An intergrid-boundary definition method for overset unstructured grid approach

Nakahashi, K.

doi:10.2514/6.1999-3304

Cited by 19 publications

(11 citation statements)

References 13 publications

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“…1,2 Relatively recent activities have applied the approach to unstructured grids to accommodate relative motion and to eliminate the need to regrid for geometry changes. 3,4 There is significant interest in adding an overset capability to other flow solvers.…”

Section: Introductionmentioning

confidence: 99%

DiRTlib: A Library to Add an Overset Capability to Your Flow Solver

Noack

2005

17th AIAA Computational Fluid Dynamics Conference

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The modifications to a flow solver to add an overset capability can be an impediment to developers wishing such a capability. The Donor interpolation Receptor Transaction library (DiRTlib) is a solver neutral library that simplifies the addition of an overset capability to a flow solver by encapsulating the required operations. This paper discusses the design issues of such a general capability and details the use of DiRTlib in a solver.

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Section: Introductionmentioning

confidence: 99%

DiRTlib: A Library to Add an Overset Capability to Your Flow Solver

Noack

2005

17th AIAA Computational Fluid Dynamics Conference

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“…Note that the trip terms have been omitted from the above equation for application to fully turbulent flows (for example, see the works of Allmaras et al 49 and Rumsey 50 ). The sensitivity of the right-hand side of Equation (13) with respect to the wall distance function, which is required for the evaluation of the error assessment ratio (12), is derived in the Appendix. Both of the fast wall distance computation algorithm described in Section 2 and the error estimation controlled approach presented in Section 3 are implemented in the massively parallel flow solver AERO-F. All structural computations reported in this section are performed using AERO Suite's massively parallel nonlinear structural analyzer AERO-S, and all FSI computations reported herein for the simulation of PID are performed using AERO Suite's explicit-explicit partitioned analysis procedure presented in the work of Farhat et al 51…”

Section: Computational Frameworkmentioning

confidence: 99%

Fast computation of the wall distance in unsteady Eulerian fluid‐structure computations

Grimberg

Farhat

2018

Numerical Methods in Fluids

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Summary Highly nonlinear, turbulent, dynamic, fluid‐structure interaction problems characterized by large structural displacements and deformations, as well as self‐contact and topological changes, are encountered in many applications. For such problems, the Eulerian computational framework, which is often equipped with an embedded (or immersed) boundary method for computational fluid dynamics, is often the most appropriate framework. In many circumstances, it requires the computation of the time‐dependent distance from each active mesh vertex of the embedding mesh to the nearest embedded discrete surface. Such circumstances include, for example, modeling turbulence using the Spalart‐Allmaras or detached eddy simulation turbulence models and performing adaptive mesh refinement in order to track the boundary layer. Evaluating at each time step the distance to the wall is computationally prohibitive, particularly in the context of explicit‐explicit fluid‐structure time‐integration schemes. Hence, this paper presents two complementary approaches for reducing this computational cost. The first one recognizes that many quantities depending on the wall distance are relatively insensitive to its inaccurate evaluation in the far field. Therefore, it simplifies a state‐of‐the‐art algorithm for computing the wall distance accordingly. The second approach relies on an effective wall distance error estimator to update the evaluation of the wall distance function only when otherwise, a quantity of interest that depends on it would become tainted by an unacceptable level of error. The potential of combining both approaches for dramatically accelerating the computation of the wall distance is demonstrated with the Eulerian simulation of the inflation of a disk‐gap‐band parachute system in a supersonic airstream.

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“…One thing that has to be taken into consideration is that the grids in a higher layer are usually finer than those grids in a lower layer for the sake of resolving the flow structure in the near-field region; hence, they are expected to be retained for the computation. In the present study, the overset grid uses the wall distance [28] to define the activity of the points and thus provides the appropriate resolution to the local situation. The minimum self-wall distances from each grid node to the wall boundaries in its own cluster are first measured.…”

Section: Hierarchical Overset Grid Systemmentioning

confidence: 99%

“…In addition to the grid regeneration and mesh deformation methodologies, the overset grid is a mature technology that has been used for over 30 years to simplify the grid generation for complex geometries and as an embedding technique for simulations involving multiple bodies with relative movement. The overset grid scheme was firstly proposed by Benek et al [27] and subsequently extended by Nakahashi et al [28] for applications on unstructured grids. By hole-cutting and interpolation in overlapping mesh regions, the grid intersection can in principle be avoided.…”

Section: Introductionmentioning

confidence: 99%

A dynamic mesh strategy applied to the simulation of flapping wings

Deng

Xiao

Oudheusden

et al. 2016

Numerical Meth Engineering

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SUMMARYA robust and efficient dynamic grid strategy based on an overset grid coupled with mesh deformation technique is proposed for simulating unsteady flow of flapping wings undergoing large geometrical displacement. The dynamic grid method was implemented using a hierarchical unstructured overset grid locally coupled with a fast radial basis function (RBF)-based mapping approach. The hierarchically organized overset grid allows transferring the grid resolution for multiple blocks and overlapping/embedding the meshes. The RBF-based mapping approach is particularly highlighted in this paper in view of its considerable computational efficiency compared with conventional RBF evaluation. The performance of the proposed dynamic mesh strategy is demonstrated by three typical unsteady cases, including a rotating rectangular block in a fixed domain, a relative movement between self-propelled fishes and the X-wing type flapping-wing micro air vehicle DelFly, which displays the clap-and-fling wing-interaction phenomenon on both sides of the fuselage. Results show that the proposed method can be applied to the simulation of flapping wings with satisfactory efficiency and robustness.

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An intergrid-boundary definition method for overset unstructured grid approach

Cited by 19 publications

References 13 publications

DiRTlib: A Library to Add an Overset Capability to Your Flow Solver

DiRTlib: A Library to Add an Overset Capability to Your Flow Solver

Fast computation of the wall distance in unsteady Eulerian fluid‐structure computations

A dynamic mesh strategy applied to the simulation of flapping wings

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