Multigrid Approach in two consecutive Obstacles Fluid

• Main Authors: S, C.H., 石佳弘
• Other Authors: Lan C.W.
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/25353686482144138570

碩士 === 國立中興大學 === 土木工程學系 === 86 === The Multigrid method combining with the automatic, adaptive mesh refinement technique is used to simulate the behaviors of two- dimensional unstaedy ,incompressible ,viscous laminar flow .The governing equations of continuity and momentum are transformed into stream-continuity and vorticity transport equation.The multigrid approach requires a data structure that is simple enough to imple- mentefficiently,yet flexible enough to premit the very complicated patterns of local mesh refinement that would be generated by an adaptive mesh refinement strategy .The adaptive mesh refinement criterion is based on estimates of the first order derivative error .The finite differences method is applied in the models.ADI(Alternating Direction Implicition) method and SOR(Successive Over-Relaxa-tion) method are applied in solving the continuity equatuion and vorticity equation separately.The model is verified with an analytical solution of potencial flow,firstly.Then it is applied to simulating one or two consecutive obstacles fluid,and discussthe positions of reattch point after the obstacles.In this paper,we discuss the change of reattch point with three difference Reynold number,and change the distance of obstacles to discuss the change of fluid in difference situations.The model of multigrid approach combined with automatic adaptive refinement technique can produce an efficient and stable solution strategy for solving the steady-state and unsteady-steady incompressible Navier- Stokes equations.Considerable memory savings as well as a reduction in the total CPU time are achieved. To use the local refinementof mesh to detect the locations where sharp velocity gradient exists.