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Emergence of Integrated Water Resources Management: Measuring implementation in Vietnam

Akkerman, M. (author), Khanh, N.T. (author), Witter, M. (author), Rutten, M.M. (author)

Recently, the changes in laws and regulations, such as the revised Law on Water Resources in 2012, have sought to provide a legal framework for the internationally recognized practices of Integrated Water Resources Management (IWRM) in Vietnam. With IWRM being a novel approach for Vietnam, it would be interesting to evaluate how well water...

conference paper 2015

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Machine learning for the prediction of the local drag forces and heat transfer rates in turbulent flows past rough surfaces

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

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Generating and absorbing boundary conditions for combined wave-current simulations

Chang, X. (author), Akkerman, I. (author), Huijsmans, R.H.M. (author), Veldman, A.E.P. (author)

The CFD simulation tool ComFLOW is extended to investigate the characteristics of wave motions in the presence of steady uniform currents. Initially, the inflow boundary is the superposition of waves and current. Effect of the latter on the former is resolved by solving Navier-Stokes equations within the domain as a next step. A Generating and...

conference paper 2016

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Efficient methodology of roll load prediction on 2D bodies in nonlinear flows

Gadi, Ratnakar (author), Huijsmans, R.H.M. (author), Akkerman, I. (author), van 't Veer, A.P. (author)

conference paper 2018

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The influence of thermal contact resistance on the thermal history in laser-assisted fiber placement

Çelik, 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

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Adaptive Variational Multiscale Formulations using the Discrete Germano

Akkerman, I. (author)

A Residual-Based Large-Eddy Simulation (RB-LES) method is developed. This is done by discretizing the Navier-Stokes equations directly. A priori filtering is omitted. Analytical approximation of the subgrid scales results in a unusually-stabilized finite-element method with additional terms arising due to the nonlinearity. This RB-LES method is...

doctoral thesis 2009

document

Inductive inference, theory revision and non-monotonic logic

Akkerman, G.J. (author)

doctoral thesis 1996

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Low-Cost Technology for the Integration of Micro- and Nanochips into Fluidic Systems on Printed Circuit Board: Fabrication Challenges

Palacios-Aguilera, N.B. (author), Bastemeijer, J. (author), Mollinger, J.R. (author), Bossche, A. (author), Mokkapati, V.R.S.S. (author), Visser, H.A. (author), Akkerman, R. (author)

Nowadays, micro- and nanochips are usually fabricated with Silicon and/or glass. A simple, low-cost and reliable integration packaging method that provides flexibility to the incorporation of electronic and fluidic devices into a system has not been fully developed yet. The use of Printed Circuit Board material as substrate to create dry film...

journal article 2012

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The role of continuity in residual-based variational multiscale modeling of turbulence

Akkerman, I. (author), Bazilevs, Y. (author), Calo, V.M. (author), Hughes, T.J.R. (author), Hulshoff, S. (author)

This paper examines the role of continuity of the basis in the computation of turbulent flows. We compare standard finite elements and non-uniform rational B-splines (NURBS) discretizations that are employed in Isogeometric Analysis (Hughes et al. in Comput Methods Appl Mech Eng, 194:4135–4195, 2005). We make use of quadratic discretizations...

journal article 2007

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Low-aspect ratio appendages for wind-assisted ships

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

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The influence of inter-laminar thermal contact resistance on the cooling of material during laser assisted fiber placement

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

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Mesoscale process modeling of a thick pultruded composite with variability in fiber volume fraction

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_f ), which can have a profound effect on process-induced residual stress. Until now, this effect of non-uniform V_f distribution has been hardly addressed in the process models. In...

journal article 2021

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Construction and application of an algebraic dual basis and the Fine-Scale Greens’ Function for computing projections and reconstructing unresolved scales

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

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Saturated transverse permeability of unidirectional rovings for pultrusion: The effect of microstructural evolution through compaction

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

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A novel diffuse-interface model and a fully-discrete maximum-principle-preserving energy-stable method for two-phase flow with surface tension and non-matching densities

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

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Nitsche's method as a variational multiscale formulation and a resulting boundary layer fine-scale model

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

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Machine learning for the prediction of the local skin friction factors and Nusselt numbers in turbulent flows past rough surfaces

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

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Monotone level-sets on arbitrary meshes without redistancing

Akkerman, I. (author)

In this paper we present a level-set approach that addresses two issues that can occur when the level-set approach is used to simulate two-fluid flows in engineering practice.<br/>The first issues is that of smoothing of the Heaviside on arbitrary meshes. It is shown that the Heaviside can be non-smooth on non-uniform meshes. Alternative...

journal article 2017

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Isogeometric analysis of linear free-surface potential flow

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

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A monolithic finite element formulation for the hydroelastic analysis of very large floating structures

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