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Evaluation of a modified reynolds stress model for turbulent dispersed two-phase flows including two-way coupling

Beishuizen, N.A. (author), Naud, B. (author), Roekaerts, D. (author)

journal article 2007

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Vortices, complex flows and inertial particles

Hunt, J.C.R. (author), Delfos, R. (author), Eames, I. (author), Perkins, R.J. (author)

journal article 2007

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Large eddy simulations of targeted electromagnetic control of buoyancy-driven turbulent flow in a slender enclosure

Kenjeres, S. (author)

We conducted a large eddy simulation (LES) of a locally applied electromagnetic control of turbulent thermal convection of an electrically conductive fluid (electrolyte solution) inside of a slender enclosure. Generic configurations, consisting of two or three magnets of opposite polarities located below the lower wall, and two oppositely...

journal article 2009

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Numerical Simulation of Turbulent Flow in Concentric Annuli

Boersma, B.J. (author), Breugem, W.P. (author)

In this paper we consider a fully developed turbulent flow in a round pipe with a small inner annulus. The diameter of the inner annulus is less than 10% of the diameter of the outer pipe. As a consequence, the surface area of the inner pipe compared to the outer pipe is small. The friction exerted by the wall on the flow is proportional to the...

journal article 2010

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Numerical Simulation of Delft-Jet-in-Hot-Coflow (DJHC) Flames Using the Eddy Dissipation Concept Model for Turbulence–Chemistry Interaction

De, A. (author), Oldenhof, E. (author), Sathiah, P. (author), Roekaerts, D. (author)

In this paper, we report results of a numerical investigation of turbulent natural gas combustion for a jet in a coflow of lean combustion products in the Delft-Jet-in-Hot-Coflow (DJHC) burner which emulates MILD (Moderate and Intense Low Oxygen Dilution) combustion behavior. The focus is on assessing the performance of the Eddy Dissipation...

journal article 2011

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The Effect of Variable Air–Fuel Ratio on Thermal NOx Emissions and Numerical Flow Stability in Rotary Kilns Using Non-Premixed Combustion

El Abbassi, M. (author), Lahaye, D.J.P. (author), Vuik, Cornelis (author)

One of the quickest ways to influence both the wall temperature and thermal NOx emissions in rotary kilns is to change the air–fuel ratio (AFR). The normalized counterpart of the AFR, the equivalence ratio, is usually associated with premixed flames and studies of its influence on diffusion flames are inconsistent, depending on the application....

journal article 2021

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Mitigating Thermal NOx by Changing the Secondary Air Injection Channel: A Case Study in the Cement Industry

Lahaye, D.J.P. (author), El Abbassi, M. (author), Vuik, Cornelis (author), Talice, Marco (author), Juretic, F. (author)

This work studies how non-premixed turbulent combustion in a rotary kiln depends on the<br/>geometry of the secondary air inlet channel. We target a kiln in which temperatures can reach values above 1800 degrees Kelvin. Monitoring and possible mitigation of the thermal nitric-oxide (NOx) formation is of utmost importance. The performed reactive...

journal article 2021

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Towards Adaptive Grids for Atmospheric Boundary-Layer Simulations

van Hooft, J.A. (author), Popinet, Stéphane (author), van Heerwaarden, Chiel C. (author), van der Linden, S.J.A. (author), de Roode, S.R. (author), van de Wiel, B.J.H. (author)

We present a proof-of-concept for the adaptive mesh refinement method applied to atmospheric boundary-layer simulations. Such a method may form an attractive alternative to static grids for studies on atmospheric flows that have a high degree of scale separation in space and/or time. Examples include the diurnal cycle and a convective...

journal article 2018

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Two-phase air-water flows in hydraulic jumps at low Froude number: Similarity, scale effects and the need for field observations

Estrella, Jorge (author), Wüthrich, D. (author), Chanson, Hubert (author)

A hydraulic jump is a region of rapidly-varied flow that is extremely turbulent. While the one-dimensional continuity and momentum principles have been successfully applied to express the relationships between upstream and downstream conditions, the three-dimensional equations cannot be resolved without some complicated turbulence closure,...

journal article 2022

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Assessment of turbulent blood flow and wall shear stress in aortic coarctation using image-based simulations

Perinajová, R. (author), Juffermans, J.F. (author), Mercado, Jonhatan Lorenzo (author), Aben, Jean Paul (author), Ledoux, Leon (author), Westenberg, Jos J.M. (author), Lamb, Hildo J. (author), Kenjeres, S. (author)

In this study, we analyzed turbulent flows through a phantom (a 180^∘ bend with narrowing) at peak systole and a patient-specific coarctation of the aorta (CoA), with a pulsating flow, using magnetic resonance imaging (MRI) and computational fluid dynamics (CFD). For MRI, a 4D-flow MRI is performed using a 3T scanner. For CFD, the...

journal article 2021

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Estimating the stability of a bed protection of a weir-mounted tidal turbine

Verbeek, Merel C. (author), Labeur, R.J. (author), Uijttewaal, W.S.J. (author)

Coastal infrastructure, such as bridges and storm surge barriers with weirs, provides an attractive location for harvesting renewable energy using tidal turbines. Often stone layers are applied downstream of coastal infrastructure to protect the sea bed from erosion. However, little is known about the potential effect of tidal energy...

journal article 2020

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XFEM level set-based topology optimization for turbulent conjugate heat transfer problems

Noel, L.F.P. (author), Maute, K. (author)

Solving conjugate heat transfer design problems is relevant for various engineering applications requiring efficient thermal management. Heat exchange between fluid and solid can be enhanced by optimizing the system layout and the shape of the flow channels. As heat is transferred at fluid/solid interfaces, it is crucial to accurately resolve...

journal article 2023

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Delayed blow-up and enhanced diffusion by transport noise for systems of reaction–diffusion equations

Agresti, A. (author)

This paper is concerned with the problem of regularization by noise of systems of reaction–diffusion equations with mass control. It is known that strong solutions to such systems of PDEs may blow-up in finite time. Moreover, for many systems of practical interest, establishing whether the blow-up occurs or not is an open question. Here we...

journal article 2023

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Aortic valve neocuspidization and bioprosthetic valves: Evaluating turbulence haemodynamics

Manchester, Emily Louise (author), Pirola, S. (author), Pirola, Sergio (author), Mastroiacovo, Giorgio (author), Polvani, Gianluca (author), Pontone, Gianluca (author), Xu, Xiao Yun (author)

Aortic valve disease is often treated with bioprosthetic valves. An alternative treatment is aortic valve neocuspidization which is a relatively new reparative procedure whereby the three aortic cusps are replaced with patient pericardium or bovine tissues. Recent research indicates that aortic blood flow is disturbed, and turbulence effects...

journal article 2024

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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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Marangoni driven turbulence in high energy surface melting processes

Kidess, A. (author), Kenjeres, S. (author), Righolt, B.W. (author), Kleijn, C.R. (author)

Experimental observations of high-energy surface melting processes, such as laser welding, have revealed unsteady, often violent, motion of the free surface of the melt pool. Surprisingly, no similar observations have been reported in numerical simulation studies of such flows. Moreover, the published simulation results fail to predict the...

journal article 2016

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Fluctuations of angle of attack and lift coefficient and the resultant fatigue loads for a large Horizontal Axis Wind turbine

Rezaeiha, Abdolrahim (author), Balbino dos Santos Pereira, R. (author), Kotsonis, M. (author)

Unsteady loads are a major limiting factor for further upscaling of HAWTs considering the high costs associated to strict structural requirements. Alleviation of these unsteady loads on HAWT blades, e.g. using active flow control (AFC), is of high importance. In order to devise effective AFC methods, the unsteady loading sources need to be...

journal article 2017

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Scalar statistics in variable property turbulent channel flows

Patel, A. (author), Boersma, B.J. (author), Pecnik, Rene (author)

Direct numerical simulation of fully developed, internally heated channel flows with isothermal walls is performed using the low-Mach-number approximation of Navier-Stokes equation to investigate the influence of temperature-dependent properties on turbulent scalar statistics. Different constitutive relations for density ρ, viscosity μ, and...

journal article 2017

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Driving behaviour at motorway ramps and weaving segments based on empirical trajectory data

van Beinum, A.S. (author), Farah, H. (author), Wegman, F.C.M. (author), Hoogendoorn, S.P. (author)

In the vicinity of ramps, drivers make route choices, change lanes and in most cases also adjust their speeds. This can trigger anticipatory behaviour by the surrounding vehicles, which are also reflected in lane changes and/or changes in speed. This phenomenon is called turbulence and is widely recognised by the scientific literature and...

journal article 2018

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Mechanisms of cross-shore transport and spatial variability of phytoplankton on a rip-channeled beach

Fujimura, Atsushi G. (author), Reniers, A.J.H.M. (author), Paris, Claire B. (author), Shanks, Alan L. (author), MacMahan, Jamie H. (author), Morgan, Steven G. (author)

We investigated whether cross-shore distributions of coastal phytoplankton to the surf zone are controlled by hydrodynamics and their biological characteristics. Data from a rip-channeled beach indicate that concentrations of phytoplankton are higher in the surf zone than offshore. To examine how phytoplankton is transported toward the shore,...

journal article 2018