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A fully discrete, stable and conservative summation-by-parts formulation for deforming interfaces
Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
Linköpings universitet, Matematiska institutionen, Beräkningsmatematik. Linköpings universitet, Tekniska fakulteten.
2016 (Engelska)Rapport (Övrigt vetenskapligt)
Abstract [en]

We introduce an interface/coupling procedure for hyperbolic problems posedon time-dependent curved multi-domains. First, we transform the problem from Cartesian to boundary-conforming curvilinear coordinates and apply the energy method to derive well-posed and conservative interface conditions.

Next, we discretize the problem in space and time by employing finite difference operators that satisfy a summation-by-parts rule. The interface condition is imposed weakly using a penalty formulation. We show how to formulate the penalty operators such that the coupling procedure is automatically adjusted to the movements and deformations of the interface, while both stability and conservation conditions are respected.

The developed techniques are illustrated by performing numerical experiments on the linearized Euler equations and the Maxwell equations. The results corroborate the stability and accuracy of the fully discrete approximations.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2016. , s. 38
Serie
LiTH-MAT-R, ISSN 0348-2960 ; 2016:9
Nyckelord [en]
Finite difference, High order accuracy, Deforming domains, Time-dependent interface, Well-posedness, Conservation, Summation-by-parts, Stability, Hyperbolic problems
Nationell ämneskategori
Beräkningsmatematik
Identifikatorer
URN: urn:nbn:se:liu:diva-130583ISRN: LiTH-MAT-R--2016/09--SEOAI: oai:DiVA.org:liu-130583DiVA, id: diva2:953284
Tillgänglig från: 2016-08-17 Skapad: 2016-08-17 Senast uppdaterad: 2017-04-27Bibliografiskt granskad
Ingår i avhandling
1. Stable High Order Finite Difference Methods for Wave Propagation and Flow Problems on Deforming Domains
Öppna denna publikation i ny flik eller fönster >>Stable High Order Finite Difference Methods for Wave Propagation and Flow Problems on Deforming Domains
2016 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

We construct stable, accurate and efficient numerical schemes for wave propagation and flow problems posed on spatial geometries that are moving, deforming, erroneously described or non-simply connected. The schemes are on Summation-by-Parts (SBP) form, combined with the Simultaneous Approximation Term (SAT) technique for imposing initial and boundary conditions. The main analytical tool is the energy method, by which well-posedness, stability and conservation are investigated. To handle the deforming domains, time-dependent coordinate transformations are used to map the problem to fixed geometries.

The discretization is performed in such a way that the Numerical Geometric Conservation Law (NGCL) is satisfied. Additionally, even though the schemes are constructed on fixed domains, time-dependent penalty formulations are necessary, due to the originally moving boundaries. We show how to satisfy the NGCL and present an automatic formulation for the penalty operators, such that the correct number of boundary conditions are imposed, when and where required.

For problems posed on erroneously described geometries, we investigate how the accuracy of the solution is affected. It is shown that the inaccurate geometry descriptions may lead to wrong wave speeds, a misplacement of the boundary condition, the wrong boundary operator or a mismatch of data. Next, the SBP-SAT technique is extended to time-dependent coupling procedures for deforming interfaces in hyperbolic problems. We prove conservation and stability and show how to formulate the penalty operators such that the coupling procedure is automatically adjusted to the variations of the interface location while the NGCL is preserved.

Moreover, dual consistent SBP-SAT schemes for the linearized incompressible Navier-Stokes equations posed on deforming domains are investigated. To simplify the derivations of the dual problem and incorporate the motions of the boundaries, the second order formulation is reduced to first order and the problem is transformed to a fixed domain. We prove energy stability and dual consistency. It is shown that the solution as well as the divergence of the solution converge with the design order of accuracy, and that functionals of the solution are superconverging.

Finally, initial boundary value problems posed on non-simply connected spatial domains are investigated. The new formulation increases the accuracy of the scheme by minimizing the use of multi-block couplings. In order to show stability, the spectrum of the semi-discrete SBP-SAT formulation is studied. We show that the eigenvalues have the correct sign, which implies stability, in combination with the SBP-SAT technique in time.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2016. s. 23
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1774
Nationell ämneskategori
Beräkningsmatematik Matematisk analys Strömningsmekanik och akustik
Identifikatorer
urn:nbn:se:liu:diva-130928 (URN)10.3384/diss.diva-130928 (DOI)9789176857373 (ISBN)
Disputation
2016-09-30, Visionen, Hus B, Campus Valla, Linköping, 13:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2016-08-31 Skapad: 2016-08-31 Senast uppdaterad: 2019-10-29Bibliografiskt granskad

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Version 1. Fully discrete, stable and conservative summation-by-parts formulation for deforming interfaces(1985 kB)160 nedladdningar
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Nikkar, SamiraNordström, Jan

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