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Browsing by Author "Bogaers, Alfred EJ"

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A comparison of different CFD and Gaussian dispersion models

Author: Bogaers, Alfred EJ ; Jansen van Rensburg, GJ Date: Sep 2018 In this paper we investigate different numerical techniques to approximate and model gas dispersion, with a primary focus on modelling the buoyancy effects of dense gasses. We compare the popular Gaussian dispersion model with three different ... Read more
A comparison of different quasi-newton acceleration methods for partitioned multi-physics codes

Author: Haelterman, R ; Bogaers, Alfred EJ ; Degroote, J Date: Feb 2018 In many cases, different physical systems interact, which translates to coupled mathematical models. We only focus on methods to solve (strongly) coupled problems with a partitioned approach, i.e. where each of the physical problems is solved ... Read more
Coupling of partitioned physics codes with quasi-Newton methods

Author: Haelterman, R ; Bogaers, Alfred EJ ; Degroote, J ; Cracana, S Date: Mar 2017 Many physics problems can only be studied by coupling various numerical codes, each modeling a subaspect of the physics problem that is addressed. Often, each of these codes needs to be considered as a black box, either because the codes were ... Read more
Energy usage optimisation of heavy haul freight trains

Author: Bogaers, Alfred EJ ; Botha, N Date: Oct 2016 The aim of this paper is to outline a preliminary investigation into an energy optimisation model with the aim of eventually being incorporated into a real-time driver assist program. A significant portion of the South African economy is ... Read more
An evaluation of quasi-Newton methods for application to FSI problems involving free surface flow and solid body contact

Author: Bogaers, Alfred EJ ; Kok, S ; Reddy, BD ; Franze, T Date: Sep 2016 The design of coupling algorithms for partitioned fluid–structure interaction (FSI) simulations are typically validated on FSI problems involving large deformations of thin elastic structures with large added mass ratios. A large number of ... Read more
Extending the robustness and efficiency of artificial compressibility for partitioned fluid-structure interactions

Author: Bogaers, Alfred EJ ; Kok, S ; Reddy, BD ; Franz, T Date: Jan 2015 In this paper we introduce the idea of combining artificial compressibility (AC) with quasi-Newton (QN) methods to solve strongly coupled, fully/quasi-enclosed fluid-structure interaction (FSI) problems. Partitioned, incompressible, FSI based ... Read more
Implementation of a visco-plastic sea ice model into OpenFOAM

Author: Bogaers, Alfred EJ ; Jansen van Rensburg, GJ ; Marquart, R ; Skatulla, S Date: Sep 2018 In this paper, we outline the implementation of Hibler’s visco-plastic (VP) sea ice model into OpenFOAM, an opensource finite-volume modelling toolkit. Hibler’s visco-plastic model is arguably the most widely used description of sea ice ... Read more
Improved accuracy considerations in Radial Basis Function surrogate models for variable resolution, scale, dimension and discontinuity

Author: Jansen van Rensburg, Gerhardus J ; Bogaers, Alfred EJ Date: Sep 2018 Surrogate- or metamodels approximate and so reduce the computational cost associated with evaluating computer experiments of interest over a set of design variables. Radial Basis Functions (RBFs) are a popular metamodel choice due to its ease ... Read more
Improving the performance of the partitioned QN-ILS procedure for fluid-structure interaction problems: filtering

Author: Haelterman, R ; Bogaers, Alfred EJ ; Uekermann, B ; Scheufele, K ; Mehl, M Date: Jul 2016 The Quasi-Newton Inverse Least Squares method has become a popular method to solve partitioned interaction problems. Its performance can be enhanced by using information from previous time-steps if care is taken of the possible ill-conditioning ... Read more
Interface information transfer between non-matching, nonconforming interfaces using radial basis function interpolation

Author: Bogaers, Alfred EJ ; Kok, S ; Reddy, BD ; Franz, T Date: Oct 2016 In this paper we outline the use of radial basis function interpolation (RBF) to transfer information across non-matching and nonconforming interface meshes, with particular focus to partitioned fluid-structure interactions (FSI). In general, ... Read more
Inverse parameter identification for a branching 1D arterial network

Author: Bogaers, Alfred EJ ; Kok, S ; Reddy, BD ; Fran, T Date: Jul 2012 In this paper we investigate the invertability of a branching 1D arterial blood flow network. We limit our investigation to a single bifurcating vessel, where the material properties, unloaded areas and variables characterizing the input and ... Read more
Numerical simulation of plastic deformation and mechanical response of strip rolled aluminium alloys

Author: Jansen van Rensburg, Gerhardus J ; Bogaers, Alfred EJ Date: Oct 2018 During the optimal design and simulation of machining or forming processes, detailed simulation of structural response is typically required for use in Finite Element Analysis (FEA). In this study, the bulk temperature and rate dependent ... Read more
Proceedings of the 2018 International Women in Science Without Borders (WISWB) – Indaba

Author: Burke, Michael G ; Maphanga, Regina R ; Jansen van Rensburg, Gerhardus J ; Bogaers, Alfred EJ ; Das, Sonali Date: Jun 2018 The 2nd International Women in Science Without Borders (WISWB) Indaba brings the WISWB series from the north of the African continent where the inaugural chapter was held in Egypt in 2017, to the very south of the African continent, Johannesburg, ... Read more
Quasi-Newton methods for implicit black-box FSI coupling

Author: Bogaers, Alfred EJ ; Kok, S ; Reddy, BD ; Franz, T Date: Sep 2014 In this paper we introduce a new multi-vector update quasi-Newton (MVQN) method for implicit coupling of partitioned, transient FSI solvers. The new quasi-Newton method facilitates the use of 'black-box' field solvers and under certain ... Read more
Quasi-Newton methods for the acceleration of multi-physics codes

Author: Haelterman, R ; Bogaers, Alfred EJ ; Degroote, J ; Boutet, N Date: Aug 2017 Often in nature different physical systems interact which translates to coupled mathematical models. Even if powerful solvers often already exist for problems in a single physical domain (e.g. structural or fluid problems), the development ... Read more
Reduced order modelling techniques for mesh movement strategies as applied to fluid structure interactions

Author: Bogaers, Alfred EJ ; Kok, S ; Malan, AG Date: Jan 2010 In this paper, we implement the method of Proper Orthogonal Decomposition (POD) to generate a reduced order model (ROM) of an optimization based mesh movement technique. In the study it is shown that POD can be used effectively to generate a ... Read more
Strongly coupled partitioned FSI using proper orthogonal decomposition

Author: Bogaers, Alfred EJ ; Kok, S ; Franz, T Date: Dec 2012 In this paper we present a strong coupling algorithm for partitioned fluid-structure interactions which can be applied to black-box field solvers. The coupling algorithm constructs an approximate interface Jacobian of the coupled fluid-structure ... Read more
Towards the development of a fully coupled arterial-venous 1D model: suitability of using a 1D finite volume method with staggered spatial discretization

Author: Bogaers, Alfred EJ ; De Villiers, AM ; Kok, S ; Ubbink, O ; Franz, T ; Reddy, BD ; Du Toit, CG Date: Jul 2012 In this paper we outline the development of a 1D finite volume model to solve for blood flow through the arterial system. The model is based on a staggered spatial discretization which leads to a stable solution scheme. This scheme can ... Read more
Treatment of fully enclosed FSI using artificial compressibility

Author: Bogaers, Alfred EJ ; Kok, S ; Reddy, BD ; Franz, T Date: Jul 2013 In recent years a great deal of advances have been made with respect to Dirichlet-Neuman (DN) partitioned fluid-structure interaction (FSI) solvers. Problems of varying degrees of complexity can be solved with reasonable efficiencies through ... Read more
Using linkography to explore novice designers’ design choices during a STEM task

Author: Blom, N ; Haupt, G ; Bogaers, Alfred EJ Date: Jun 2018 One of the characteristics of the 21st century is the increase in the information sources available to designers to make their design decisions. However, there is much debate about designers' choice of information that enables them to design ... Read more

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