| 1. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
- Changfoot, Donovan M., et al.
(författare)
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Hybrid Computational-Fluid-Dynamics Platform to Investigate Aircraft Trailing Vortices
- 2019
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Ingår i: Journal of Aircraft. - 0021-8669 .- 1533-3868. ; 56:1, s. 344-355
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Tidskriftsartikel (refereegranskat)abstract
- This paper outlines the development of a parallel three-dimensional hybrid finite volume finite difference capability. The specific application area under consideration is modeling the trailing vortices shed from the wings of aircraft under transonic flight conditions. For this purpose, the Elemental finite volume code is employed in the vicinity of the aircraft, whereas the ESSENSE finite difference software is employed to accurately resolve the trailing vortices. The former method is spatially formally second-order, and the latter is set to sixth-order accuracy. The coupling of the two methods is achieved in a stable manner through the use of summation-by-parts operators and weak imposition of boundary conditions using simultaneous approximation terms. The developed hybrid solver is successfully validated against an analytical test case. This is followed by demonstrating the ability to model the flowfield, including trailing vortex structures, around the NASA Common Research Model under transonic flow conditions. The interface treatment is shown to describe the intersecting vortices in a smooth manner. In addition, insights gained in resolving the vortices include violation of underlying assumptions of analytical vortex modeling methods.
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| 4. |
- Lundquist, Tomas, 1986-, et al.
(författare)
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A Method-of-Lines Framework for Energy Stable Arbitrary Lagrangian–Eulerian Methods
- 2023
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Ingår i: SIAM Journal on Numerical Analysis. - : Society for Industrial and Applied Mathematics. - 0036-1429 .- 1095-7170. ; 61:5, s. 2327-2351
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel framework based on semi-bounded spatial operators for analyzing and discretizing initial boundary value problems on moving and deforming domains. This development extends an existing framework for well-posed problems and energy stable discretizations from stationary domains to the general case, including arbitrary mesh motion. In particular, we show that an energy estimate derived in the physical coordinate system is equivalent to a semi-bounded property with respect to a stationary reference domain. The continuous analysis leading up to this result is based on a skew-symmetric splitting of the material time derivative and thus relies on the property of integration-by-parts. Following this, a mimetic energy stable arbitrary Lagrangian–Eulerian framework for semi-discretization is formulated, based on approximating the material time derivative in a way consistent with discrete summation-by-parts. Thanks to the semi-bounded property, a method-of-lines approach using standard explicit or implicit time integration schemes can be applied to march the system forward in time. The same type of stability arguments as for the corresponding stationary domain problem applies, without regard to additional properties such as discrete geometric conservation. As an additional bonus we demonstrate that discrete geometric conservation, in the sense of exact free-stream preservation, can still be achieved in an automatic way with the new framework. However, we stress that this is not necessary for stability.
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| 5. |
- Lundquist, Tomas, 1986-, et al.
(författare)
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Efficient and error minimized coupling procedures for unstructured and moving meshes
- 2020
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Ingår i: Journal of Computational Physics. - : Elsevier. - 0021-9991 .- 1090-2716. ; 406, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- We present a methodology for automatic generation and optimization of interpolation operators for the coupling of general non-collocated and/or moving numerical interfaces. The discrete equations are solved in a method-of-lines fashion by assuming volume preserving mesh motions. Interface interpolation errors are minimized effectively in a global least-squares sense, while satisfying strict stability conditions. The proposed automatic interface procedure is both more versatile and more accurate compared to previous techniques. We apply the new method to interfaces between hybrid meshes undergoing relative rigid body motion, demonstrating the stability, conservation and superior accuracy.
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| 6. |
- Nchupang, Mojalefa P., et al.
(författare)
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A provably stable and high-order accurate finite difference approximation for the incompressible boundary layer equations
- 2023
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Ingår i: Computers & Fluids. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0045-7930 .- 1879-0747. ; 267
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Tidskriftsartikel (refereegranskat)abstract
- In this article we develop a high order accurate method to solve the incompressible boundary layer equations in a provably stable manner. We first derive continuous energy estimates, and then proceed to the discrete setting. We formulate the discrete approximation using high-order finite difference methods on summation-by-parts form and implement the boundary conditions weakly using the simultaneous approximation term method. By applying the discrete energy method and imitating the continuous analysis, the discrete estimate that resembles the continuous counterpart is obtained proving stability. We also show that these newly derived boundary conditions removes the singularities associated with the null-space of the nonlinear discrete spatial operator. Numerical experiments that verifies the high-order accuracy of the scheme and coincides with the theoretical results are presented. The numerical results are compared with the well-known Blasius similarity solution as well as that resulting from the solution of the incompressible Navier–Stokes equations.
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