Ulf Senechal - Academia.edu (original) (raw)
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Papers by Ulf Senechal
Computational Fluid and Solid Mechanics 2003, 2003
Using a system of reaction cells and mixing cells (RCMCS), based on spatial distributions of velo... more Using a system of reaction cells and mixing cells (RCMCS), based on spatial distributions of velocity, temperature, and density, detailed reaction mechanisms can be solved without convergence problems even in a combustion context. In the presented paper diffusive mixing is introduced to the RCMCS method. The local diffusive exchange is controlled by a local exchange parameter, which can be interpreted as a measure for the turbulence controlled mixing. Numerical aspects and the appropriate application of parallel computing are investigated.
Progress in Computational Fluid Dynamics, An International Journal, 2003
CFD calculations with high demands on the degree of chemical information, such as are needed for ... more CFD calculations with high demands on the degree of chemical information, such as are needed for reasons of environmental protection, continue to be no small challenge. A concept is introduced here which achieves two things to a much greater extent than has previously been the case: the degree to which chemical and fluid dynamics modelling can be separated and the extent to which the algorithm can be used by programmers and end users as a black box. This is realised by translating the fluid dynamics model into a system of reaction cells and mixing cells (RCMCS). In this way, a favourable balance is achieved between the amount of labour invested and the degree of chemical information supplied by the simulation. Among other things, the ability to determine unknown parameters of the chemical reaction mechanisms and the functionality of the system with very large reaction mechanisms has been proven.
Heat and Mass Transfer, 2013
Temporal analysis of products (“TAP”, see Gleaves et al. in Catal Rev Sci Eng 30:49, 1988) is a v... more Temporal analysis of products (“TAP”, see Gleaves et al. in Catal Rev Sci Eng 30:49, 1988) is a valuable tool for characterisation of porous catalytic structures. Established TAP-modelling requires a spatially constant diffusion coefficient and neglect convective flows, which is only valid in Knudsen diffusion regime. A new theoretical model is developed for estimating the number of molecules per pulse to stay in Knudsen diffusion regime under any conditions and at any time. Moreover a new methodology for generating a full three-dimensional geometrical representation of beds is presented and used for numerical simulations. In computational fluid dynamics software (ANSYS CFX® version 14) a transient diffusive transport equation with time-dependent inlet boundary conditions is solved. Three different pellet diameters were investigated with 1E+18 molecules per pulse, which is higher than the limit from the theoretical calculation (about 1E+15). From this results, the distance from inlet can be calculated where the theoretical pressure limit (Kn = 2) is obtained, i.e., from this point to the end of reactor, Knudsen regime can be assumed.
Computational Fluid and Solid Mechanics 2003, 2003
Using a system of reaction cells and mixing cells (RCMCS), based on spatial distributions of velo... more Using a system of reaction cells and mixing cells (RCMCS), based on spatial distributions of velocity, temperature, and density, detailed reaction mechanisms can be solved without convergence problems even in a combustion context. In the presented paper diffusive mixing is introduced to the RCMCS method. The local diffusive exchange is controlled by a local exchange parameter, which can be interpreted as a measure for the turbulence controlled mixing. Numerical aspects and the appropriate application of parallel computing are investigated.
Progress in Computational Fluid Dynamics, An International Journal, 2003
CFD calculations with high demands on the degree of chemical information, such as are needed for ... more CFD calculations with high demands on the degree of chemical information, such as are needed for reasons of environmental protection, continue to be no small challenge. A concept is introduced here which achieves two things to a much greater extent than has previously been the case: the degree to which chemical and fluid dynamics modelling can be separated and the extent to which the algorithm can be used by programmers and end users as a black box. This is realised by translating the fluid dynamics model into a system of reaction cells and mixing cells (RCMCS). In this way, a favourable balance is achieved between the amount of labour invested and the degree of chemical information supplied by the simulation. Among other things, the ability to determine unknown parameters of the chemical reaction mechanisms and the functionality of the system with very large reaction mechanisms has been proven.
Heat and Mass Transfer, 2013
Temporal analysis of products (“TAP”, see Gleaves et al. in Catal Rev Sci Eng 30:49, 1988) is a v... more Temporal analysis of products (“TAP”, see Gleaves et al. in Catal Rev Sci Eng 30:49, 1988) is a valuable tool for characterisation of porous catalytic structures. Established TAP-modelling requires a spatially constant diffusion coefficient and neglect convective flows, which is only valid in Knudsen diffusion regime. A new theoretical model is developed for estimating the number of molecules per pulse to stay in Knudsen diffusion regime under any conditions and at any time. Moreover a new methodology for generating a full three-dimensional geometrical representation of beds is presented and used for numerical simulations. In computational fluid dynamics software (ANSYS CFX® version 14) a transient diffusive transport equation with time-dependent inlet boundary conditions is solved. Three different pellet diameters were investigated with 1E+18 molecules per pulse, which is higher than the limit from the theoretical calculation (about 1E+15). From this results, the distance from inlet can be calculated where the theoretical pressure limit (Kn = 2) is obtained, i.e., from this point to the end of reactor, Knudsen regime can be assumed.