Inhalt – Numerische Stro127 omungsmechanik I

Turbulenzmodelle in der Strömungsmechanik: RANS & LES
Turbulence modelling: RANS & LES (VNr. 6221913)
WS 2015/16
Prof. Dr. Markus Uhlmann
Stand 29. September 2015
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Zeit und Ort/Time and location
Zeit:
Kursbeginn:
Ort:
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Mittwochs 11:30–13 Uhr
21.10.2015
HS 93, Gebäude 10.81
Wednesday 11:30–13 h
21.10.2015
HS 93, Bldg. 10.81
Kontakt/Contact
Sprechstunden:
Ort:
Telefon:
Email:
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Time:
Start:
Location:
nach Vereinbarung
Raum 122, Geb. 10.81
0721-608 47245 (Sekretariat)
[email protected]
Consultation:
Location:
Phone:
by appointment
Room 122, Bldg. 10.81
0721-608 47245
Ziele der Vorlesung/Aim and scope of the course
• Einführung in die Problematik der Berechnung turbulenter Strömungen/ Introduction to
computational approaches for turbulent flows
• Detaillierte Beschreibung der gängigen statistischen Turbulenzmodelle (basierend auf ReynoldsMittelung)/ Discussion of the RANS approach
• Einführung in die Grobstruktursimulation/ Introduction to LES
• Detaillierte Beschreibung der Feinstrukturmodelle für LES/ Discussion of subgrid-scale models for LES
• Diskussion der Leistungsfähigkeit und Grenzen besprochener Modelle/ Discussion of applicability and limitations of RANS and LES models
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Vorlesungs- und Übungsmaterialien, Skript/Supporting material
Werden unter ILIAS zur Verfügung gestellt. Bitte treten Sie dort diesem Kurs bei. Die URL ist wie
folgt:
https://ilias.studium.kit.edu/goto produktiv crs 414447.html
Please register under the above indicated URL.
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Notwendige Vorkenntnisse/Prerequisites
• Grundkenntnisse in Strömungsmechanik/Basic fluid mechanics
• Grundkenntnisse in Mathematik (partielle DGLs, Statistik, Fourieranalyse) /
Mathematics (PDEs, statistics, Fourier analysis)
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• Englischkenntnisse
• Besuch der Veranstaltung “Fluidmechanik turbulenter Strömungen”/ having passed the course “Fluid mechanics of turbulent flows” (VNr. 6221806)
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Prüfung/Exam
Der Leistungsnachweis besteht aus einer 30 minütigen mündlichen Prüfung. Der Termin der
Prüfung wird noch bekanntgegeben. Anmeldung bis spätestens letzte Vorlesungswoche. / Oral
exam, 30 minutes, date to be announced.
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Zeitliche Planung, Inhalt der Vorlesung/Planning
KW
43
44
45
46
47
48
49
50
51
2
3
4
5
6
Nr.
V1
V2
V3
V4
V5
V6
V7
V8
V9
V10
V11
V12
V13
Thema
General information
Introduction
DNS – an overview
Introduction to RANS
Eddy viscosity models
Reynolds stress transport models
Boundary conditions
Algebraic stress models
(buffer date)
Introduction to LES
LES equations
Subgrid-scale modelling
Wall models for LES
(buffer date)
DNS–LES–RANS
(DNS)
(RANS)
(RANS)
(RANS)
(RANS)
(RANS)
(RANS)
(LES)
(LES)
(LES)
(LES)
(LES)
Datum
21.10.
28.10.
4.11.
11.11.
18.11
25.11.
2.12.
9.12.
16.12.
13.1.2016
20.1.2016
27.1.2016
3.2.2016
10.2.2016
General information:
Presentation of the general aims of this course, course attendance
V1: General introduction to the computation of turbulent flows
Introduction to modelling and simulation, approaches of DNS, LES and RANS – criteria for
appraising turbulence models
V2: Direct numerical simulation (DNS) as a numerical experiment
Computational requirements for DNS – examples of simulations in idealized geometries – homogeneous flows – inhomogeneous flows – scaling
V3: Introduction to Reynolds-averaged Navier-Stokes (RANS) models
General approach – classification of models/hierarchy – eddy viscosity approach – algebraic models
– one- and two-equation models
V4: k-ε and other eddy viscosity models
Description – model assumptions – model equation for the dissipation rate – determining the
model constants – variants of the basic model
V5: Transport models for the Reynolds stress
Disadvantages of the eddy viscosity approach – advantages of transport models for the Reynolds
stress – closure assumptions for the transport equations – modelling the pressure/rate-of-strain
term – examples
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V6: Boundary conditions and wall treatment
Basic approaches for imposing boundary conditions in RANS – problems associated with modelling
the near-wall region – wall function approach – extension of RANS models to low-Reynolds number
zones
V7: Algebraic stress models
Disadvantages of Reynolds stress transport models – derivation of algebraic models – non-linear
eddy-viscosity models
V8: (buffer date for RANS)
V9: Introduction to Large Eddy Simulation (LES)
Basic principles – filtering – decomposition of the velocity field
V10: LES equations
Derivation of the filtered Navier-Stokes equations – closure problem
V11: Subgrid-scale modelling I
Models in the RANS tradition – eddy viscosity models: Smagorinsky model, dynamic procedure
– other models: scale-similarity approach, deconvolution models, implicit LES
V12: Wall models for LES
Problems when describing the wall region with LES – wall models – hybrid approaches (LESRANS)
V13: (buffer date for LES)
Literatur/References
[1] S.B. Pope. Turbulent flows. Cambridge University Press, 2000.
[2] P.A. Durbin and P.A. Petterson Reif. Statistical theory and modeling for turbulent flows. Wiley,
2001.
[3] D.C. Wilcox. Turbulence Modeling for CFD. DCW Industries, second edition, 1998.
[4] J. Fröhlich. Large Eddy Simulation turbulenter Strömungen. Teubner, 2006.
[5] W. Rodi, G. Constantinescu, and T. Stoesser. Large-Eddy Simulation in Hydraulics. IAHR
Monographs. CRC Press, 2013.
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