The virtual element method for discrete fracture network simulations

In this work, an optimization based approach presented in previous work of the authors for Discrete Fracture Network simulations is coupled with the Virtual Element Method (VEM) for the space discretization of the underlying Darcy law. The great flexibility of the VEM in allowing rather general polygonal elements, allow to easily describe irregular solutions starting from a general triangulation which can be built independently of the mesh on other fractures. Only a partial conformity is in fact obtained with this approach. Numerical results performed on several DFN configurations confirm the viability and efficiency of the resulting method

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study

Background: In 2020, ACIE Appy study showed that COVID-19 pandemic heavily affected the management of patients with acute appendicitis (AA) worldwide, with an increased rate of non-operative management (NOM) strategies and a trend toward open surgery due to concern of virus transmission by laparoscopy and controversial recommendations on this issue. The aim of this study was to survey again the same group of surgeons to assess if any difference in management attitudes of AA had occurred in the later stages of the outbreak. Methods: From August 15 to September 30, 2021, an online questionnaire was sent to all 709 participants of the ACIE Appy study. The questionnaire included questions on personal protective equipment (PPE), local policies and screening for SARS-CoV-2 infection, NOM, surgical approach and disease presentations in 2021. The results were compared with the results from the previous study. Results: A total of 476 answers were collected (response rate 67.1%). Screening policies were significatively improved with most patients screened regardless of symptoms (89.5% vs. 37.4%) with PCR and antigenic test as the preferred test (74.1% vs. 26.3%). More patients tested positive before surgery and commercial systems were the preferred ones to filter smoke plumes during laparoscopy. Laparoscopic appendicectomy was the first option in the treatment of AA, with a declined use of NOM. Conclusion: Management of AA has improved in the last waves of pandemic. Increased evidence regarding SARS-COV-2 infection along with a timely healthcare systems response has been translated into tailored attitudes and a better care for patients with AA worldwide

Mixed Virtual Elements for discrete fracture network simulations

The present work deals with the simulation of the flow in Discrete Fracture Networks (DFN), using the mixed formulation of the Virtual Element Method (VEM) on polygonal conforming meshes. The flexibility of the VEM in handling polygonal meshes is used to easily generate a conforming mesh even in the case of intricate DFNs. Mixed Virtual Elements of arbitrary polynomial accuracy are then used for the discretization of the velocity field. The well posedness of the resulting discrete problem is shown. Numerical results on simple problems are proposed to show convergence properties of the method with respect to known analytic solutions, whereas some tests on fairly complex networks are also reported showing its applicability and effectiveness.Fil: Benedetto, Matías Fernando. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Borio, Andrea. Politecnico di Torino; ItaliaFil: Scialò, Stefano. Politecnico di Torino; Itali

Order preserving SUPG stabilization for the virtual element formulation of advection–diffusion problems

In the framework of the discretization of advection–diffusion problems by means of the Virtual Element Method, we consider stabilization issues. Herein, stabilization is pursued by adding a consistent SUPG-like term. For this approach we prove optimal rates of convergence. Numerical results clearly show the stabilizing effect of the method up to very large Péclet numbers and are in very good agreement with the expected rate of convergence.Fil: Benedetto, Matías Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Berrone, Stefano. Politecnico di Torino; ItaliaFil: Borio, A.. Politecnico di Torino; ItaliaFil: Pieraccini, S.. Politecnico di Torino; ItaliaFil: Scialò, S.. Politecnico di Torino; Itali

Método multiescala concurrente para análisis\nde falla de hormigón.

El uso de esquemas multiescala para el análisis del comportamiento de falla de materiales compuestos permiten\nevaluar los complejos mecanismos de degradación en las diferentes escalas de observación y conseguir información precisa sobre los efectos de estos procesos de degradación de las subescalas en el comportamiento de la respuesta\nmacroscópica.\nEn este trabajo se sigue un nuevo enfoque para el análisis concurrente de falla de materiales que exhiben inclusiones heterogéneas en la escala mesoscópica. Se basa en la combinación de elementos virtuales (VE) y elementos de interfaz (IE) en el marco del enfoque de fisura discreta.Fil: López Rivarola, Felipe. CONICET -Universidad de Buenos Aires. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long" (INTECIN). Buenos Aires; Argentina.Fil: López Rivarola, Felipe. Universidad de Buenos Aires. Facultad de Ingeniería. Buenos Aires; Argentina.Fil: Labanda, Nicolás A.. Universidad de Tucumán. Tucumán; Argentina.Fil: Labanda, Nicolás A. Curtin University. Perth; Australia.Fil: Benedetto, Matías Fernando. University of Queensland. School of Mathematics and Physics. St. Lucia, QLD; Australia.Fil: Etse, Guillermo. CONICET -Universidad de Buenos Aires. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long" (INTECIN). Buenos Aires; Argentina.Fil: Etse, Guillermo. Universidad de Tucumán. Tucumán; Argentina.Fil: Etse, Guillermo. Universidad de Buenos Aires. Facultad de Ingeniería. Buenos Aires; Argentina.<dc:description

A multiscale approach with the Virtual Element Method: Towards a VE 2 setting

A semi-concurrent multi scale approach for heterogeneous media discretized with the Virtual Element Method (VEM) is presented in this work. Extensive numerical results for both the linear diffusion and linear elasticity settings are performed to assess the quality of the discrete solution, highlighting the differences between a mesoscopic and a multiscale approach. The capabilities and advantages of using VEM in semi-concurrent multiscale analyses are demonstrated, especially when dealing with composite materials and inclusions.Fil: Lopez Rivarola, Felipe. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Laboratorio de Métodos Numéricos en Ingeniería; ArgentinaFil: Benedetto, Matías Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Labanda, Nicolás Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Estructuras "Ing. Arturo M. Guzmán"; ArgentinaFil: Etse, Jose Guillermo. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Centro de Métodos Numéricos y Computacionales en Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study (vol 46, pg 2021, 2022)

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