Year: 2023
Author(s): Vasilis Naserentin, Anders Logg, Dag Wästberg
Publication Type: Journal article
Digital Twin Cities Centre (DTCC) Builder is a mesh generator for automatic, efficient, and robust mesh generation for large-scale city modeling and simulation. Using standard and widely available raw data sources in the form of point clouds and cadastral data, DTCC Builder generates high-quality 3D surface and volume meshes, suitable for both visualization and simulation. In particular, DTCC Builder is capable of generating large-scale, conforming tetrahedral volume meshes of cities suitable for finite element (FEM) simulation.
Year: 2023
Author(s): Patricia Vanky, Andreas Mark, Franziska Hunger, Marie Haeger-Eugensson, Joaquim Tarraso, Marco Adelfio, Angela Sasic Kalagasidis, Gaetano Sardina
Publication Type: Journal article
Considering wind, air and heat comfort in designing new urban areas is still a challenge for city planners. Urban heat islands, or the phenomena of locally increased temperatures in urban areas compared to their rural surroundings, are becoming increasingly problematic with global warming and the rise of urbanization. Therefore, new areas must be planned considering appropriate ventilation to mitigate these high-temperature regions and cooling strategies, such as green infrastructures, must be considered. Typically, most of the comfort criteria are evaluated and assessed in the final stages of urban planning when further strategic interventions are no longer possible. Here, a numerical framework is tested that urban planners can use as a future tool to analyze complex fluid dynamics and heat transfer in the early stages of urban planning. The framework solves the RANS equations using an immersed boundary approach to discretize the complex urban topography in a cartesian octree grid. The grid is automatically generated, eliminating the complex pre-processing of urban topographies and making the framework accessible to all users. The results are validated against experimental data from wind tunnel measurements of wind-driven ventilation in street canyons. After validation, we will apply the numerical framework to estimate the wind comfort in an idealized urban area. Finally, guidelines will be provided on the choice of minimum grid sizes required to capture the relevant flow structures inside a canyon accurately.
Year: 2023
Author(s): Carolina Sellin, Minna Karstunen
Publication Type: Paper in proceeding
The initial and strain-induced anisotropic structure, as well as the strain-softening behaviour, of sensitive clay has been long recognized. These soil features, and their subsequent effect on the mobilized strength, are however rarely directly considered in the evaluation of slope stability. This numerical study investigates the influence of 1) Initial anisotropy; 2) Evolving anisotropy and 3) Degradation of the inter-particle bonds (destructuration) due to irrecoverable creep strains on the stability and failure mechanisms of a slope in sensitive clay. The rate-dependent Creep-SCLAY1S model includes these features, and its hierarchical formulation, is exploited to illustrate the effect of these features for a typical slope in the Göta River valley, West Sweden.
Year: 2022
Author(s): Jens Olsson, Mats Ander, Christopher John Kenneth Williams
Publication Type: Paper in proceeding
This paper presents a speculative application of adaptive bone-remodelling to generate porous structures for building components using a numerical meshless method. We hypothesize that such porous structures could then be 3d printed to achieve light weight and material efficient
building components. The meshless model is built up of particles that are connected by arms to their neighbours within a distance called a horizon. The re-modelling adaption is then based on the ratio of arms strain over average arm strain which is mapped to a third-order polynomial function and used to scale the arm stiffness in a way that mimics the resorption and densification of bone tissue. The method is shown to work rather well in the recreation of the structural patterns found in cross section of a femur bone. The translation to a geometry which can be manufactured with additive techniques is not tackled specifically and suggest a direction for further work.
Year: 2022
Author(s): Vasilis Naserentin, Sanjay Somanath, Orfeas Eleftheriou, Anders Logg
Publication Type: Paper in proceeding
Evidently, Smart Cities are on the rise and there is an increasing need for digital twins of these complex environments and their corresponding 3D models. The creation and maintenance of such twins is a time consuming task, since cities are living evolving organisms. In this paper we are presenting work done within the Digital Twin Cities Centre (DTCC) in Sweden in the field of automated 3D city model generation. We showcase a novel method of combining open source and commercial software for creating digital twins of any urban context in a procedural way from raw input data and using Unreal Engine as a visualization front-end. We combine two different workflows, one based on the commercial software suite Feature Manipulation Engine and in parallel we utilize the open source code developed within the Centre, dubbed DTCC Builder. The assets created can be used in urban planning, multiphysics continuum mechanics simulations and for visualization and illustration on a 3D scale. By using, in a complementary way, established commercial software and state of the art open source C++ code we manage to utilize the quality of life features the first provides, while assigning the demanding tasks of comforming mesh generation to the former. The longer term goal is (nearly) real-time mesh digital twinning of any city and user interaction with the 3D assets provided. Copyright (C) 2022 The Authors.
Year: 2022
Author(s): Stoyan Boyukliyski, Dessislava Petrova-Antonova, Sanjay Somanath
Publication Type: Paper in proceeding
In order to aid the decision making process related to the provision of public services as to maximize the benefits for society, it is crucial to evaluate the current social facilities demand in terms of spatial distribution and access. The paper aims to solve this problem by proposing a method for automated assessment of the coverage of public services within an urban region using a capacitated graph. The methodology abstracts residential buildings into demand nodes and public service buildings into supply nodes within a graph and then uses shortest distance calculations in order to balance the two, while prioritizing residential buildings based on distance. The paper is focused on creating a general pipeline that can be used on any type of public services, as long as a certain geospatial and demographic data are available. The method is described without referencing specific tools, but focusing on the general procedure. The procedure is then applied to the whole city of Sofa, focusing on assessing the coverage of kindergartens using the 15 minutes walking distance, followed by a brief discussion of results.
Year: 2022
Author(s): Daniela Maiullari, Alvar Palm, Holger Wallbaum, Liane Thuvander
Publication Type: Paper in proceeding
Among International Energy Agency members, Sweden is one of the upfront countries in implementing energy policies to achieve zero net emissions. Despite having the lowest share of fossil sources in its primary energy supply, becoming carbon neutral by 2045 is a challenging target. To meet the national goal, cities’ roadmaps and strategic plans have a leading role in facilitating the implementation of energy efficiency measures and renewable production systems. However, succeeding in city energy transitions requires envisioning and understanding of risk and vulnerability levels of the new socio-technical energy system. This study presents a review of the City of Gothenburg’s Energy Plan 2022-2030 and discusses potential challenges
for its implementation. Based on a document study, stakeholder workshop, and interviews the research identifies four key aspects: i) the coordination between energy and urban planning, ii) the future stability of district heating and cooling, iii) the balance in electrification of the buildings and transport, iv) communication and tools in decision-making processes. Finally, the study suggests new measures that should be allocated in the plan to guarantee the development of instruments and analysis for addressing the identified challenges.
Year: 2021
Author(s): Johannes Tornborg, Mats Karlsson, Anders Kullingsjö, Minna Karstunen
Publication Type: Journal article
This paper presents a benchmark of a rate-dependent constitutive model for soft soils, implemented in a 2D finite element code, against the response of an instrumented excavation in sensitive clay: Göta Tunnel in Gothenburg. The monitoring data, which comprise time-series of pore water pressures, displacements, earth pressures and strut forces, provide valuable insights of the time-dependent response during the construction period. The long-term response, in terms of the ongoing settlement rates, is assessed using remote sensing data. The results of the numerical simulations demonstrate that the constitutive model, Creep-SCLAY1S, is capable of capturing the observed response. The trends of vertical and horizontal displacements are captured well until the stage of dewatering, and the evolution of pore pressures and earth pressures is computed with high accuracy, excluding peaks in the measurement values arising from pile and rock anchor installation. Most importantly, the results demonstrate that the rate-dependent model enables to model the complete service life of the tunnel, from construction of the excavation to the tunnel operation, with one unified model parameter set. Furthermore, the comparisons highlight the importance of assessing installation effects both in the choice of construction methods and modelling.
Year: 2021
Author(s): Jonathan Edgardo Cohen, Jorge Gil
Publication Type: Journal article
Waste and resources management is one of the domains where urban and regional planning can transition towards a Circular Economy, thus slowing environmental degradation. Improving waste and resources management in cities requires an adequate understanding of multiple systems and how they interact. New technologies contribute to improve waste management and resource efficiency, but knowledge silos hinder the possibility of delivering sound holistic solutions. Furthermore, lack of compatibility between data formats and diverse definitions of the same concept reduces information exchange across different urban domains. This paper addresses the challenge of organising and standardising information about waste and resources management in city regions. Given the amount and variety of data constantly captured, data models and standards are a crucial element of Industry 4.0. The paper proposes an Entity-Relationship Model to harmonise definitions and integrate information on waste and resources management. Furthermore, it helps to formalise the components of the system and their relationships. Semi-structured interviews with government officials, mobile app developers and academics provided insights into the specific system and endorsed the model. Finally, the paper illustrates the translation of the ERM into a relational database schema and instantiates Waste Management and industrial Symbiosis cases in Buenos Aires (ARG) and Helsingborg (SWE) to validate its general applicability. The data model for the Circular Flow of Waste and Resources presented here enhances traditional waste management perspectives by introducing Circular Economy strategies and spatial variables in the model. Thus, this research represents a step towards unlocking the true potential of Industry 4.0.
Year: 2020
Author(s): Jorge Gil
Publication Type: Other text in scientific journal
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