- document
-
Shrestha, S. (author), Dekker, J. (author), Gerritsma, M.I. (author), Hulshoff, S.J. (author), Akkerman, I. (author)In this paper, we build on the work of Hughes and Sangalli (2007) dealing with the explicit computation of the Fine-Scale Greens’ function. The original approach chooses a set of functionals associated with a projector to compute the Fine-Scale Greens’ function. The construction of these functionals, however, does not generalise to arbitrary...journal article 2024
- document
-
Yuksel, O. (author), Caglar, Baris (author), Broggi, G.C. (author), Michaud, Véronique (author), Akkerman, Remko (author), Baran, Ismet (author)The transverse permeability of roving/tow-based fiber reinforcement is of great importance for accurate flow modeling in the pultrusion process. This study proposes an experimental approach to characterize the roving-based fiber beds' permeability under different compaction conditions. The experimental permeability results of thick roving...journal article 2024
- document
-
Diez Sanhueza, R.G. (author), Akkerman, I. (author), Peeters, J.W.R. (author)Turbulent flows past rough surfaces can create substantial energy losses in engineering equipment. During the last decades, developing accurate correlations to predict the thermal and hydrodynamic behavior of rough surfaces has proven to be a difficult challenge. In this work, we investigate the applicability of convolutional neural networks...journal article 2023
- document
-
ten Eikelder, M.F.P. (author), Van Der Zee, K. G. (author), Akkerman, I. (author), Schillinger, D. (author)Over the last decades, many diffuse-interface Navier-Stokes Cahn-Hilliard (NSCH) models with non-matching densities have appeared in the literature. These models claim to describe the same physical phenomena, yet they are distinct from one another. The overarching objective of this work is to bring all of these models together by laying down...journal article 2023
- document
-
Diez Sanhueza, R.G. (author), Akkerman, I. (author), Peeters, J.W.R. (author)Turbulent flows past rough surfaces can create substantial energy losses in engineering equipment. During the last decades, developing accurate correlations to predict the thermal and hydrodynamic behavior of rough surfaces has proven to be a difficult challenge. In this work, we develop a convolutional neural network architecture to perform...conference paper 2022
- document
-
Colomés, Oriol (author), Verdugo, Francesc (author), Akkerman, I. (author)In this work we present a novel monolithic Finite Element method for the hydroelastic analysis of very large floating structures (VLFS) with arbitrary shapes that is stable, energy conserving, and overcomes the need of an iterative algorithm. The new formulation enables a fully monolithic solution of the linear free-surface flow, described by...journal article 2022
- document
-
van der Kolk, N.J. (author), Akkerman, I. (author), Keuning, J.A. (author), Huijsmans, R.H.M. (author)Wind propulsion for commercial ships has been identified as a key component in the energy transition for the maritime industry. The sailing hybrid ship will operate with leeway (drift) angles to produce a lateral force known as sideforce, for steady operation under sail. In this paper, experimental results for the sailing performance of ships...journal article 2021
- document
-
Çelik, O. (author), Hosseini, S.M.A. (author), Baran, Ismet (author), Grouve, Wouter J.B. (author), Akkerman, Remko (author), Peeters, D.M.J. (author), Teuwen, Julie J.E. (author), Dransfeld, C.A. (author)The effect of thermal contact resistance (TCR) correlated to the degree of intimate contact (DIC) between the incoming tape and the substrate on the temperature history during laser-assisted fiber placement (LAFP) was investigated. A novel experimental methodology was designed to understand the effect with a non-contact method which did not...journal article 2021
- document
-
Yuksel, O. (author), Sandberg, Michael (author), Hattel, Jesper H. (author), Akkerman, Remko (author), Baran, Ismet (author)Pultruded fiber-reinforced polymer composites are susceptible to microstructural nonuni-formity such as variability in fiber volume fraction (V<sub>f</sub> ), which can have a profound effect on process-induced residual stress. Until now, this effect of non-uniform V<sub>f</sub> distribution has been hardly addressed in the process models. In...journal article 2021
- document
-
ten Eikelder, M.F.P. (author), Akkerman, I. (author)Two well-established classes of the interface capturing models are the level-set and phase-field models. Level-set formulations satisfy the maximum principle for the density but are not energy-stable. On the other hand, phase-field models do satisfy the second law of thermodynamics but lack the maximum principle for the density. In this paper...journal article 2021
- document
-
Stoter, Stein K.F. (author), ten Eikelder, M.F.P. (author), de Prenter, Frits (author), Akkerman, I. (author), van Brummelen, E. Harald (author), Verhoosel, Clemens V. (author), Schillinger, Dominik (author)We show that in the variational multiscale framework, the weak enforcement of essential boundary conditions via Nitsche's method corresponds directly to a particular choice of projection operator. The consistency, symmetry and penalty terms of Nitsche's method all originate from the fine-scale closure dictated by the corresponding scale...journal article 2021
- document
-
Anderson, Robert (author), Andrej, Julian (author), Barker, Andrew (author), Bramwell, Jamie (author), Camier, Jean Sylvain (author), Cerveny, Jakub (author), Dobrev, Veselin (author), Dudouit, Yohann (author), Akkerman, I. (author)MFEM is an open-source, lightweight, flexible and scalable C++ library for modular finite element methods that features arbitrary high-order finite element meshes and spaces, support for a wide variety of discretization approaches and emphasis on usability, portability, and high-performance computing efficiency. MFEM's goal is to provide...journal article 2021
- document
-
Damala, Dimitra (author), Verbaas, Frans (author), Bonci, M. (author), Akkerman, I. (author), Hopman, J.J. (author)What it is Broaching-to?<br/>When it can occur?<br/>What can happen if it happens?<br/>What is known about it?<br/>How it can be investigated further?<br/>Practical ways to prevent it in design and in operationreport 2020
- document
-
The influence of thermal contact resistance on the thermal history in laser-assisted fiber placementÇelik, O. (author), Amin Hosseini2, S.M. (author), Baran, İsmet (author), Grouve, Wouter J B (author), Akkerman, Remko (author), Peeters, D.M.J. (author), Teuwen, Julie J.E. (author), Dransfeld, C.A. (author)The temperature history during the laser assisted fiber placement (LAFP) process is very important since it significantly influences the final quality of the structure. Air pockets between subsequent plies, caused by the lack of intimate contact, act as insulators and reduce the through-thickness heat transfer. This phenomenon is commonly...conference paper 2020
- document
-
Akkerman, I. (author), Meijer, J. H.A. (author), ten Eikelder, M.F.P. (author)This paper presents a novel variational formulation to simulate linear free-surface flow. The variational formulation is suitable for higher-order finite elements and higher-order and higher-continuity shape functions as employed in Isogeometric Analysis (IGA). The novel formulation combines the interior and free-surface problems in one...journal article 2020
- document
-
ten Eikelder, M.F.P. (author), Bazilevs, Y. (author), Akkerman, I. (author)In this paper we show that the variational multiscale method together with the variation entropy concept form the underlying theoretical framework of discontinuity capturing. The variation entropy [M.F.P. ten Eikelder and I. Akkerman, Comput. Methods Appl. Mech. Engrg. 355 (2019) 261-283] is the recently introduced concept that equips total...journal article 2020
- document
-
Akkerman, I. (author), ten Eikelder, M.F.P. (author)This paper presents a new monolithic free-surface formulation that exhibits correct kinetic and potential energy behavior. We focus in particular on the temporal energy behavior of two-fluids flow with varying densities. Correct energy behavior here means that the actual energy evolution of the numerical solution matches the evolution as...journal article 2019
- document
-
ten Eikelder, M.F.P. (author), Akkerman, I. (author)This paper presents the notion of a variation entropy. This concept is an entropy framework for the gradient of the solution of a conservation law instead of on the solution itself. It appears that all semi-norms are admissible variation entropies. This provides insight into the total variation diminishing property and justifies it from...journal article 2019
- document
-
Helgedagsrud, Tore (author), Akkerman, I. (author), Bazilevs, Yuri (author), Mathisen, Kjell (author), Øiseth, Ole (author)Computational fluid dynamics (CFD) and fluid–structure interaction (FSI) are growing disciplines in the aeroelastic analysis and design of long-span bridges, which, with their bluff body characteristics, offer major challenges to efficient simulation. In this paper, we employ isogeometric analysis (IGA) based on nonuniform rational B-splines ...journal article 2019
- document
- Gadi, Ratnakar (author), Huijsmans, R.H.M. (author), Akkerman, I. (author), van 't Veer, A.P. (author) conference paper 2018