The Mathematical Institute, University of Oxford, Eprints Archive

Implicit time accurate solutions on unstructured dynamic grids

Crumpton, P. I. and Giles, M. B. (1995) Implicit time accurate solutions on unstructured dynamic grids. Technical Report. Unspecified. (Submitted)



In this paper an unstructured multigrid algorithm is used as an iterative solution procedure for the discrete equations arising from an implicit time discretisation of the unsteady Euler equations on tetrahedral grids. To calculate unsteady flows due to oscillating boundaries, a novel grid movement algorithm is introduced, in which an elliptic equation with a nonlinear diffusion coefficient is used to define the displacement of interior grid nodes. This allows large grid displacements to be calculated in a single step. The multigrid technique uses a edge--collapsing algorithm to generate a sequence of grids, and a pseudo--timestepping smoother. On the coarser grids, no grid motion is used. Instead, surface normals are rotated consistently and transfer/interpolation weights are based on the time-averaged grid coordinates. A 2D NACA0012 test case is used to validate the program. 3D results are presented for the M6 wing and a full aircraft configuration.

Item Type:Technical Report (Technical Report)
Subjects:H - N > Numerical analysis
Research Groups:Numerical Analysis Group
ID Code:1338
Deposited By: Lotti Ekert
Deposited On:12 Jun 2011 08:52
Last Modified:29 May 2015 19:02

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