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A computational study of turbulent flow separation for a circular cylinder using skin friction boundary conditions
KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk analys, NA (stängd 2012-06-30).ORCID-id: 0000-0003-4256-0463
KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk analys, NA (stängd 2012-06-30).ORCID-id: 0000-0002-5020-1631
2011 (engelsk)Inngår i: Quality And Reliability Of Large-Eddy Simulations II, Springer Netherlands, 2011, Vol. 16, nr 1, s. 57-68Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

In this paper we present a computational study of turbulent flow separation for a circular cylinder at high Reynolds numbers. We use a stabilized finite element method together with skin friction boundary conditions, where we study flow separation with respect to the decrease of a friction parameter. In particular, we consider the case of zero friction corresponding to pure slip boundary conditions, for which we observe an inviscid separation mechanism of large scale streamwise vortices, identified in our earlier work. We compare our computational results to experiments for very high Reynolds numbers. In particular, we connect the pattern of streamwise vorticity in our computations to experimental findings of spanwise 3d cell structures reported in the literature.

sted, utgiver, år, opplag, sider
Springer Netherlands, 2011. Vol. 16, nr 1, s. 57-68
Serie
ERCOFTAC Series, ISSN 1382-4309 ; 16
Emneord [en]
turbulent boundary layer, flow separation, General Galerkin method, a posteriori error estimation, adaptive finite element method, skin firction boundary conditions
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-30280DOI: 10.1007/978-94-007-0231-8_5ISI: 000306194400005Scopus ID: 2-s2.0-84964887723ISBN: 978-94-007-0230-1 (tryckt)OAI: oai:DiVA.org:kth-30280DiVA, id: diva2:399296
Konferanse
2nd Workshop on Quality and Reliability of Large-Eddy Simulations, Univ Pisa, Pisa, Italy,Sep 09-11, 2009
Merknad

QC 20110224

Tilgjengelig fra: 2011-02-21 Laget: 2011-02-21 Sist oppdatert: 2013-12-13bibliografisk kontrollert
Inngår i avhandling
1. High performance adaptive finite element methods for turbulent fluid flow
Åpne denne publikasjonen i ny fane eller vindu >>High performance adaptive finite element methods for turbulent fluid flow
2011 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Understanding the mechanics of turbulent fluid flow is of key importance for industry and society as for example in aerodynamics and aero-acoustics. The massive computational cost for resolving all turbulent scales in a realistic problem makes direct numerical simulation of the underlying Navier-Stokes equations impossible. Recent advances in adaptive finite element methods offer a new powerful tool in Computational Fluid Dynamics (CFD). The computational cost for simulating turbulent flow can be minimized where the mesh is adaptively resolved, based on a posteriori error control. These adaptive methods have been implemented for efficient serial computations, but the extension to an efficient parallel solver is a challenging task.

This work concerns the development of an adaptive finite element method for modern parallel computer architectures. We present efficient data structures and data decomposition methods for distributed unstructured tetrahedral meshes. Our work also concerns an efficient parallellization of local mesh refinement methods such as recursive longest edge bisection.

We also address the load balance problem with the development of an a priori predictive dynamic load balancing method. Current results are encouraging with almost linear strong scaling to thousands of cores on several modern architectures.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2011. s. xii, 29
Serie
Trita-CSC-A, ISSN 1653-5723 ; 2011:02
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-30277 (URN)978-91-7415-878-6 (ISBN)
Presentation
2011-03-14, E3, KTH, Osquarsbacke 14, Stockholm, 10:15 (engelsk)
Opponent
Veileder
Merknad
QC 20110223Tilgjengelig fra: 2011-02-23 Laget: 2011-02-21 Sist oppdatert: 2011-02-23bibliografisk kontrollert
2. High Performance Adaptive Finite Element Methods: With Applications in Aerodynamics
Åpne denne publikasjonen i ny fane eller vindu >>High Performance Adaptive Finite Element Methods: With Applications in Aerodynamics
2013 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The massive computational cost for resolving all scales in a turbulent flow makes a direct numerical simulation of the underlying Navier-Stokes equations impossible in most engineering applications. Recent advances in adaptive finite element methods offer a new powerful tool in Computational Fluid Dynamics (CFD). The computational cost for simulating turbulent flow can be minimized by adaptively resolution of the mesh, based on a posteriori error estimation. Such adaptive methods have previously been implemented for efficient serial computations, but the extension to an efficient parallel solver is a challenging task. This work concerns the development of an adaptive finite element method that enables efficient computation of time resolved approximations of turbulent flow for complex geometries with a posteriori error control. We present efficient data structures and data decomposition methods for distributed unstructured tetrahedral meshes. Our work also concerns an efficient parallelization of local mesh refinement methods such as recursive longest edge bisection, and the development of an a priori predictive dynamic load balancing method, based on a weighted dual graph. We also address the challenges of emerging supercomputer architectures with the development of new hybrid parallel programming models, combining traditional message passing with lightweight one-sided communication. Our implementation has proven to be both general and efficient, scaling up to more than twelve thousands cores.

Abstract [sv]

Den höga beräkningskostnaden för att lösa upp alla turbulenta skalor för ett realistiskt problem gör en direkt numerisk simulering av Navier-Stokes ekvationer omöjlig. De senaste framstegen inom adaptiva finita element metoder ger ett nytt kraftfullt verktyg inom Computational Fluid Dynamics (CFD). Beräkningskostnaden för en simulering av turbulent flöde kan minimeras genom att beräkningsnätet adaptivt förfinas baserat på en a posteriori feluppskattning. Dessa adaptiva metoder har tidigare implementerats för seriella beräkningar, medan en effektiv parallellisering av metoden inte är trivial. I denna avhandling presenterar vi vår utveckling av en adaptiv finita element lösare, anpassad för att effektivt beräkna tidsupplösta approximationer i komplicerade geometrier med a posteriori felkontroll. Effektiva datastrukturer och metoder för ostrukturerade beräkningsnät av tetrahedrar presenteras. Avhandlingen behandlar även effektiv parallellisering av lokala nätförfiningsmetoder, exempelvis recursive longest edge bisection. Även lastbalanseringsproblematiken behandlas, där problemet lösts genom utvecklandet av en prediktiv dynamisk lastbalanseringsmetod, baserad på en viktad dualgraf av beräkningsnätet. Slutligen avhandlas även problematiken med att effektivt utnyttja nytillkomna superdatorarkitekturer, genom utvecklandet av en hybrid parallelliserings modell som kombinerar traditionell meddelande baserad parallellisering med envägskommunikation. Detta har resulterat i en generell samt effektiv implementation med god skalning upp till fler än tolv tusen processorkärnor.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2013. s. xii, 50
Serie
TRITA-CSC-A, ISSN 1653-5723 ; 2013:07
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-125742 (URN)978-91-7501-814-0 (ISBN)
Disputas
2013-09-11, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:15 (engelsk)
Opponent
Veileder
Merknad

QC 20130816

Tilgjengelig fra: 2013-08-16 Laget: 2013-08-13 Sist oppdatert: 2016-02-02bibliografisk kontrollert

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