Progress in Simulations of Turbulent Boundary Layers Philipp - - PowerPoint PPT Presentation

▶
progress in simulations of turbulent boundary layers
SMART_READER_LITE
LIVE PREVIEW

Progress in Simulations of Turbulent Boundary Layers Philipp - - PowerPoint PPT Presentation

Jan 23, 2024 33 likes •673 views

Progress in Simulations of Turbulent Boundary Layers Philipp Schlatter Ramis rl, Qiang Li, Geert Brethouwer, Henrik Alfredsson, Arne Johansson, Dan Henningson Linn FLOW Centre, KTH Mechanics, Stockholm, Sweden TSFP-7, Ottawa, July 31,

slide-1
SLIDE 1

Progress in Simulations of Turbulent Boundary Layers

Philipp Schlatter Ramis Örlü, Qiang Li, Geert Brethouwer, Henrik Alfredsson, Arne Johansson, Dan Henningson Linné FLOW Centre, KTH Mechanics, Stockholm, Sweden TSFP-7, Ottawa, July 31, 2011

slide-2
SLIDE 2

2

TSFP7, July 31, 2011

Philipp Schlatter

Outline: Turbulent Boundary Layers

  • Comparison of DNS

– Re-evaluation of data

  • New KTH simulations and experiments

– Something about codes – Establishment of fully-developed turbulence – Detailed comparison to experiments

  • Some findings and detours

– Wall shear stress, negative velocities and high flatness – Modulation of near-wall turbulence – Three-dimensional effects – Suction boundary layer – Coherent structures (Eduction, Visualisations) – Passive scalars and free-stream turbulence – Sublayer scaling, finding the wall and correcting hotwires – Ongoing new simulation

  • Conclusions
slide-3
SLIDE 3

3

TSFP7, July 31, 2011

Philipp Schlatter

Outline: Turbulent Boundary Layers

  • Comparison of DNS

– Re-evaluation of data

  • New KTH simulations and experiments

– Something about codes – Establishment of fully-developed turbulence – Detailed comparison to experiments

  • Some findings and detours

– Wall shear stress, negative velocities and high flatness – Modulation of near-wall turbulence – Three-dimensional effects – Suction boundary layer – Coherent structures (Eduction, Visualisations) – Passive scalars and free-stream turbulence – Sublayer scaling, finding the wall and correcting hotwires – Ongoing new simulation

  • Conclusions
slide-4
SLIDE 4

18

TSFP7, July 31, 2011

Philipp Schlatter

Turbulence close to the surface  Friction  Drag  Fuel consumption

Turbulent flow close to solid walls...

slide-5
SLIDE 5

19

TSFP7, July 31, 2011

Philipp Schlatter large and small scales: multi-scale phenomena!

Turbulent flow close to solid walls...

(simulation result)

slide-6
SLIDE 6

20

TSFP7, July 31, 2011

Philipp Schlatter large and small scales: multi-scale phenomena!

Turbulent flow close to solid walls...

(simulation result) Recent reviews: Marusic et al., Phys. Fluids, 2010 Klewicki, J. Fluids Eng., 2010 Smits et al., Annu. Rev. Fluid Mech., 2011

slide-7
SLIDE 7

25

TSFP7, July 31, 2011

Philipp Schlatter

DNS of Turbulent Boundary Layers (TBL)

slide-8
SLIDE 8

26

TSFP7, July 31, 2011

Philipp Schlatter

What we are used/expect to see …

Fernholz & Finley (1996) Monkewitz et al. (2008)

Physical experiments are commonly scrutinised before they are employed to calibrate, test, or validate

  • ther experiments, scaling laws or theories

Compilation/ Assessment of experimental data from ZPG TBL flows DNS DNS

slide-9
SLIDE 9

27

TSFP7, July 31, 2011

Philipp Schlatter

… and what “we” are not so used to see

Simulation data are hardly scrutinised, when it comes to basic (integral) quantities

Schlatter & Örlü (2010) Red symbols are data from 7 independent DNS from ZPG TBL flows DNS DNS

slide-10
SLIDE 10

29

TSFP7, July 31, 2011

Philipp Schlatter

Employed ZPG TBL DNS data

Wu & Moin (2010) 900 – 1840 * Ref.: Schlatter & Örlü, J. Fluid Mech. 2010 Lee & Sung (2011) 2560 finite differences, recycling

slide-11
SLIDE 11

30

TSFP7, July 31, 2011

Philipp Schlatter

Justification for re-evalution

  • Integral quantities are often given as function of Re, however,

how these were computed is often not given in detail

  • Varying free-stream velocities for y+ > d+ implies (in

conjunction with quite varying box height) unambiguous upper integral bound and free-stream velocity  Need for consistent re-evaluation!

slide-12
SLIDE 12

31

TSFP7, July 31, 2011

Philipp Schlatter

Consistent way to re-evaluate

  • For the following re-evaluation we make use of the

Nickels (2004) composite profile to determine free-stream velocity and the 99% boundary-layer thickness

  • Chauhan, Monkewitz & Nagib (2009) composite profile for near-

wall comparisons

  • 4th order polynomial fit around maxima of Reynolds stresses to

determine peak value and location

slide-13
SLIDE 13

34

TSFP7, July 31, 2011

Philipp Schlatter

Re H12

300 1000 3000 1.4 1.5 1.6 1.7

Re cf  103

300 1000 3000 3 4 5 6

A closer look at DNS from ZPG TBL flows

Shape factor & Skin friction

Data from 8 independent DNS (Schlatter & Örlü, JFM, 2010)

  • “we” are usually very confident about DNS data, at least when it

comes to basic integral quantities, but …

Chauhan et al. (2009) ± 1 %, 5 % Smits et al. (1983) ± 5 %, 20 %

slide-14
SLIDE 14

42

TSFP7, July 31, 2011

Philipp Schlatter

  • “we” are usually very confident

about DNS data, when it comes to mean velocity profiles, but …

  • Note of caution: profiles have

been utilised in the past to develop corrections for total- head probes, wall position, friction velocity, etc…

(see Örlü et al., JPAS, 2010)

Chauhan et al. (2009)

A closer look...

Inner layer

Re cf  103

300 1000 3000 3 4 5 6

slide-15
SLIDE 15

46

TSFP7, July 31, 2011

Philipp Schlatter

Need for new simulations close to experiments…

slide-16
SLIDE 16

55

TSFP7, July 31, 2011

Philipp Schlatter

Spatial Boundary Layer

computational domain (periodic) physical domain fringe region laminar turbulent transitional

U1

x0

trip forcing

  • Fully spectral method: Fourier/Chebyshev tau method
  • Periodic boundary condition in the wall-parallel directions,

no-slip at lower wall, Neumann conditions at upper boundary.

  • Fringe region (volume force) to enforce laminar Blasius inflow
  • Trip forcing to induce “natural” laminar-turbulent transition
  • Code SIMSON (Chevalier et al. 2007) on up to 16384 cores BG/P

± ±0

slide-17
SLIDE 17

73

TSFP7, July 31, 2011

Philipp Schlatter

TBL up to Re = 4300...

real aspect ratio aspect ratio 4:1 : Re=180 Re=4000 Re=2500 Re=1410 Re=3500 Re=1000 Skote (2001) Schlatter et al. (2009) Wu & Moin (2010) Jiménez et al. (2010) Ferrante & Elghobashi (2004) Schlatter & Örlü (JFM 2010)

tripping to turbulence, Re=180

x+=9, y+=0.04-14, z+=4 Total: 7.5¢109 grid points

slide-18
SLIDE 18

74

TSFP7, July 31, 2011

Philipp Schlatter

TBL up to Re = 4300...

Re=180 Re=4000 Re=2500 Re=1410 Re=3500 Re=1000 Skote (2001) Schlatter et al. (2009) Wu & Moin (2010) Jiménez et al. (2010) Ferrante & Elghobashi (2004) DeGraaff & Eaton Erm & Joubert DeGraaff & Eaton Örlü Österlund Örlü Österlund EXP: Osaka Osaka Örlü Österlund Purtell Purtell x+=9, y+=0.04-14, z+=4 Total: 7.5¢109 grid points

slide-19
SLIDE 19

78

TSFP7, July 31, 2011

Philipp Schlatter

Some quick statistics…

slide-20
SLIDE 20

79

TSFP7, July 31, 2011

Philipp Schlatter

Integral Quantities up to Re=4300

  • Skin friction cf and shape factor H12

Medium DNS Fine DNS High DNS DNS Spalart (1988) Re=300, 670, 1410 DNS Jiménez et al. (2009) Re=1100, 1550, 2000 EXP Österlund (1999) Re=2500, 3000 ... EXP Örlü (2008) Re=2500, 3000 ... Correlations (Monkewitz et al. 2007, Österlund (1999)) DNS Skote (2001)

Re H12

1000 2000 3000 4000 1.3 1.4 1.5 1.6

Re cf

1000 2000 3000 4000 5000 2 3 4 5 6 7 x 10

  • 3
slide-21
SLIDE 21

82

TSFP7, July 31, 2011

Philipp Schlatter

DNS – Comparison to EXP

y+ U+

10 10

1

10

2

10

3

5 10 15 20 25

y+ U+

10

2

10

3

16 18 20 22 24 26 Comparison to experiments by Örlü (2008) at Re=2532, 3640, 4080 and Österlund (1999) at Re=2532, 3060, 3651 present DNS at matching Re Re=4080 Re=2532

slide-22
SLIDE 22

96

TSFP7, July 31, 2011

Philipp Schlatter

Re (u/U )2 = (1/2) cf

1000 2000 3000 4000 1 2 3 4 x 10

  • 3

Von Kármán Integral Equation

  • von Kármán equation
  • Derived based on boundary-layer approximation
  • Terms balance up to O(0.1%)

u2

¿ = U2 1

dµ dx + d dx Z 1 ¡ hu02i ¡ hv02i ¢ dy

slide-23
SLIDE 23

101

TSFP7, July 31, 2011

Philipp Schlatter

However, how about lower Reynolds numbers?

slide-24
SLIDE 24

103

TSFP7, July 31, 2011

Philipp Schlatter

Evolution from initial conditions

  • Spatial development  turbulence needs to be

continuously generated close to / at the inflow: – artifical turbulence (e.g. Klein et al.) – precursor (periodic) simulation – recycling/rescaling (Lund et al.) – tripping/transition to turbulence

  • Immediate questions:

– Depending on method, what inflow length is necessary? – Pressure gradient during adaptation/transition? – what is the lowest Re for ”fully developed” turbulence Similar issues in experiments, see e.g. Erm & Joubert (1991), Castillo et al. (2004)

?

Ref.: Örlü & Schlatter, ETC-13, 2011

slide-25
SLIDE 25

106

TSFP7, July 31, 2011

Philipp Schlatter

Different Trippings

  • Visualisation:

negative 2 (Jeong & Hussain 1995) region Rex=70,000- 750,000 (half of the computational domain)

Re=1100 Re=1250 Re=1600 Re=1700

Ref.: Örlü & Schlatter, ETC-13, 2011

slide-26
SLIDE 26

108

TSFP7, July 31, 2011

Philipp Schlatter

Inflow Length: Tripping

  • We consider 4 different tripping mechanisms:

a) baseline b) low amplitude c) low frequency d) Tollmien-Schlichting (TS) waves All simulations reach a common friction curve at some Re. Skin friction cf is a measure for inner-layer convergence...? turbulent laminar

cf

Re=1100

slide-27
SLIDE 27

116

TSFP7, July 31, 2011

Philipp Schlatter

Inflow Length: Tripping

  • Contours of u+

rms (steps 0.25)

a) baseline b) low amplitude c) low frequency d) Tollmien-Schlichting (TS) waves

slide-28
SLIDE 28

117

TSFP7, July 31, 2011

Philipp Schlatter

Inflow Length: Tripping

  • Contours of u+

rms (steps 0.25)

a) baseline b) low amplitude c) low frequency d) Tollmien-Schlichting (TS) waves

slide-29
SLIDE 29

118

TSFP7, July 31, 2011

Philipp Schlatter

Inflow Length: Tripping

  • Contours of u+

rms (steps 0.25)

a) baseline b) low amplitude c) low frequency d) Tollmien-Schlichting (TS) waves

slide-30
SLIDE 30

119

TSFP7, July 31, 2011

Philipp Schlatter

Inflow Length: Tripping

  • Contours of u+

rms (steps 0.25)

a) baseline b) low amplitude c) low frequency d) Tollmien-Schlichting (TS) waves

slide-31
SLIDE 31

120

TSFP7, July 31, 2011

Philipp Schlatter

Inflow Length: Tripping

  • Contours of u+

rms (steps 0.25)

a) baseline b) low amplitude c) low frequency d) Tollmien-Schlichting (TS) waves tripping at higher Re

slide-32
SLIDE 32

122

TSFP7, July 31, 2011

Philipp Schlatter

Inflow Length: Tripping

  • Consider three Re=1100, 1550, 2000

y+ U+

10 10

1

10

2

10

3

5 10 15 20 25

y+

10

2

10

3

18 20 22 24

baseline TS-waves Jiménez et al. (2010)

Re=1100 Re=2000 Re=1550

Ref.: Örlü & Schlatter, ETC-13, 2011

slide-33
SLIDE 33

125

TSFP7, July 31, 2011

Philipp Schlatter

Let’s compare DNS and experiments…

slide-34
SLIDE 34

126

TSFP7, July 31, 2011

Philipp Schlatter

  • ZPG TBL flow in the range 2300< Reθ <7500 (Örlü, 2009)
  • single hot-wire measurements at 1.65m from leading edge
  • f a 7m long plate fulfilling “equilibrium” criteria (à la

Chauhan et al. 2009)

  • independent skin friction measurements by means of
  • il-film interferometry
  • DNS corresponds to a 2m stretch…

Thesis Örlü 2009

MTL wind tunnel

0.8m x 1.2m

New experiments at KTH

25m 10m

slide-35
SLIDE 35

129

TSFP7, July 31, 2011

Philipp Schlatter

  • - - Correlation by Chauhan et al. (2009)

± 1 %, 5 % ± 5 %, 20 %

Shape factor & skin friction coefficient

Recall

Örlü and Schlatter, iTi 2010

slide-36
SLIDE 36

130

TSFP7, July 31, 2011

Philipp Schlatter

Shape factor & skin friction coefficient

In the following slides data from DNS at and experiments at will be shown and data at will be compared

Örlü and Schlatter, iTi 2010

slide-37
SLIDE 37

131

TSFP7, July 31, 2011

Philipp Schlatter

Mean streamwise velocity profiles

DNS (solid lines) EXP (symbols)

Log-law indicator function Mean velocity profile Örlü and Schlatter, iTi 2010

slide-38
SLIDE 38

132

TSFP7, July 31, 2011

Philipp Schlatter

Turbulence intensity profiles

(e.g. Örlü & Alfredsson, EF, 2010)

  • -- DNS with matched spatial

resolution to hot-wire length

slide-39
SLIDE 39

138

TSFP7, July 31, 2011

Philipp Schlatter

Pre-multiplied spectral map

DNS EXP

Örlü and Schlatter, iTi 2010

slide-40
SLIDE 40

139

TSFP7, July 31, 2011

Philipp Schlatter

Pre-multiplied spectral map

DNS EXP

Örlü and Schlatter, iTi 2010

slide-41
SLIDE 41

146

TSFP7, July 31, 2011

Philipp Schlatter

Wall-shear stress w

slide-42
SLIDE 42

149

TSFP7, July 31, 2011

Philipp Schlatter

Wall-shear stress fluctuation

Wall shear stress: Fluctuation: Main reference: Alfredsson et al. (1988): Explanation with spatial resolution... Channel flows Skote (2001) Ferrante & Elghobashi (2005) Correlation Österlund ( ) Schlatter & Örlu (2010) Jiménez et al. (2010) Wu & Moin, Phys. Fluids 2010 * * * * * * * * * * * * * DNS EXP Ref.: Örlü & Schlatter, Phys. Fluids, 2011

slide-43
SLIDE 43

152

TSFP7, July 31, 2011

Philipp Schlatter

Wall-shear stress fluctuation

120+ 0.9d99 Re

Power spectrum of   Inner part essentially invariant (viscous scaling)  Outer peak scales in outer units and is increasing 2D spectrum of w

  • Why increasing for all Re, even for low Re?

120+ 1000+/Uc Ref.: Örlü & Schlatter, Phys. Fluids, 2011

slide-44
SLIDE 44

160

TSFP7, July 31, 2011

Philipp Schlatter

Spatial Structures…

slide-45
SLIDE 45

179

TSFP7, July 31, 2011

Philipp Schlatter

visualised domain: length 7000+ 5.0 d99 width 4500+ 3.2 d99

Disturbance Velocity

  • positive and negative streamwise

disturbance velocity ( 0.1U1) at Re=4000 view from top view from bottom d99 R d99 2z+ = 115 2z/d99 = 0.85 d99

slide-46
SLIDE 46

180

TSFP7, July 31, 2011

Philipp Schlatter

Amplitude Modulation

  • Cross-stream cut through the boundary layer
  • currugated edge of the boundary layer
  • clear modulation of the whole boundary layer

(including near-wall region) vortical structures, coloured by streamwise velocity low-speed high speed z

slide-47
SLIDE 47

194

TSFP7, July 31, 2011

Philipp Schlatter

  • Example

Reµ=1000 Reµ=1410 Reµ=2500 Reµ=4000

Amplitude Modulation

Remove symmetric part: Refs.: Mathis et al. (2009); Bernardini & Pirozzoli, Phys. Fluids 2011

slide-48
SLIDE 48

195

TSFP7, July 31, 2011

Philipp Schlatter

  • Example

Reµ=1000 Reµ=1410 Reµ=2500 Reµ=4000

Amplitude Modulation

Re maximum Cmod

1000 2000 3000 4000 0.1 0.2 0.3 0.4

Increase of modulation coefficient in agreement with the findings by Bernardini & Pirozzoli 2011. +

slide-49
SLIDE 49

261

TSFP7, July 31, 2011

Philipp Schlatter

Structures – Visualisation

slide-50
SLIDE 50

293

TSFP7, July 31, 2011

Philipp Schlatter

”Focus on Fluids” (May 2009)...

Figures: Wu & Moin (JFM 2009)

slide-51
SLIDE 51

301

TSFP7, July 31, 2011

Philipp Schlatter

Boundary Layer Visualisation

based on LES data

slide-52
SLIDE 52

302

TSFP7, July 31, 2011

Philipp Schlatter

Boundary Layer Visualisation

based on DNS data

slide-53
SLIDE 53

309

TSFP7, July 31, 2011

Philipp Schlatter

Structures...

Isocontours of negative 2 and positive / negative disturbance velocity

slide-54
SLIDE 54

310

TSFP7, July 31, 2011

Philipp Schlatter

Structures...

slide-55
SLIDE 55

311

TSFP7, July 31, 2011

Philipp Schlatter

Structures...

Isocontours of 2, colour code ~ wall distance

slide-56
SLIDE 56

314

TSFP7, July 31, 2011

Philipp Schlatter

Structures...

Isocontours of 2, colour code ~ wall distance

slide-57
SLIDE 57

368

TSFP7, July 31, 2011

Philipp Schlatter

Preliminary Results: Ongoing simulation up to Reµ=8300

slide-58
SLIDE 58

369

TSFP7, July 31, 2011

Philipp Schlatter

LES up to Reµ=8300

  • Ongoing LES (using ADM-RT)

Re cf

2000 4000 6000 8000 2 3 4 5 6 x 10

  • 3

y+ U+

10 10

1

10

2

10

3

10

4

5 10 15 20 25 30

Domain: 13500 x 400 x 540d0*

Re Re = 500-8300 ; Re Re¿ = 2300

Resolution: 9216 x 513 x 768 (8.5 billion grid points) x+=18, y+=0.06-16, z+=8 Friction coefficient Mean velocity

new LES DNS 4300 Örlü (2009)

Reµ=1000 Reµ=2500 Reµ=4000 Reµ=5800 Reµ=7500

EXP Örlü (2009)

slide-59
SLIDE 59

370

TSFP7, July 31, 2011

Philipp Schlatter

LES up to Reµ=8300

  • Ongoing LES (using ADM-RT)

Re cf

2000 4000 6000 8000 2 3 4 5 6 x 10

  • 3

y+ U+

10 10

1

10

2

10

3

10

4

5 10 15 20 25 30

Domain: 13500 x 400 x 540d0*

Re Re = 500-8300 ; Re Re¿ = 2300

Resolution: 9216 x 513 x 768 (8.5 billion grid points) x+=18, y+=0.06-16, z+=8 Friction coefficient Mean velocity

Reµ=1000 Reµ=2500 Reµ=4000 Reµ=5800 Reµ=7500

new LES DNS 4300 Örlü (2009)

y+ U+

10

2

10

3

18 20 22 24 26 28

Reµ=7500 Reµ=2500 Reµ=1000

EXP Örlü (2009) EXP Örlü (2009)

slide-60
SLIDE 60

371

TSFP7, July 31, 2011

Philipp Schlatter

LES up to Reµ=8300

  • Ongoing LES (using ADM-RT)

y+ 

10 10

1

10

2

10

3

1 2 3 4 5 6

y+ urms

+

10 10

1

10

2

10

3

10

4

0.5 1 1.5 2 2.5 3

Reµ=1000 Reµ=2500 Reµ=4000 Reµ=5800 Reµ=7500

¥ = y+(dhUi+=dy+)

Reynolds stresses Indicator function

  • Good agreement at lower Reynolds

number with other DNS/LES

  • Good agreement with experiments at

higher Re

  • Proper scaling behaviour at higher Re

Re Re = 500-8300 ; Re Re¿ = 2300

Correlation Monkewitz et al.

slide-61
SLIDE 61

373

TSFP7, July 31, 2011

Philipp Schlatter

Conclusions

DNS data for a spatial turbulent zero pressure gradient turbulent boundary layer from Re=180 up to Re=4300, using ~7.5·109 grid points. NUMERICAL EXPERIMENT

  • 1. Statistics/budgets/spectra/PDF etc. in excellent

agreement with experiments

  • 2. Outer-layer convergence and fully developed state for

boundary layers. When do we have a ”good” simulation?

  • 3. Large-scale structures O(d99) with footprint/modulation

visible at the wall

  • 4. Visualisation of coherent structures in high-Re turbulent

boundary layers: No clear hairpin vortices detected except for low-Re (transition) region. Data and visualisations at: www.mech.kth.se/~pschlatt/DATA Contact me: pschlatt@mech.kth.se

slide-62
SLIDE 62

374

TSFP7, July 31, 2011

Philipp Schlatter Swedish National Infrastructure for Computing

Acknowledgments:

slide-63
SLIDE 63

375

TSFP7, July 31, 2011

Philipp Schlatter

Thank You!

slide-64
SLIDE 64

376

TSFP7, July 31, 2011

Philipp Schlatter

Boundary Layer Visualisation

based on DNS data