Mixed Boundary-Element Formulation by the Method of Sub-Regions Applied to Three-Dimensional Convective Diffusion Problems

Yasuhiro TANAKA  Toshihisa HONMA  Ikuo KAJI  

IEICE TRANSACTIONS (1976-1990)   Vol.E69   No.3   pp.200-209
Publication Date: 1986/03/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: General

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We have presented a formulation of convective diffusion equations based on the method of sub-regions and the boundary element method, especially in three dimensions, in order to analyze very long and narrow convection-diffusion fields which we frequently encounter. In this formulation, we have introduced mixed-type boundary elements, which have more advantages in boundary element computation, and the weighted conservation law of mass in each sub-boundary model so as to be conservative in itself. In addition we have proposed a coupling technique at interface boundaries in order to equalize the number of equations to that of interface unknowns. As a result, it is found that the present method will give more accurate and stable solutions and also have more merits even on the basis of the method of sub-regions, and so is suitable and applicable particularly to a three-dimensional problem. The present formulation for mixed elements is also usable not only to convective diffusion problems, but also to Laplace and Helmholtz-type equations in steady and unsteady state.