MM
M.C. Mascini
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2 records found
1
Master thesis
(2021)
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M.C. Mascini, A.R.P.J. Vijn, E.S.A.M. Lepelaars, A.W. Heemink, M.B. van Gijzen
Eddy currents are currents which are induced in a conducting object by a varying magnetic field. These currents generate a magnetic field of their own. Modelling this phenomenon constitutes a diverse and challenging set of problems, for which many applications exist. One such application is the degaussing system of a naval ship. To guarantee safety on missions, a ship uses a degaussing system to reduce its magnetic signature. Being able to model the effect of eddy current fields is necessary to improve the accuracy of future degaussing systems.
This thesis will examine how eddy current effects can be modeled, and how such a model can be validated. An analytical solution for a sphere is derived and investigated. A boundary element method (BEM) is implemented, which is able to numerically approximate the electromagnetic fields in terms of the modified magnetic vector potential A* and the reduced magnetic scalar potential. The approximation using the BEM is compared to the analytical solution. The BEM shows promising results, being able to model the shape of the magnetic signature of a sphere accurately. The model is also applied to more realistic geometries resembling naval ships, making it a strong candidate for further development and potential implementation in a future degaussing system. ...
This thesis will examine how eddy current effects can be modeled, and how such a model can be validated. An analytical solution for a sphere is derived and investigated. A boundary element method (BEM) is implemented, which is able to numerically approximate the electromagnetic fields in terms of the modified magnetic vector potential A* and the reduced magnetic scalar potential. The approximation using the BEM is compared to the analytical solution. The BEM shows promising results, being able to model the shape of the magnetic signature of a sphere accurately. The model is also applied to more realistic geometries resembling naval ships, making it a strong candidate for further development and potential implementation in a future degaussing system. ...
Eddy currents are currents which are induced in a conducting object by a varying magnetic field. These currents generate a magnetic field of their own. Modelling this phenomenon constitutes a diverse and challenging set of problems, for which many applications exist. One such application is the degaussing system of a naval ship. To guarantee safety on missions, a ship uses a degaussing system to reduce its magnetic signature. Being able to model the effect of eddy current fields is necessary to improve the accuracy of future degaussing systems.
This thesis will examine how eddy current effects can be modeled, and how such a model can be validated. An analytical solution for a sphere is derived and investigated. A boundary element method (BEM) is implemented, which is able to numerically approximate the electromagnetic fields in terms of the modified magnetic vector potential A* and the reduced magnetic scalar potential. The approximation using the BEM is compared to the analytical solution. The BEM shows promising results, being able to model the shape of the magnetic signature of a sphere accurately. The model is also applied to more realistic geometries resembling naval ships, making it a strong candidate for further development and potential implementation in a future degaussing system.
This thesis will examine how eddy current effects can be modeled, and how such a model can be validated. An analytical solution for a sphere is derived and investigated. A boundary element method (BEM) is implemented, which is able to numerically approximate the electromagnetic fields in terms of the modified magnetic vector potential A* and the reduced magnetic scalar potential. The approximation using the BEM is compared to the analytical solution. The BEM shows promising results, being able to model the shape of the magnetic signature of a sphere accurately. The model is also applied to more realistic geometries resembling naval ships, making it a strong candidate for further development and potential implementation in a future degaussing system.
A turbulent flow is composed of swirling eddies of many sizes. Energy, which is added to the flow at the larger scales, is transferred down through consecutively smaller eddies until the scale is small enough that viscous forces dominate, at which point the energy is dissipated. The mechanism by which energy is transferred down the scales of eddies is generally described as eddy break-up, but the process of eddies breaking into smaller eddies has never been directly observed. The objective of this research is to identify and visualize eddies and their breakage into smaller eddies in numerically simulated isotropic turbulence flows. A corre- lation vector is defined at each point in space, based upon the dot product of velocity over spatial distance. This function shows eddies as the result of correlation over the entire field for each point, in contrast to ear- lier eddy identification techniques which focus only on local properties of the flow, such as kinetic energy magnitude. The resultant correlation field shows blobs of high correlation, which can be interpreted as the kernel of a coherent structure in the flow. These kernels can be seen splitting into smaller kernels over time — an indication of the turbulent energy cascade at work. Making use of the Biot-Savart law, the veloc- ity field associated with a coherent blob of correlation is generated from the associated vorticity field. The reconstructed velocity field is vortex-like in structure, and appears to break into two separate vortices as the kernel separates into two distinct kernels, yielding a visualization of turbulent eddy dynamics in real space — the first step towards the visualization of the turbulent energy cascade.
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A turbulent flow is composed of swirling eddies of many sizes. Energy, which is added to the flow at the larger scales, is transferred down through consecutively smaller eddies until the scale is small enough that viscous forces dominate, at which point the energy is dissipated. The mechanism by which energy is transferred down the scales of eddies is generally described as eddy break-up, but the process of eddies breaking into smaller eddies has never been directly observed. The objective of this research is to identify and visualize eddies and their breakage into smaller eddies in numerically simulated isotropic turbulence flows. A corre- lation vector is defined at each point in space, based upon the dot product of velocity over spatial distance. This function shows eddies as the result of correlation over the entire field for each point, in contrast to ear- lier eddy identification techniques which focus only on local properties of the flow, such as kinetic energy magnitude. The resultant correlation field shows blobs of high correlation, which can be interpreted as the kernel of a coherent structure in the flow. These kernels can be seen splitting into smaller kernels over time — an indication of the turbulent energy cascade at work. Making use of the Biot-Savart law, the veloc- ity field associated with a coherent blob of correlation is generated from the associated vorticity field. The reconstructed velocity field is vortex-like in structure, and appears to break into two separate vortices as the kernel separates into two distinct kernels, yielding a visualization of turbulent eddy dynamics in real space — the first step towards the visualization of the turbulent energy cascade.