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Implementation of free boundary condition at arbitrary sections using implicit conservative statements

Darbandi, M ; Sharif University of Technology | 2004

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  1. Type of Document: Article
  2. Publisher: 2004
  3. Abstract:
  4. The numerical solution of the fluid flow governing equations requires correct boundary condition implementations at suitable locations to produce well-posed problem. Most of numerical strategies exhibit weak performance and obtain inaccurate solutions if the boundary conditions are not placed at suitable locations. Unfortunately, many practical fluid flow problems such as those in oceanography pose difficulty at the boundaries because the required information for solving the PDE's is hardly available there. On the other hand, large solution domains with certain boundary conditions need huge number of mesh nodes. This can drastically increase the computer expenses. Such difficulties have motivated the CFD workers toward reducing the solution domain sizes and solving the problem with uncertain boundary conditions. In this work, we intend to develop a general strategy which enables the control-volume-based methods to close the outflow boundary at arbitrary locations where neither of fluid flow parameters is known. In this regard, we extend suitable conservative statements at the outflow boundary. The statements gradually detect the real conditions at those locations. Because of uncertain conditions at those locations, the statements are implicitly implemented. The current method is a collocated finite element volume. The extended formulation is then tested by solving the benchmark problem. The investigation shows that the downstream boundary can, if necessary, pass through a recirculation zone without adverse effect on solution accuracy. The results indicate that the formulation is robust enough to work if there are arbitrary boundary locations with uncertain boundary conditions around the solution domain
  5. Keywords:
  6. Artificial boundary ; Finite elementc ; Finite volume ; Implicit method ; Outflow boundary conditions
  7. Source: European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS 2004, Jyvaskyla, 24 July 2004 through 28 July 2004 ; 2004