulated macroscale space, in order to establish efficiency, accuracy, consistency, and stability on the macroscale. Dynamical systems theory supports the scheme. This research program is to develop a systematic non-intrusive approach, both computationally and analytically proven, to model and compute accurately macroscale system levels of general complex physical and engineering systems.
References
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J. E. Bunder, I. G. Kevrekidis, and A. J. Roberts. Equation-free patch scheme for efficient computational homogenisation via self-adjoint coupling. Numer. Math. 149.2 (2021), pp. 229–272. doi: 10.1007/s00211-021-01232-5
J. E. Bunder, A. J. Roberts, and I. G. Kevrekidis. Good coupling for the multiscale patch scheme on systems with microscale heterogeneity. J. Comput. Phys. 337 (2017), pp. 154–174. doi: 10.1016/j.jcp.2017.02.004 References C175
M. Cao and A. J. Roberts. Multiscale modelling couples patches of nonlinear wave-like simulations. IMA J. Appl. Math. 81.2 (2016), pp. 228–254. doi: 10.1093/imamat/hxv034
J. Divahar, A. J. Roberts, T. W. Mattner, J. E. Bunder, and I. G. Kevrekidis. Two novel families of multiscale staggered patch schemes efficiently simulate large-scale, weakly damped, linear waves. Comput. Meth. Appl. Mech. Eng. 413 (2023), p. 116133. doi: 10.1016/j.cma.2023.116133. (Cit. on pp. C163, C165, C172).
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J. Maclean, J. E. Bunder, and A. J. Roberts. A toolbox of Equation-Free functions in Matlab/Octave for efficient system level simulation. Numer. Alg. 87 (2021), pp. 1729–1748. doi: 10.1007/s11075-020-01027-z
J. Maclean, J. E. Bunder, I. G. Kevrekidis, and A. J. Roberts. An equation free algorithm accurately simulates macroscale shocks arising from heterogeneous microscale systems. IEEE J. Multiscale Multiphys. Comput. Tech. 6 (2021), pp. 8–15. doi: 10.1109/JMMCT.2021.3054012
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La influencia de la rugosidad en el rendimiento de un perfil aerodinámico a bajo némero de Reynolds
No full textTrabajo de grado - PregradoEn este proyecto se logró identificar la relacion entre la rugosidad superficial de un perfil aerodinámico y el rendimiento del mismo. Con el fin de variar los parámetros geométricos del perfil, se utilizo impresión 3D y se realizaron caracterizaciones a bajo numero de Reynolds para comprobar su comportamiento. Con lo cual, se obtuvieron las graficas de los coeficientes aerodinámicos y la relacion entre los mismos. Con esto, se encontró que la rugosidad afecta las fuerzas de sustentación y arrastre de forma positivas. Sin embargo, no se encontró una rugosidad que mejorar el rendimiento aerodinámico del perfil debido al aumento proporcional de las fuerzas aerodinámicas. Adicionalmente, se diseño un montaje experimental adecuado para medir los diferentes ángulos de ataque.In this project, the relationship between the surface roughness of an airfoil and its performance was identified. In order to vary the geometric parameters of the airfoil, 3D printing was used and low Reynolds number characterizations were performed to check its behavior. As a result, the graphs of the aerodynamic coefficients and the relationship between them were obtained. With this, it was found that the roughness affects the lift and drag forces in a positive way. However, no roughness was found to improve the aerodynamic performance of the airfoil due to the proportional increase of the aerodynamic forces. Additionally, a suitable experimental setup was designed to measure the different angles of attack.Ingeniero MecánicoPregrad
Multicriteria decision making model in the glass waste management in a closed loop supply chain
No full textSe desarrolló un modelo multicriterio para la toma de decisiones en la gestión de residuos de envases de vidrio en una cadena de suministro de ciclo cerrado en Colombia, bajo la mirada del eslabón fabricante, identificando 5 criterios y 25 subcriterios. Luego, se aplicó el método AHP con los actores involucrados en la cadena de suministro. El modelo arrojó que los criterios más importantes son el criterio legal y el social, la mejor alternativa es reciclaje con recolección indirectaA multi-criteria model was developed for the decisionmaking in the management of glass container waste in a closed loop supply chain in Colombia, from the point of view of the manufacturer link, identifying 5 criteria and 25 sub-criteria. Then, the AHP method was applied with the actors involved in the supply chain. The model showed that the most important criteria are the legal and social criteria, the best alternative is recycling with indirect collectionIntroducción. Metodología. Resultados. Conclusiones. Referencias bibliográfica
