The Experts below are selected from a list of 188388 Experts worldwide ranked by ideXlab platform
Helene Posson - One of the best experts on this subject based on the ideXlab platform.
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the modified myers Boundary Condition for swirling flow
Journal of Fluid Mechanics, 2018Co-Authors: James R Mathews, Vianney Masson, Helene PossonAbstract:This paper gives a modified Myers Boundary Condition in swirling inviscid flow, which differs from the standard Myers Boundary Condition by assuming a small but non-zero Boundary layer thickness. The new Boundary Condition is derived and is shown to have the correct quadratic error behaviour with Boundary layer thickness and also to agree with previous results when the swirl is set to zero. The Boundary Condition is initially derived for swirling flow with constant azimuthal velocity, but easily extends to radially varying swirling flow, with terms depending on the Boundary layer model. The modified Myers Boundary Condition is then given in the time domain rather than in the frequency domain. The effect of the Boundary layer profile is then considered, and shown to be small compared to the Boundary layer thickness. The Boundary Condition is then used to analyse the eigenmodes and Green’s function in a realistic flow. Modelling the thickness of the Boundary layer properly is shown to be essential in order to get accurate results.
Jianming Jin - One of the best experts on this subject based on the ideXlab platform.
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an accurate waveguide port Boundary Condition for the time domain finite element method
IEEE Antennas and Propagation Society International Symposium, 2005Co-Authors: Zheng Lou, Jianming JinAbstract:In this paper, we present a generalized multimodal absorbing Boundary Condition formulated for three-dimensional vector TDFEM analysis for waveguide structures. The proposed Boundary Condition, which we refer to as waveguide port Boundary Condition (WPBC), is capable of perfectly absorbing both propagating and evanescent modes incident on a waveguide port with an arbitrary cross section. The formulation is based on the multimodal expansion in the frequency domain. The corresponding frequency operators are then transformed to the time domain to construct a time-domain Boundary Condition. The formulations for the overall TDFEM system are given and a numerical example for a waveguide discontinuity problems is presented
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an accurate waveguide port Boundary Condition for the time domain finite element method
IEEE Transactions on Microwave Theory and Techniques, 2005Co-Authors: Zheng Lou, Jianming JinAbstract:This paper presents an accurate time-domain waveguide port Boundary Condition (WPBC) that can be used as a mesh truncation Boundary Condition to terminate a finite-element mesh. The formulation for deriving the Boundary Condition is based on multimodal expansion, and thus is related to the modal absorbing Boundary Conditions developed for the finite-difference time-domain method. The Boundary Condition is formulated for the general three-dimensional analysis of waveguides with an arbitrary cross section. All waveguide modes, including transverse electromagnetic, transverse electric, and transverse magnetic modes, are accounted for in the Boundary Condition in a unified formulation. Both propagating and evanescent modes can be properly absorbed. The proposed formulation is validated by numerical examples, and the accuracy and stability of the algorithm are investigated.
Christoph R Muller - One of the best experts on this subject based on the ideXlab platform.
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a dirichlet Boundary Condition for the thermal lattice boltzmann method
International Journal of Multiphase Flow, 2020Co-Authors: Y Chen, Christoph R MullerAbstract:Abstract In this work we introduce a Boundary Condition for thermal lattice Boltzmann simulations that contain a Dirichlet Boundary Condition by bouncing back the non-equilibrium distribution of the energy distribution function. To this end the thermal lattice Boltzmann equation is modified by introducing an additional collision term that takes into account the thermal diffusivity and local solid volume fraction of a lattice (partially) covered by the solid phase. Asymptotic analysis of the Boundary Condition confirms that it is of second order accuracy. The method is validated using (i) an analytical solution for the Nusselt number correlation of a single sphere in an unbounded stationary fluid and (ii) direct numerical simulations of the heat transfer between a fluid and individual particles.
James R Mathews - One of the best experts on this subject based on the ideXlab platform.
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the modified myers Boundary Condition for swirling flow
Journal of Fluid Mechanics, 2018Co-Authors: James R Mathews, Vianney Masson, Helene PossonAbstract:This paper gives a modified Myers Boundary Condition in swirling inviscid flow, which differs from the standard Myers Boundary Condition by assuming a small but non-zero Boundary layer thickness. The new Boundary Condition is derived and is shown to have the correct quadratic error behaviour with Boundary layer thickness and also to agree with previous results when the swirl is set to zero. The Boundary Condition is initially derived for swirling flow with constant azimuthal velocity, but easily extends to radially varying swirling flow, with terms depending on the Boundary layer model. The modified Myers Boundary Condition is then given in the time domain rather than in the frequency domain. The effect of the Boundary layer profile is then considered, and shown to be small compared to the Boundary layer thickness. The Boundary Condition is then used to analyse the eigenmodes and Green’s function in a realistic flow. Modelling the thickness of the Boundary layer properly is shown to be essential in order to get accurate results.
G R Hadley - One of the best experts on this subject based on the ideXlab platform.
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transparent Boundary Condition for the beam propagation method
IEEE Journal of Quantum Electronics, 1992Co-Authors: G R HadleyAbstract:A new Boundary Condition is presented for use in beam propagation calculations that passes outgoing radiation freely with minimum reflection coefficient (as low as 3*10/sup -8/). In conjunction with a standard Crank-Nicholson finite difference scheme, the assumption that the radiation field behaves as a complex exponential near the Boundary is shown to result in a specific transparent Boundary Condition algorithm. In contrast to the commonly used absorber method, this algorithm contains no adjustable parameters, and is thus problem independent. It is shown to be accurate and robust for both two- and three-dimensional problems. >
