Authors: N. Ichikawa, T. Shigeta, K. Shirota
Addresses: Graduate School of Mathematics, Faculty of Science, Science University of Tokyo, Japan. ' Graduate School of Science and Engineering, Ibaraki University, Japan. ' Graduate School of Mathematics, Faculty of Science, Science University of Tokyo, Japan
Abstract: The purpose of this study is to present a new numerical treatment of the boundary conditions on the open boundary, which removes the non-physical reflection of the wave. In order to describe the motion of air in the earth|s atmosphere, a numerical solution of the averaged primitive flow equations is considered in this paper. Appropriate initial and boundary conditions should be imposed on the equations for the solution to be uniquely determined. Our particular interest is the boundary conditions on an open boundary where the flow comes in or out. It is known that conventional treatment of the boundary conditions causes non-physical reflection. To determine suitable boundary conditions for primitive equations, the theory of characteristics provides guidance on the number and form of the boundary conditions. We determined the boundary conditions by the theory of characteristics. The primitive equations are discretised using the second-order Taylor-Galerkin method with linear finite elements, and boundary values are computed by the method of characteristics. We consider simple numerical experiments of one- and two-dimensional problems. As a result, it is concluded that spurious oscillation is eliminated.
Keywords: compressible flow; non-isothermal viscous flow; fluid flow; finite element method; FEM; non-physical reflection; open boundary; primitive equations; Taylor-Galerkin method; modelling; horizontal flow; atmospheric flow; air flow.
International Journal of Computer Applications in Technology, 1998 Vol.11 No.3/4/5, pp.281 - 310
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