J. Vierendeels | Ghent University (original) (raw)

Papers by J. Vierendeels

Research paper thumbnail of An extension of the preconditioned advection upstream splitting method for 3D two-phase flow calculations in circulating fluidized beds

Computers & Chemical Engineering, 2002

For the calculation of gas Á/solid flow in circulating fluidized beds, a Eulerian Á/Eulerian appr... more For the calculation of gas Á/solid flow in circulating fluidized beds, a Eulerian Á/Eulerian approach is taken. An integration scheme based on dual time stepping and a finite volume technique is developed and implemented in 3D. The inviscid part of the equations is treated following an extension of the preconditioned advection upstream splitting method (AUSMP) to two-phase flows. Calculations on an industrial size straight riser are performed. The influence of the inelasticity of particle Á/particle collisions on the stability of the flow is investigated. Further, the effects of a double abrupt side outlet configuration are shown. #

Research paper thumbnail of Interaction of a H2O/Ar Plasma Jet with Nitrogen Atmosphere: Effect of the Method for Calculating Thermophysical Properties of the Gas Mixture on the Flow Field

Plasma Chemistry and Plasma Processing

The effect of calculating thermodynamic and transport properties of a gas mixture with mixing rul... more The effect of calculating thermodynamic and transport properties of a gas mixture with mixing rules on the flow field in the modeling of a thermal plasma jet was studied. A 3D large eddy simulation model of a non-transferred direct current hybrid water/argon plasma torch issuing in nitrogen atmosphere at 400 K was developed to compare three different models for the calculation of transport and thermodynamic properties of the ternary gas mixture. In the first model, thermodynamic and transport properties of the pure gases are used with mixing rules to estimate the mixture properties. In the second model, the properties of plasma gas (Ar/H2O) are calculated rigorously and mixing rules are used for estimating the properties of the mixture of plasma gas and nitrogen. In the third model, the thermodynamic and transport properties of the ternary gas mixture are calculated rigorously without any mixing rules. From numerical results, the error introduced by using mixing rules was evaluated ...

Research paper thumbnail of Coupled Electromagnetic and Thermal Analysis of an Axial Flux PM Machine

IEEE Transactions on Magnetics, 2015

Research paper thumbnail of Validation of a CFD model for flow in meandering rivers using an experimental test-setup: first results

Advances in Fluid Mechanics VII, 2008

A 3D Reynolds Averaged Navier, Stokes (RANS) model of a meandering channel with rectangular cross... more A 3D Reynolds Averaged Navier, Stokes (RANS) model of a meandering channel with rectangular cross-section has been developed using the commercial software package FLUENT 6.2. This model solves the 3D Navier-Stokes equations using the PISO scheme for the pressure-...

Research paper thumbnail of Centrifugal effects on coaxial cylinders concrete tribometer

ABSTRACT Concrete pumping has become a widely applied placing technique. However, the pumping pre... more ABSTRACT Concrete pumping has become a widely applied placing technique. However, the pumping pressure estimation which is based on the rheological and tribological properties of concretes has not been well optimized. Due to its typical rheological properties, the traditional concrete flows in a pipe only by sliding on the pipe wall. This movement is governed by the local velocities developed in the slip layer which is situated at the concrete-wall interface. As a result, the slip layer thickness and rheological properties become the determining factors on the flow of the traditional concrete in the pipe. In order to study the behavior of the slip layer, a coaxial cylinders tribometer has been developed. This paper shows the influences of the eccentricity effects on the overestimation of the slip layer thickness. This overestimation results an incorrect prediction of the flow profile and the pumping pressure calculation. A modification on the working principle of the tribometer is suggested and validated by experimentations.

Research paper thumbnail of Effect of lubrication layer on velocity profile of concrete in a pumping pipe

Research paper thumbnail of Computational fluid dynamics calibration of Tattersall MK-II type rheometer for concrete

Research paper thumbnail of Non-stationary two-stage relaxation based on the principle of aggregation multi-grid

Computational Fluid Dynamics 2006, 2009

We propose an automatization procedure to find an optimal value of the parameter used in some rel... more We propose an automatization procedure to find an optimal value of the parameter used in some relaxation schemes. The basis of the method is formed by an aggregation-type procedure into a single aggregate and is meant to be applicable as a patch for existing codes.

Research paper thumbnail of CFD analysis and optimization of a liquid lead–bismuth loop target for ISOL facilities

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2015

ABSTRACT In the context of the forthcoming next generation of Radioactive Ion Beams (RIBs) facili... more ABSTRACT In the context of the forthcoming next generation of Radioactive Ion Beams (RIBs) facilities based on an Isotope Separation On Line (ISOL) method, the development of production targets capable of dissipating the high power deposited by the primary beam is a major challenge. The concept of a high-power target based on a liquid Pb-Bi loop incorporating a heat-exchanger and a diffusion chamber was proposed within EURISOL DS and is being developed within the LIEBE1 project. Due to the non-static character of the target, specific hydrodynamics issues are of concern. In this paper, these issues are studied mostly based on three-dimensional (3D) Computational Fluid Dynamics analysis of the flow of the Lead Bismuth Eutectic (LBE) target, resulting in optimized designs. The concept and hydrodynamic challenges of generating RIBs from a liquid-metal-loop target irradiated with a high-power primary beam are presented. The optimization of the target design has been conducted keeping in mind the need for a fast and efficient release of short-lived isotopes.

Research paper thumbnail of Investigation of glucose diffusion using an optofluidic silicon chips

Research paper thumbnail of Velocity profile of self compacting concrete and traditional concrete flowing in a half open pipe

ABSTRACT The behavior of concrete flowing in a pipe is a key factor for mastering the concrete pu... more ABSTRACT The behavior of concrete flowing in a pipe is a key factor for mastering the concrete pumping technique. Due to the non-homogeneity of concrete, the concentration of particles (aggregate, sand, cement…) is not the same everywhere in the pipe. Particularly in the highly sheared zone near the wall, the concentration of coarse particles is much lower than that in the bulk. As a result, the rheological properties across the cross section vary with the distance from the wall. This phenomenon affects directly the velocity profile across the section. However, the velocity profile of concrete flowing in a pipe has never been quantitatively measured. This paper shows an experimental method to accurately measure the velocity profile. On the other hand, the influence of the variation of the rheological properties on the velocity profile across the pipe is also studied. Finally, a comparison between experimental analyses and numerical simulations shows reasonable correlation. This paper concentrates on the difference between the flow of a self-compacting concrete and that of a traditional concrete based on their different rheological properties.

Research paper thumbnail of Fsi coupling techniques based on sensitivities

Research paper thumbnail of Numerical simulation of heat transfer of turbulent impinging jets with two‐equation turbulence models

International Journal of Numerical Methods for Heat & Fluid Flow, 2003

A numerical scheme that has already proved to be efficient and accurate for laminar heat transfer... more A numerical scheme that has already proved to be efficient and accurate for laminar heat transfer is extended for turbulent, axisymmetric heat transfer calculations. The extended scheme is applied to the steady-state heat transfer of axisymmetric turbulent jets, impinging onto a flat plate. Firstly, the low-Reynolds version of the standard k-ɛ model is employed. As is well known, the classical

Research paper thumbnail of Inverse modelling of an aneurysm's elasticity using surrogate-based optimization of a three-dimensional fluidstructure interaction simulation

Research paper thumbnail of A multigrid method for viscous incompressible and low speed compressible flows on high aspect ratio grids

Lecture Notes in Physics, 1998

Discretization of viscous incompressible and viscous low Mach number flows often leads to a syste... more Discretization of viscous incompressible and viscous low Mach number flows often leads to a system of equations which is difficult to solve. This has two reasons: first, high aspect ratio grids result in a numerically-anisotropic behaviour of the diffusive and acoustic terms and second, especially in low Mach number flow, the ratio of the eigenvalues of the inviscid system may become very high. We implemented a new discretization method, using an explicit third order discretization for the convective part, a line implicit central discretization for the acoustic part and for the diffusive part. The lines are chosen in the direction of the gridpoints with shortest connection. The preconditioned semi-implicit line method is used in multistage form because of the explicit third order discretization of the convective part. Multigrid is used as acceleration technique. It is shown in the paper that the convergence is very good, independent of the grid aspect ratio and the Mach number.

Research paper thumbnail of Treatment of source terms and high aspect ratio meshes in turbulence modelling

14th Computational Fluid Dynamics Conference, 1999

Research paper thumbnail of Computational Prediction Ofwind Induced Virations in Silo Groups Using 2D and 3D CFD Simulations

Proceedings of 10th World Congress on Computational Mechanics, 2014

Research paper thumbnail of Progress in the experimental study of dc electrical breakdown in bubbles

Research paper thumbnail of A multiphysics computer modeling framework in support of the quest for reliable and robust local arterial stiffness assessment

Research paper thumbnail of Fluid-Structure Interaction Coupling Techniques Based on Sensitivities

Proceedings of the Sixth International Conference on Engineering Computational Technology, 2008

ABSTRACT

Research paper thumbnail of An extension of the preconditioned advection upstream splitting method for 3D two-phase flow calculations in circulating fluidized beds

Computers & Chemical Engineering, 2002

For the calculation of gas Á/solid flow in circulating fluidized beds, a Eulerian Á/Eulerian appr... more For the calculation of gas Á/solid flow in circulating fluidized beds, a Eulerian Á/Eulerian approach is taken. An integration scheme based on dual time stepping and a finite volume technique is developed and implemented in 3D. The inviscid part of the equations is treated following an extension of the preconditioned advection upstream splitting method (AUSMP) to two-phase flows. Calculations on an industrial size straight riser are performed. The influence of the inelasticity of particle Á/particle collisions on the stability of the flow is investigated. Further, the effects of a double abrupt side outlet configuration are shown. #

Research paper thumbnail of Interaction of a H2O/Ar Plasma Jet with Nitrogen Atmosphere: Effect of the Method for Calculating Thermophysical Properties of the Gas Mixture on the Flow Field

Plasma Chemistry and Plasma Processing

The effect of calculating thermodynamic and transport properties of a gas mixture with mixing rul... more The effect of calculating thermodynamic and transport properties of a gas mixture with mixing rules on the flow field in the modeling of a thermal plasma jet was studied. A 3D large eddy simulation model of a non-transferred direct current hybrid water/argon plasma torch issuing in nitrogen atmosphere at 400 K was developed to compare three different models for the calculation of transport and thermodynamic properties of the ternary gas mixture. In the first model, thermodynamic and transport properties of the pure gases are used with mixing rules to estimate the mixture properties. In the second model, the properties of plasma gas (Ar/H2O) are calculated rigorously and mixing rules are used for estimating the properties of the mixture of plasma gas and nitrogen. In the third model, the thermodynamic and transport properties of the ternary gas mixture are calculated rigorously without any mixing rules. From numerical results, the error introduced by using mixing rules was evaluated ...

Research paper thumbnail of Coupled Electromagnetic and Thermal Analysis of an Axial Flux PM Machine

IEEE Transactions on Magnetics, 2015

Research paper thumbnail of Validation of a CFD model for flow in meandering rivers using an experimental test-setup: first results

Advances in Fluid Mechanics VII, 2008

A 3D Reynolds Averaged Navier, Stokes (RANS) model of a meandering channel with rectangular cross... more A 3D Reynolds Averaged Navier, Stokes (RANS) model of a meandering channel with rectangular cross-section has been developed using the commercial software package FLUENT 6.2. This model solves the 3D Navier-Stokes equations using the PISO scheme for the pressure-...

Research paper thumbnail of Centrifugal effects on coaxial cylinders concrete tribometer

ABSTRACT Concrete pumping has become a widely applied placing technique. However, the pumping pre... more ABSTRACT Concrete pumping has become a widely applied placing technique. However, the pumping pressure estimation which is based on the rheological and tribological properties of concretes has not been well optimized. Due to its typical rheological properties, the traditional concrete flows in a pipe only by sliding on the pipe wall. This movement is governed by the local velocities developed in the slip layer which is situated at the concrete-wall interface. As a result, the slip layer thickness and rheological properties become the determining factors on the flow of the traditional concrete in the pipe. In order to study the behavior of the slip layer, a coaxial cylinders tribometer has been developed. This paper shows the influences of the eccentricity effects on the overestimation of the slip layer thickness. This overestimation results an incorrect prediction of the flow profile and the pumping pressure calculation. A modification on the working principle of the tribometer is suggested and validated by experimentations.

Research paper thumbnail of Effect of lubrication layer on velocity profile of concrete in a pumping pipe

Research paper thumbnail of Computational fluid dynamics calibration of Tattersall MK-II type rheometer for concrete

Research paper thumbnail of Non-stationary two-stage relaxation based on the principle of aggregation multi-grid

Computational Fluid Dynamics 2006, 2009

We propose an automatization procedure to find an optimal value of the parameter used in some rel... more We propose an automatization procedure to find an optimal value of the parameter used in some relaxation schemes. The basis of the method is formed by an aggregation-type procedure into a single aggregate and is meant to be applicable as a patch for existing codes.

Research paper thumbnail of CFD analysis and optimization of a liquid lead–bismuth loop target for ISOL facilities

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2015

ABSTRACT In the context of the forthcoming next generation of Radioactive Ion Beams (RIBs) facili... more ABSTRACT In the context of the forthcoming next generation of Radioactive Ion Beams (RIBs) facilities based on an Isotope Separation On Line (ISOL) method, the development of production targets capable of dissipating the high power deposited by the primary beam is a major challenge. The concept of a high-power target based on a liquid Pb-Bi loop incorporating a heat-exchanger and a diffusion chamber was proposed within EURISOL DS and is being developed within the LIEBE1 project. Due to the non-static character of the target, specific hydrodynamics issues are of concern. In this paper, these issues are studied mostly based on three-dimensional (3D) Computational Fluid Dynamics analysis of the flow of the Lead Bismuth Eutectic (LBE) target, resulting in optimized designs. The concept and hydrodynamic challenges of generating RIBs from a liquid-metal-loop target irradiated with a high-power primary beam are presented. The optimization of the target design has been conducted keeping in mind the need for a fast and efficient release of short-lived isotopes.

Research paper thumbnail of Investigation of glucose diffusion using an optofluidic silicon chips

Research paper thumbnail of Velocity profile of self compacting concrete and traditional concrete flowing in a half open pipe

ABSTRACT The behavior of concrete flowing in a pipe is a key factor for mastering the concrete pu... more ABSTRACT The behavior of concrete flowing in a pipe is a key factor for mastering the concrete pumping technique. Due to the non-homogeneity of concrete, the concentration of particles (aggregate, sand, cement…) is not the same everywhere in the pipe. Particularly in the highly sheared zone near the wall, the concentration of coarse particles is much lower than that in the bulk. As a result, the rheological properties across the cross section vary with the distance from the wall. This phenomenon affects directly the velocity profile across the section. However, the velocity profile of concrete flowing in a pipe has never been quantitatively measured. This paper shows an experimental method to accurately measure the velocity profile. On the other hand, the influence of the variation of the rheological properties on the velocity profile across the pipe is also studied. Finally, a comparison between experimental analyses and numerical simulations shows reasonable correlation. This paper concentrates on the difference between the flow of a self-compacting concrete and that of a traditional concrete based on their different rheological properties.

Research paper thumbnail of Fsi coupling techniques based on sensitivities

Research paper thumbnail of Numerical simulation of heat transfer of turbulent impinging jets with two‐equation turbulence models

International Journal of Numerical Methods for Heat & Fluid Flow, 2003

A numerical scheme that has already proved to be efficient and accurate for laminar heat transfer... more A numerical scheme that has already proved to be efficient and accurate for laminar heat transfer is extended for turbulent, axisymmetric heat transfer calculations. The extended scheme is applied to the steady-state heat transfer of axisymmetric turbulent jets, impinging onto a flat plate. Firstly, the low-Reynolds version of the standard k-ɛ model is employed. As is well known, the classical

Research paper thumbnail of Inverse modelling of an aneurysm's elasticity using surrogate-based optimization of a three-dimensional fluidstructure interaction simulation

Research paper thumbnail of A multigrid method for viscous incompressible and low speed compressible flows on high aspect ratio grids

Lecture Notes in Physics, 1998

Discretization of viscous incompressible and viscous low Mach number flows often leads to a syste... more Discretization of viscous incompressible and viscous low Mach number flows often leads to a system of equations which is difficult to solve. This has two reasons: first, high aspect ratio grids result in a numerically-anisotropic behaviour of the diffusive and acoustic terms and second, especially in low Mach number flow, the ratio of the eigenvalues of the inviscid system may become very high. We implemented a new discretization method, using an explicit third order discretization for the convective part, a line implicit central discretization for the acoustic part and for the diffusive part. The lines are chosen in the direction of the gridpoints with shortest connection. The preconditioned semi-implicit line method is used in multistage form because of the explicit third order discretization of the convective part. Multigrid is used as acceleration technique. It is shown in the paper that the convergence is very good, independent of the grid aspect ratio and the Mach number.

Research paper thumbnail of Treatment of source terms and high aspect ratio meshes in turbulence modelling

14th Computational Fluid Dynamics Conference, 1999

Research paper thumbnail of Computational Prediction Ofwind Induced Virations in Silo Groups Using 2D and 3D CFD Simulations

Proceedings of 10th World Congress on Computational Mechanics, 2014

Research paper thumbnail of Progress in the experimental study of dc electrical breakdown in bubbles

Research paper thumbnail of A multiphysics computer modeling framework in support of the quest for reliable and robust local arterial stiffness assessment

Research paper thumbnail of Fluid-Structure Interaction Coupling Techniques Based on Sensitivities

Proceedings of the Sixth International Conference on Engineering Computational Technology, 2008

ABSTRACT