Dynamic unstructured method for flows past multiple objects in relative motion

Singh, K. P.; Newman, James C.; Baysal, Oktay

doi:10.2514/6.1994-58

Cited by 12 publications

(7 citation statements)

References 7 publications

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“…The spring analogy has been used by others [14][15] [16], with several choices for k. In this work, a constant value of k is sufficient to produce a good quality mesh. Also the advantage of this form of k is that one can use an implicit method for the right-hand side in Eqn.…”

Section: Mesh-moving Schemementioning

confidence: 99%

Direct Interface Tracking of Droplet Deformation

et al. 2002

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Direct interface tracking computes spray behavior based only on first principles. It is an advanced form of direct numerical simulation, but with the emphasis shifted from resolving details of turbulence to details of multiphase flow. The moving interface requires special treatment and advanced numerical methods. A code that is capable of accurate resolution of three-dimensional free-surface deformation has been constructed. The Navier-Stokes equations for the liquid phase are solved on a deforming unstructured mesh. This technique tracks the boundary precisely, similar to marker-and-cell methods. However the adaptive mesh deforms with the interface. Furthermore, this new method avoids the surface reconstruction required in volume of fluid methods. The numerical scheme produces a positive definite matrix that is solved using a conjugate gradient method. In order to maintain mesh quality, the mesh point connectivity and node locations are updated each time step. The results demonstrate the performance and accuracy of this technique. The method used for the surface tension force is 2 shown to be second-order accurate in space. By locally fitting the free surface to a parabola when evaluating curvature, problems with numerical noise in the solution are avoided. A time step criterion based on free surface numerical stability is discussed. The results for a deforming drop and collapsing ligament are presented. The code is validated by comparing to the theoretical period for drop deformation.

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Section: Mesh-moving Schemementioning

confidence: 99%

Direct Interface Tracking of Droplet Deformation

et al. 2002

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“…In the spring analogy approach each node can be considered as connected to its neighbours by springs, the stiffness of which is proportional to the reciprocal of the length [34,35]. This approach has been applied to optimization and unsteady flow problems but is expensive and can lead to grid quality problems for larger motions.…”

Section: Mesh Motionmentioning

confidence: 99%

Unified fluid–structure interpolation and mesh motion using radial basis functions

Rendall

Allen

2007

Numerical Meth Engineering

294

205

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SUMMARYA multivariate interpolation scheme, using radial basis functions, is presented, which results in a completely unified formulation for the fluid-structure interpolation and mesh motion problems. The method has several significant advantages. Primarily, all volume mesh, structural mesh, and flow-solver type dependence is removed, and all operations are performed on totally arbitrary point clouds of any form. Hence, all connectivity and user-input requirements are removed from the computational fluid dynamics-computational structural dynamics (CFD-CSD) coupling problem, as only point clouds are required to determine the coupling. Also, it may equally well be applied to structured and unstructured grids, or structural and aerodynamic grids that intersect, again because no connectivity information is required. Furthermore, no expensive computations are required during an unsteady simulation, just matrix-vector multiplications, since the required dependence relations are computed only once prior to any simulation and then remain constant. This property means that the method is both perfectly parallel, since only the data relevant to each structured block or unstructured partition are required to move those points, and totally independent from the flow solver. Hence, a completely generic 'black box' tool can be developed, which is ideal for use in an optimization approach. Aeroelastic behaviour of the Brite-Euram MDO wing is analysed in terms of both static deflection and dynamic responses, and it is demonstrated that responses are strongly dependent on the exact CFD-CSD interpolation used. Mesh quality is also examined during the motion resulting from a large surface deformation. Global grid quality is shown to be preserved well, with local grid orthogonality also being maintained well, particularly at and near the moving surface, where the original orthogonality is retained.

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“…(13 (Aftosmis et al, 1995;Alonso & Jameson, 1994;Ferziger & Peric, 1999;Frink, 1992;Singh et al, 1995;Trepanier et al, 1993).…”

Section: The Computational Fluid Dynamics Problemmentioning

confidence: 99%