The CFD Drag Prediction Workshop Series: Summary and ...dept.ku.edu/~cfdku/JRV/Levy.pdfThe CFD Drag Prediction Workshop Series: Summary and Retrospective Levy, et al DPW 5 Organizing

The CFD Drag Prediction Workshop Series: Summary and Retrospective

David W. Levy Cessna Aircraft Company

and the DPW Organizing Committee

Jameson, Roe, van Leer Symposium San Diego, CA 22-23 June 2013


The CFD Drag Prediction Workshop Series: Summary and Retrospective Levy, et al

DPW 5 Organizing Committee

David W. Levy and Kelly R. Laflin Cessna Aircraft Company

Edward N. Tinoco, John C. Vassberg, Mori Mani, and Ben Rider The Boeing Company: Seattle, Huntington Beach, and St. Louis

Christopher L. Rumsey, Richard A. Wahls, and Joseph H. Morrison NASA Langley Research Center

Olaf P. Brodersen and Simone Crippa DLR Institute of Aerodynamics and Flow Technology

Dimitri J. Mavriplis University of Wyoming

Mitsuhiro Murayama Japan Aerospace Exploration Agency

2



DPW Organizing Committee Past Members

Shreekant Agrawal The Boeing Company, Seattle

Steve Klausmeyer, Tom Zickuhr Cessna Aircraft Company

Mike Hemsch, Shahyar Pirzadeh NASA Langley Research Center

Bernhard Eisfeld, Mark Rakowitz DLR Institute of Aerodynamics and Flow Technology

Rick Matus Pointwise, Inc

Jean-Luc Godard ONERA

Bastiaan Oskam National Aerospace Laboratory

3



Outline of Presentation

• Introduction and Background

• Geometry Description

• Gridding Guidelines and Common Grids

• Participant and Test Case Descriptions

• Results and Discussion

• Conclusions

4



DPW Series Guidelines and Objectives • Assess state-of-the-art CFD methods as a practical tool. • Provide an impartial international forum. • Promote balanced participation across academia, government

labs, and industry. • Use common public-domain subject geometries. • Provide baseline grids to encourage participation and help reduce

variability. • Openly discuss areas needing added research and development. • Conduct rigorous statistical analyses of CFD results. • Schedule open-forum sessions to further engage interaction. • Maintain a public-domain accessible database of geometries,

grids, and results. • Document workshop findings in open literature.

5



DPW Workshop Series

Year Location Configuration Case Descriptions 2001 Anaheim, CA DLR-F4 Wing-Body Single Point Grid Refinement Study

Drag Polar Drag Rise Curves at Constant CL*

2003 Orlando, FL DLR-F6 Wing-Body Wing-Body-Nacelle

Single Point Grid Refinement Study Drag Polar Boundary Layer Trip Study* Drag Rise Curves at Constant CL*

2006 San Francisco, CA DLR-F6 Wing-Body with and without FX2B fairing; W1/W2 Wing Alone

Single Point Grid Refinement Study Drag Polar Grid Convergence Study Drag Polar

2009 San Antonio, TX NASA Common Research Model Wing-Body and Wing-Body-Tail

Grid Convergence Study Downwash Study Mach Sweep Study* Reynolds Number Study*

2012 New Orleans, LA NASA Common Research Model Wing-Body

Common Grid Study Buffet Study Turbulence Model Verification*

*Optional Cases

Note: All co-located with the AIAA Applied Aerodynamics Conference for that year

6



NASA Common Research Model

7

Horizontal tail and Nacelle available

• Developed by NASA Subsonic Fixed Wing Aero Technical Working Group with DPW Organizing Committee

• Modern transonic commercial transport airplane • Design Condition: M=0.85, CL=0.50, and REMAC=40x106 • Used in DPW 4 and 5



Gridding Guidelines (DPW 4-5)

1. Initial spacing normal to all viscous walls (RE Based on cref= 275.80”): a) coarse: y+ ~ 1.0 Dy1= 0.001478 (RE= 5M) b) medium: y+ ~ 2/3 Dy1= 0.000985 (RE= 5M), Dy1= 0.000273 (RE= 20M) c) fine: y+ ~ 4/9 Dy1= 0.000657 (RE= 5M) d) extra-fine: y+ ~ 8/27 Dy1= 0.000438 (RE= 5M)

2. Recommended: generate grids with 2 cell layers of constant spacing normal to viscous walls

3. Total grid size to grow ~3X between each grid level for grid convergence cases 4. For structured meshes, this growth is ~1.5X in each coordinate direction 5. Grid convergence cases must maintain the same grid family between grid levels,

i.e. maintain the same stretching factors, same topology, etc. 6. Growth rate of cell sizes in the viscous layer should be < 1.25. 7. Far field located at ~100cref for all grid levels. 8. For the Medium Baseline Grids:

a) Chordwise spacing for wing and tail leading edge (LE) and trailing edge (TE) ~0.1% local chord.

b) Wing and tail Spanwise spacing at root ~0.1% local semispan. c) Wing and tail Spanwise spacing at tip ~0.1% local semispan. d) Cell size near fuselage nose and after-body ~2.0% cref.

8



Multiblock Wing-Body Grid Family

• Finest grid (L6) developed first to extend into asymptotic range of grid convergence

• Coarsest grid (L1) multigrid capable to 3 levels

• Six grid size levels in total: L1-L6

10



Overset Grids

11

Overset Grid System: 3 Body Grids 2 Wing Grids (no wake) 4 Patch Grids (added)

• Main blocks same as MB grids

• Patch grids are point-matched



Unstructured Grids

• Use exact same cloud of points from MB/Overset families • Hex, prism, and hybrid tet/prism types • Each hex => 2 prisms; each prism => 3 tets • Negative volume issues • Sequences available for cell- or node-based schemes

12



Common Grid Family Metrics

13

Level Name Label D1 y+

Multiblock

Structured Overset

Unstr.

Hex

Unstr.

Prism Unstr. Hybrid

Cells Nodes Nodes Cells Cells Tets Prism Tot.

Cells

1 Tiny T 2.00 0.64 0.66 0.8 0.64 1.3 2.6 0.43 3.0

2 Coarse C 1.33 2.2 2.2 2.5 2.2 4.3 8.6 1.4 10.0

3 Medium M 1.00 5.1 5.2 5.7 5.1 10.2 20.8 3.3 24.1

4 Fine F 0.67 17.3 17.4 18.6 17.3 34.5 69.7 11.3 81.0

5 Extra Fine X 0.50 40.9 41.2 43.3 40.9 81.8 166.1 26.4 192.5

6 Super Fine S 0.33 138.0 138.8 143.5 138.0 --- --- --- ---

Note: All cell/node counts in millions



Participant Descriptions

• 57 Data Total Data Submittals • 22 Teams/Organizations

− 10 N. America, 5 Europe, 6 Asia, 1 S. America − 9 Government, 5 Industry, 6 Academia, 2 Commercial − 1 for Case 3 only

• Grid Types: − 5 Overset (4 Teams) − 7 Structured Multi-block ( 5 Teams) − 25 Unstructured (13 Teams: 14 Hex, 7 Hybrid, 4 Prism) − 20 Custom (7 Teams: 6 Overset, 2 MB, 2 Hex, 8 Hybrid, 2 Tet)

• Turbulence Models: − 38 SA (all types), 13 SST (all types), 4 Goldberg RT, 1 EARSM, 1 Lag-RST

14



Case 1 and 2 Participant Data Key

15

Team ID Name Organization Code Misc Solver Grid Type Turbulence Model

A Sclafani Boeing (Huntington) OVERFLOW v2.2c Central Overset SA-Ia

B Sclafani Boeing (Huntington) OVERFLOW v2.2c Central Overset SA-Ia w/ RC

C Sclafani Boeing (Huntington) OVERFLOW v2.2c Central Custom (Overset) SA-Ia

D Sclafani Boeing (Huntington) OVERFLOW v2.2c Central / QCR Custom (Overset) SA-Ia

E Sclafani Boeing (Huntington) OVERFLOW v2.2c Central Custom (Overset) SA-Ia w/ RC

F Sclafani Boeing (Huntington) OVERFLOW v2.2c Central / QCR Custom (Overset) SA-Ia w/ RC

G Sclafani Boeing (Huntington) OVERFLOW v2.2c Central Custom (Overset) SA-Ia w/ RC

H Sclafani Boeing (Huntington) OVERFLOW v2.2c Central / QCR Custom (Overset) SA-Ia w/ RC

I Chen CADRC MFlow Upwind Hex SA

J Chen CARDC MFlow Upwind Hybrid SA

K GariÈpy EcolePolytechMontreal Fluent V13 Upwind Prism SA

L GariÈpy EcolePolytechMontreal Fluent V13 Upwind Custom (Hex) SA

M Scalabrin Embraer CFD++ Upwind Hex RT

N Scalabrin Embraer CFD++ Upwind Hex SST

O Scalabrin Embraer CFD++ Upwind Hybrid RT

P Scalabrin Embraer CFD++ Upwind Hybrid SST

Q Scalabrin Embraer CFD++ Upwind Prism RT

R Scalabrin Embraer CFD++ Upwind Prism SST

S Scalabrin Embraer CFD++ Upwind Custom (Hybrid) RT

T Scalabrin Embraer CFD++ Upwind Custom (Hybrid) SST

U Eliasson FOI EDGE Central Hex EARSM

V Eliasson FOI EDGE Central Hex SA

W Eliasson FOI EDGE Central Hex SST

6 X Powell Gulfstream * FUN3D Upwind Roe Hybrid SA

7 Y Balakrishnan Indian Inst. Science HiFUN Upwind Hex SA

Z Hashimoto JAXA * FaSTAR Upwind Hex SA-noft2-R

2 Hashimoto JAXA FaSTAR Upwind Custom (Hex) SA-noft2-R

3 Yamamoto JAXA * UPACS Upwind Multi-block SA-noft2-R (Crot=1)

4 Yamamoto JAXA * UPACS Upwind Multi-block SST-V

5

8

9

1

2

3

4

* Data Resubmitted After Workshop ** Cases Added After Workshop



Case 1 and 2 Participant Data Key

16

Team ID Name Organization Code Misc Solver Grid Type Turbulence Model

10 5 Olson NASA Ames * overflow2.2e_LRS Central/matrix Overset Lag RST

6 Park NASA Langley FUN3D v12.2 Upwind Roe Hybrid SA

7 Park NASA Langley CFL3D v6.6 Upwind Roe Multi-block SA

12 8 Cai NPU China * ExStream Upwind Overset SST

13 9 Hue ONERA elsA Central Multi-block SA

14 a Coder Penn St. U OVERFLOW 2.2c Upwind Overset SA-fv3

b Osusky U. Toronto * Diablo Scalar Multi-block SA

d Osusky U. Toronto * Diablo Matrix Multi-block SA

e Levy Cessna Aircraft Co. * NSU3D Central/matrix Hybrid SA

f Levy Cessna Aircraft Co. FUN3D Upwind Roe Hybrid SA

g Crippa DLR TAU Matrix Hex SA

h Crippa DLR TAU Matrix Hex SST

18 k Moitra CRL_INDIA CFD++ Upwind Prism SA-RC

m Winkler Boeing (St. Louis) BCFD Upwind HLLE Hex SA

n Winkler Boeing (St. Louis) BCFD Upwind HLLE Hex SST-V

q Winkler Boeing (St. Louis) BCFD Upwind HLLE Hex SA

r Winkler Boeing (St. Louis) BCFD Upwind HLLE Hex SST-V

20 t Temmerman NUMECA FINE/Open Cell Centered Multi-block SA

a Brodersen DLR TAU Diss 1 Custom (Hybrid) SA

b Brodersen DLR TAU Diss 3 Custom (Hybrid) SA

d Brodersen DLR TAU Diss 1 Custom (Hyb w/Hex-Wake) SA

g Brodersen DLR TAU Diss 3 Custom (Hyb w/Hex-Wake) SA

l Brodersen DLR TAU Diss 1 Custom (Hyb w/Hex-Wake) Menter SST

p Brodersen DLR TAU Diss 3 Custom (Hyb w/Hex-Wake) Menter SST

x Powell Gulfstream ** FUN3D Upwind Roe Custom (Tet) SA

y Powell Gulfstream ** USM3D Upwind Roe Custom (Tet) SA

s Yamamoto JAXA ** UPACS Upwind Roe Custom (MB) SA-noft2-R (Crot=1)

v Yamamoto JAXA ** UPACS Upwind Roe Custom (MB) SST-V

17

19

21

6

9

11

15

16

* Data Resubmitted After Workshop ** Cases Added After Workshop



Case 1: Grid Convergence Study

17

• NASA Common Research Model, Wing-Body

• Mach=0.85, CL=0.500±0.001

• Grid Resolution Level: – 1) Tiny 2) Coarse 3) Medium,

– 4) Fine 5) Extra-Fine 6) Super-Fine

• Chord Reynolds Number: 5x106



Richardson Extrapolation: CD_TOT

18

Wind Tunnel Results shown for Reference Only

All Grids Common Grids Only Common Hex Grids Only

A

A

AA

A

B

B

BBBBB

EE

EEE

I

IIIII

J

JJ

JJ

K

KKK

K

LL

LLL

M

M

M

M

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O

O

O

O

P

P

PP

Q

Q

Q

Q

RRRR

S

S

S

S

T

T

T

T

U

UUUUUU

V

VVVVVVW

WWWWWW

X

XXXXX

Y

YY

YYY

Z

ZZ

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2

22

22

3

333333

4444444

5

5

5555

6

6

6666

7

77777

88888 9

999999

a

aa

aaaa

b

b

bbbbb

d

dddddd

e

e

ee

e

f

fffff gggggg hhhhhh

k

kk

kk

mm

mmm

n

nnnnn

q

qq

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r

rrrrr

t

tt

ttts

ssss

vvvvvvv

0.66M1M5M10M50M

100M

NTF

AMES

GRDFAC = 1/GRIDSIZE(2/3)

CD

_T

OT

0 5E-05 0.0001 0.000150.022

0.024

0.026

0.028

0.030

0.032

0.034OVERSETMULTI-BLOCKHYBRIDHEXPRISMCUSTOM

5 Counts

A

A

AA

A

B

B

BBBBB

I

IIIII

J

JJ

JJ

K

KKK

K

M

M

M

M

NNNN

O

O

O

O

P

P

PP

Q

Q

Q

Q

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U

UUUUUU

V

VVVVVVW

WWWWWW

X

XXXXX

Y

YY

YYY

Z

ZZ

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3

333333

4444444

5

5

5555

6

6

6666

7

77777

88888 9

999999

a

aa

aaaa

b

b

bbbbb

d

dddddd

e

e

ee

e

f

fffff gggggg hhhhhh

k

kk

kk

mm

mmm

n

nnnnn

q

qq

qqq

r

rrrrr

t

tt

ttt

0.66M1M5M10M50M

100M

NTF

AMES


CD

_T

OT

0 5E-05 0.0001 0.000150.022

0.024

0.026

0.028

0.030

0.032


5 Counts

A

A

AA

A

B

B

BBBBB

I

IIIII

M

M

M

M

NNNN

U

UUUUUU

V

VVVVVVW

WWWWWW

Y

YY

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Z

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3

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4444444

5

5

5555

7

77777

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999999

a

aa

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b

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d

dddddd gggggg hhhhhh

mm

mmm

n

nnnnn

q

qq

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r

rrrrr

t

tt

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0.66M1M5M10M50M

100M

NTF

AMES


CD

_T

OT

0 5E-05 0.0001 0.000150.022

0.024

0.026

0.028

0.030

0.032


5 Counts



Richardson Extrapolation: ALPHA and CM_TOT

19


AA

AA

A

BB

BBBBB

EE

EEE

I

IIIII

J

JJJJ

KKKK

K LLLLL

M

M

M

M

NNNN

O

O

O

O

PPPP

Q

Q

Q

Q

RRRR

S

SS

S

T

T

T

T

UUUUUUU

V

VV

VVVV

WWWWWWW

X

XX

XXX Y

YYYYY

Z

ZZZZZZ

222

22

3333333 4

44

4444 5

55555

6

66666

7

77

777

888889

999999

aaa

aaaa

b

bb

bbbb

d

dd

dddd

e

ee

ee

f

ff

fffgg

gggg

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k

kk

kkm

mmmm

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q

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r

rrrrrtttttt

sssss v

vv

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0.66M1M5M10M50M

100M

Ames

NTF


AL

PH

A

0 5E-05 0.0001 0.000151.8

2.0

2.2

2.4

2.6

2.8


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EEE

I

IIIII

J

JJJJ

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L

M

M

M

M

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44

4444

5

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77

777

88

888

99

99999

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f

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mmm

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sssss v

vv

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0.66M1M5M10M50M

100M

Ames

NTF


CM

_T

OT

0 5E-05 0.0001 0.00015-0.140

-0.130

-0.120

-0.110

-0.100

-0.090

-0.080

-0.070

-0.060

-0.050OVERSETMULTI-BLOCKHYBRIDHEXPRISMCUSTOM



Wind Tunnel Data

• Should we compare to Wind Tunnel Data? − Wind Tunnel and CFD measure/compute different things!

• Data are included for reference only

20

Wind Tunnel CFD

Walls Free Air

Support System (Sting) Free Air

Laminar/Turbulent (Tripped) “Fully” Turbulent (usually)

Aeroelastic Deformation Rigid 1g Shape

Measurement Uncertainty Numerical Uncertainty & Error

Corrections for known effects No Corrections

http://commonresearchmodel.larc.nasa.gov/

Rivers, M. and Dittberner, A., “Experimental Investigations of the NASA Common Research Model in the NASA Langley National Transonic Facility and NASA Ames 11-Ft Transonic Wind Tunnel (Invited),” AIAA Paper 2011-1126, presented at the 49th Aerospace Sciences Meeting, Orlando, FL, Jan 2011



Continuum Drag Extrapolation

21

0.0230

0.0235

0.0240

0.0245

0.0250

0.0255

0.0260

0.0265

0.0270

0.0275

0.0280

A B E I J K L M N O P Q R S T U V W X Y Z 2 3 4 5 6 7 8 9 a b d e r g h k m n q r t s v

CD

_TO

T

CFD Median= 0.02496CFD +/- StdDev= .00053NTF Test 197Ames Test 2165 Counts

0

5

10

15

20

0.0

24

2

0.0

24

4

0.0

24

6

0.0

24

8

0.0

25

0

0.0

25

2

0.0

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4

0.0

25

6

0.0

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8

0.0

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0

0.0

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2

0.0

26

4

0.0

26

6

0.0

26

8

0.0

27

0

0.0

27

2




Richardson Extrapolation Conclusions

22

• Most results are monotonically decreasing

• Some are nonlinear – Convergence issues – Flow-feature changes (SOB or TE Separation)

• Scatter is reduced somewhat for Common Grids – Scatter still large for coarser grids – Best for Hex-based, including Structured, Overset, and

Unstructured



Wing Pressures: Spanwise Trends

23

B

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E

E

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E

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E

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33

3

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344

4

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rr

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t

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t

t

ts

s

s

s

sv

v

v

v

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X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

L3 M=0.85 CL=.500 Station 4

OVRSETMLT-BLKHYBRIDHEXPRISMCUSTOM

B

B

B

B

BB

BB

BB

B

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E

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E

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J

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K

K

K

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K

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L

L

L

L

M

M

M

M

M

MN

N

N

N

N

NO

OO

O

O

O

O

O

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PP

P

P

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R

R

R

R

R

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S

S

S

S

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T

T

T

TU

U

U

U

U

UV

V

V

V

V

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W

W

W

W

WX

XX

X

X

X

X

X

X

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Y

Y

Y

Y

Y

Y

Z

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Z

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Z

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22

2

2

2

2

2

2

3

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

66

6

6

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6

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6

66

7

7

7

7 77

8

8

8

8

8

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9

a

a

a

a

a

a

b

b

b

b

b

bd

d

d

d

d

de

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h

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hk

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k

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k

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k

k

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m

m

m

m

m

m

n

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n

n

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q

q

q

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q

q

r

r

r

r

r

r

t

t

t

t tts

s

s

s

sv

v

v

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8



B

B

B

B

BB

B

B

BB

B

EE

E

EE

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E

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JK

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L

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O

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P

P

P

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R

R

R

R

R

R

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S

S

S

S

T

T

T

T

U

U

U

U

U

UV

V

V

V

V

VW

W

W

W

W

WX

XX

X

X

X

X

X

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z

2

2

2

2

2

223

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

66

6

6

6

6

6

6

667

7

7

7

77

8

8

8

8

8

8

99

9

9

9

9

a

a

a

a

a

ab

b

b

b

b

bd

d

d

d

d

de

ee

e

e

e

e

e

e

eef

ff

f

f

f

f

f

f

ffg

g

g

g

g

gh

h

h

h

h

hk

kk

k

k

k

k

k

k

kk

m

m

m

m

m

m

n

n

n

n

n

n

q

q

q

q

q

q

r

r

r

r

r

r

t

t

t

t

t

ts

s

s

s

sv

v

v

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8



B

B

B

B

BB

B

B

B

B

B

EE

E

E

E

E

E

E

E

E

EE

E

E

E

E

EEEE

E

I

I

I

I

I

I

J

JJ

J

J

J

J

J

J

JJK

KK

K

KK

K

K

K

KK

L

L

L

L

M

M

M

M

MM

N

N

N

N

N

N

O

O

O

OO

O

OO

OOO

P

P

P

PP

P

PP

P

PP

Q

Q

Q

QQ

Q

Q

Q

QQQ

R

R

R

RR

R

RR

R

RR

S

S

S S

T

T

TT

U

U

U

U

U

U

V

V

V

V

V

V

W

W

W

W

W

WX

X

X

XX

X

XX

X

XX

Y Y

Y

Y

Y

Y

Z

Z

Z

Z

Z

2

2

2

2

2

2

2

3

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

6

6

66

6

66

6

66

7

7

7

7

7

7

8

8

8

8

8

8

99

9

9

9

9

a

a

a

a

a

ab

b

b

b

b

bd

d

d

d

d

de

e

e

ee

e

ee

e

eef

f

f

ff

f

ff

f

ffg

g

g

g

g

gh

h

h

h

h

hk

k

k

kk

k

kk

k

kk

m

m

m

m

m

m

n

n

n

n

n

n

q

q

q

q

q

q

r

r

r

r

r

r

t

t

t

t

t

ts

s

s

s

sv

v

v

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

L3 M=0.85 CL=.500 Station 10


B

B

B

B

BB

B

B

B

B

BEE

E

EE

E

E

E

E

E

EE E

E

E

E

EEEE

E

I

I

I

I

I

I

JJ

J

J

J

J

J

J

J J

JKK

K

K

K

K

K

K

K

K

K

L

L

L

L

M

M

M

M

M

MN

N

N

N

N

NO

O

O

OO

O

O

O

O

OOP

P

P

PP

P

P

P

P

PPQ

Q

Q

QQ

Q

Q

Q

Q

QQR

R

R

RR

R

R

R

R

RRS

S

S

S

T

T

T

T

U

U

U

U

U

U

V

V

V

V

V

V

W

W

W

W

W

WX

X

X

XX

X

X

X

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z

2

2

2

2

2

3

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

6

6

66

6

6

6

6

667

7

7

7

7

7

8

8

8

8

8

8

9

99

9

9

9

a

a

a

a

a

a

b

b

b

b

b

bd

d

d

d

d

de

e

e

ee

e

e

e

e

eef

f

f

ff

f

f

f

f

ffg

g

g

g

g

gh

h

h

h

h

hk

k

k

kk

k

k

k

k

kk

m

m

m

m

m

m

n

n

n

n

n

n

q

q

q

q

q

q

r

r

r

r

r

r

t

t

t

t

t

t

s

s

s

s

sv

v

v

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

L3 M=0.85 CL=.500 Station 12


B

BB

B

BB

BB

B

B

B

EE

E

E

E

E

E

E

E

E E E

E E

E

E

EEEE

E

I

I

I

I

I

IJJ

J

J

J

J

J

J

J J

JK

KK

K

K

K

K K

K

KK

L

L

L

L

M

M

M

M

M

MN

N

N

N

N

NO

OO

OO

O

OO

O

OOP

PP

PP

P

PP

P

PPQ

QQ

QQ

Q

QQ

Q

QQR

RR

RR

R

RR

R

RRS

S

S

T

T

T

U

U

U

U

U

U

V

V

V

V

V

V

W

W

W

W

W

WX

XX

XX

X

XX

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z

2

2

2

23

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

66

66

6

66

6

667

7

7

7

7

7

8

88

8

8

8

9

9

9

9

9

9

a

a

a

a

a

ab

b

b

b

b

bd

d

d

d

d

de

ee

ee

e

e e

e

eef

ff

ff

f

ff

f

ffg

g

g

g

g

gh

h

h

h

h

hk

kk

kk

k

k

k

k

kk

m

m

m

m

m

m

n

n

n

n

n

n

q

q

q

q

q

q

r

r

r

r

r

r

t

t

t

t

tts

s

s

s

sv

v

v

v

v

X/CC

P

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

L3 M=0.85 CL=.500 Station 14


NTF Test 197 Run 44: a=2.66, CL=0.486 a=2.89, CL=0.520

=0.1306

=0.7268 =0.5024

=0.3971 =0.2828

=0.9500








Case 1 Discussion

24

• Still a lot of scatter! • No clear break-outs with grid type or turbulence model

– Some Turb. Models are outliers – Trends are still hard to isolate due to small sample sizes

• Agreement with experiment on CD_TOT is better than for ALPHA and CM_TOT – Wing aeroelastic effects are likely part of this – Spread in CD_TOT is similar for wind tunnel and CFD scatter

• Scatter is reduced somewhat for Common Grids – Statistics did not change significantly – Best for Hex-based, including Structured, Overset, and Unstructured – Discretization and Turbulence Modeling is still a major contributor

• Agreement in pressure data with experiment deteriorates at outboard stations, likely due to aeroelastic effects

• Variations in pressure data with grid level hard to discern due to reduced number of data sets



Case 2 Buffet Study:

25

• NASA Common Research Model, Wing-Body

• Mach=0.85: – α=2.50, 2.75, 3.00, 3.25, 3.50, 3.75, 4.00

• Grid Resolution Level: – 3) Medium (5.2M Nodes)

• Chord Reynolds Number: 5x106



CL_TOT and CM_TOT by Grid Type

26

Psuedo Test Data accounts for Aeroelastic Wing Twist

Some data show early lift break at low α



Wing SOB TE Separation Bubble

27

Some solutions had large SOB bubble which occurred for α=3.00 -3.50

Majority did not

Caused early lift break at low alpha

Streamlines shown are example from dataset “f” at α=3.50



CL_TOT and CM_TOT: Outliers Removed

28



Idealized Profile Drag

29

D

D

F

F

H

H

I

I

J

J

PU

U

V

V

W

W

2

2

5

5

7

7

9

9

e

e

h

h

k

k

m

m

q

q

r

r

t

t

lp

x

xy

y

0.015 0.016 0.017 0.018 0.019 0.020.5

0.52

0.54

0.56

0.58

0.6

SA-Ia Overset

SA-Ia Overset

SA-Ia Overset

SA HEX

SA HYBRID

SST HYBRID

EARSM HEX

SA HEX

SST HEX

SA-noft2-R HEX

LagRST

SA Strut MB

SA Strut MB

SA Strut MB

SA HYBRID

SST HEX

SA-RC PRISM

SA HEX

SST HEX

SA HEX

SST HEX

SA Strut MB

SST CUSTOM HEX

SST CUSTOM HEX

SA CUSTOM HEX

SA CUSTOM HEX

Ames Run 126

Ames Run 130

Ames Run 133

NTF Run 44

D

F

H

I

J

P

U

V

W

2

5

7

9

d

e

h

k

m

q

r

t

lpx

y

Case 2 - All Solutionsminus Outliers

10 Counts

NTF and Ames Test Data SA SST EARSM LagRST



Wing Pressures: Alpha Sweep

30

E

E

EE

E

E

E

EE

E

E

EE

E

F

F

FF

F

F

F

FF

F

F

FF

F

I

I

I

I

I

I

J

JJ

J

J

J

J J

J

JJ

L

L

L

L M

M

M

M

MM

N

N

N

N

N

N

O

O

O

OO

O

O

O

OOOP

P

P

PP

P

PP

P

PP

Q

Q

Q

QQ

Q

Q

Q

QQQ

R

R

R

RR

R

RR

R

RRS

S

S S

T

T

T T

U

U

U

U

U

U

V

V

V

V

V

V

W

W

W

W

W

WX

X

X

XX

X

X X

X

XX

YY

Y

Y

Y

Y

Z

Z

Z

Z

Z

2

2

2

2

2

2

2

3

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

6

6

66

6

6 6

6

6677

7

7

7

7

8

8

8

8

8

8

99

9

9

9

9

a

a

a

a

a

ab

b

b

b

b

be

e

e

ee

e

e e

e

eef

f

f

ff

f

f f

f

ffg

g

g

g

g

gh

h

h

h

h

hk

k

k

kk

k

k k

k

kk

m

m

m

m

m

m

n

n

n

n

n

n

q

q

q

q

q

q

r

r

r

r

r

r

tt

t

t

t

t

a

a

a a

a

a

a

a

a

a

a

a

b

b

b b

b

b

b

b

b

b

b

b

d

d

d d

d

d

d

d

dd

d

d

g

g

g g

g

g

g

g

gg

g

g

x

x

x

xx

x

x

x

x

xx

yy

yy

y

y

y

yy

y

y y

s

s

s

s

sv

v

v

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

L3 M=0.85 ALPHA=2.75 Station 10


EE

EE

E

E

E

EE

E

E

EE

E

FF

FF

F

F

F

FF

F

F

FF

F

II

I

I

I

I

J

J

J

J

J

J

J J

J

JJ

L

L

L

LM

M

M

M

MM

N

N

N

N

N

NO

O

O

OO

O

O

O

O

OOP

P

P

PP

P

P P

P

PP

Q

Q

Q

QQ

Q

Q

Q

QQQ

R

R

R

RR

R

R R

R

RRS

S

SS

T

T

T T

U

U

U

U

UU

V

V

V

V

V

V

W

W

W

W

W

WX

X

X

XX

X

X X

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z

2

2

2

2

2

2

2

3

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

6

6

66

6

6 6

6

6677

7

77

7

8

8

8

8

8

8

99

9

9

9

9

a

a

a

a

a

ab

b

b

b

b

be

e

e

ee

e

e e

e

eef

f

f

ff

f

f f

f

ffg

g

g

g

g

gh

h

h

h

h

hk

k

k

kk

k

k k

k

kk

m

m

m

m

m

m

n

n

n

n

n

n

q

q

q

q

q

q

r

r

r

r

r

r

tt

t

t

t

t

a

a

a a

a

a

a

a

a

a

a

a

b

b

b b

b

b

b

b

b

b

b

b

d

d

d d

d

d

d

d

d

d

d

d

g

g

g g

g

g

g

g

g

g

g

g

l

l

l l

l

l

l

l

l

l

l

l

p

p

p p

p

p

p

p

p

p

p

p

x

x

x

xx

x

x

x

x

xx

yy

yy

y

y

y

yy

y

y y

s

s

s

s

sv

v

v

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8



EE

EE

E

E

E

EE

E

E

EE

E

FF

FF

F

F

F

FF

F

F

FF

F

II

I

I

I

I

J

J

J

J

J

J

J J

J

JJ

L

L

L

L

M

M

M

M

MMN

N

N

N

N

NO

O

O

O

O

O

O

O

O

OOP

P

P

PP

P

P P

P

PP

Q

Q

Q

Q

Q

Q

Q

Q

QQQR

R

R

RR

R

RR

R

RRS

S

S

S

T

T

TT

U

U

U

U

U

U

V

V

V

V

VV

W

W

W

W

WW

X

X

X

XX

X

X X

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z

2

2

2

2

2

2

2

3

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

6

6

66

6

6 6

6

667

7

7 7 7

7

8

8

8

8

8

8

99

9

9

9

9

a

a

a

a

a

ab

b

b

b

b

be

e

e

ee

e

e e

e

ee

f

f

f

ff

f

f f

f

ff

g

g

g

g

g

gh

h

h

h

hhk

k

k

kk

k

k k

k

kk

m

m

m

m

m

m

n

n

n

n

n

n

q

q

q

q

q

q

r

r

r

r

r

r

tt

t

t

t

t

a

a

aa

a

a

a

a

aa

a

a

b

b

bb

b

b

b

b

bb

b

b

d

d

dd

d

d

d

d

dd

d

d

g

g

gg

g

g

g

g

gg

g

g

l

l

ll

l

l

l

l

l

l

l

l

p

p

pp

p

p

p

p

p

p

p

p

x

x

x

xx

x

x

x

x

xx

yy

yy

y

y

y

yy

y

y y

s

s

s

s

sv

v

v

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8



EE

EE

E

E

E

EE

E

E

EE

E

FF

FF

F

F

F

FF

F

F

FF

F

II

I

I

I

I

J

J

J

J

J

J

J J

J

JJ

L

L

L

L

M

M

M

M

MMN

N

N

N

N

NO

O

O

O

O

O

O

O

O

OOP

P

P

P

P

P

P P

P

PP

Q

Q

Q

Q

Q

Q

Q

Q

QQQR

R

R

R

R

R

R

R

R

RRS

S

S

S

T

T

T

T

U

U

U

U

U U

V

V

V

V

VV

W

W

W

W

WW

X

X

X

XX

X

X X

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z2

2

2

2

2

2

23

3

3

3

3

34

4

4

4

4

45

5

5

5

5

56

6

6

6

6

6

6 6

6

66

77

77

7

7

8

8

8

8

8

8

9

9

9

9

9

9

a

a

a

a

a

ab

b

b

b

b

b

e

e

e

e

e

e

e e

e

ee

f

f

f

ff

f

f f

f

ff

g

g

g

g

g

gh

h

h

h

hhk

k

k

k

k

k

k k

k

kk

m

m

m

m

m

m

n

nn

n

n

n

q

qq

q

q

q

r

rr

r

r

r

tt

t

t

t

t

a

a

aa

a

a

a

a

a

a

a

a

b

b

bb

b

b

b

b

b

b

b

b

d

d

dd

d

d

d

d

d

d

d

d

g

g

gg

g

g

g

g

g

g

g

g

l

l

ll

l

l

l

l

l

l

l

l

p

p

pp

p

p

p

p

p

p

p

p

x

x

x

xx

x

x

x

x

x xyy

yy

y

y

y

yy

y

y y

s

ss

s

sv

vv

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8



EE

EE

E

E

E

EE

E

E

EE

E

FF

FF

F

F

F

FF

F

F

FF

F

II

I

I

I

I

J

J

J

J

J

J

J

J

J

JJ

L

L

L

L

M

M

M

M

MMN

N

N

N

N

NO

O

O

O

O

O

O

O

O

OOP

P

P

P

P

P

PP

P

PP

Q

Q

Q

Q

Q

Q

Q

Q

QQQR

R

R

R

R

R

R

R

RRRS

S

S

S

T

T

T

T

U

U

U

U

U U

V

V

V

V

VV

W

W

W

W

WW

X

X

X

XX

X

X X

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z2

2

2

2

2

2

2 3

3

3

3

3

34

4

4

4

4

4

5

5

5

5

5

5

6

6

6

6

6

6

6 6

6

66

77

7

7

7

7

8

8

8

8

8

8

9

9

9

9

9

9

a

a

a

a

a

a

b

b

b

b

b

b

e

e

e

e

e

e

e e

e

ee

f

f

f

ff

f

f f

f

ff

g

g

g

g

g

gk

k

k

k

k

k

kk

k

kk

m

mm

m

m

m

n

nn

n

n

n

q

qq

q

q

q

r

rr

r

r

r

tt

t

t

t

t

a

a

aa

a

a

a

a

a

a

a

a

d

d

dd

d

d

d

d

d

d

d

d

g

g

gg

g

g

g

g

g

g

g

g

l

l

l

l

l

l

l

l

l

l

l

l

p

p

p

p

p

p

p

p

p

p

p

p

x

x

x

xx

x

x

x

x

x xyy

yy

y

y

y

y

y

y

y y

s

ss

s

sv

vv

v

v

X/C

CP

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8



EE

EE

E

E

E

EE

E

E

EE

E

FF

FF

F

F

F

FF

F

F

FF

F

II

I

II

I

J

J

J

J

J

J

J

J

J

JJ

M

M

M

M

MMN

N

N

N

N

NO

O

O

O

O

O

O

O

O

OOP

P

P

P

P

P

P

P

P

PP

Q

Q

Q

Q

Q

Q

Q

Q

QQQR

R

R

R

R

R

R

R

R

RRS

S

S

S

T

T

T

T

U

U

U

U

U U

V

V

V

V

VV

W

W

W

W

WW

X

X

X

X

X

X

X X

X

XX

Y

Y

Y

Y

Y

Y

Z

Z

Z

Z

Z2

2

2

2

2

2

23

3

3

3

3

34

4

4

4

4

45

5

5

5

55

6

6

6

6

6

6

6 6

6

66

77

7

7

7

7

8

8

8

8

8

8

9

9

9

9

9

9

a

a

a

a

a

a

b

b

b

b

b

b

e

e

e

e

e

e

e e

e

e

e

f

f

f

f

f

f

f f

f

ff

g

g

g

g

g

g

h

h

h

h

h hk

k

k

k

k

k

k

k

k

kk

m

mm

m

m

m

n

n n

n

n

n

q

q q

q

q

q

r

r r

r

r

r

tt

t

tt

t

a

a

a

a

a

a

a

a

a

a

a

a

b

b

bb

b

b

b

b

b

b

b

b

d

d

d

d

d

d

d

d

d

d

d

d

g

g

gg

g

g

g

g

g

g

g

g

l

l

l

l

l

l

l

l

l

l

l

l

x

x

x

xx

x

x

x

x

x x

yyy

y

y

y

y

y

y

y

yy

s

ss

s

sv

vv

v

v

X/CC

P

0 0.2 0.4 0.6 0.8 1

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8




= 0.5024

= 0.5024 =0.5024

= 0.5024 = 0.5024

= 0.5024








Case 2 Discussion

31

• No clear break-outs with grid type or turbulence model (except for some outliers – Goldberg RT )

• For all solutions minus outliers – Relatively tight forces and moment at a=2.5°, more spread at a=4.0°

• CL is too high and CM predicted too negative – Is it CFD, test, geometry, etc.?

• Steady aeroelastic effects are significant – Contributes to CL, CM errors, but not only factor

• High a data characterized by significant shock induced separation – Is the real flow steady at these conditions?

– Is RANS adequate or do we need URANS or DES?

• Large variation in shock location at high a



DPW Series Trend

32

0

20

40

60

80

100

120

140

160

180

200

DPW 1 DPW 2 DPW 3 DPW 4 DPW 5

Dra

g C

ou

nts

Data Spread

Std Dev

3M

23M

40M

189M138M

Yes, we are improving, but more needs to be done



General Conclusions

• Very successful workshop: Thanks to Participants • Still more variation than desired

– Some improvement from DPW-IV: We are getting better – Mixed results from common grid study

• Drag comparisons to wind tunnel generally favorable – Not clear that we should agree

• Force/Moment predictions better at low a – Less separation, but bigger spread at a=4.0°

• Pressures consistent with Force/Moments – Poorer correlation outboard points to aeroelastic effects

– Wide variation in a for shock separation

• Large variations in separation prediction – SOB Separation => Outliers

33



Further Study

• Check SOB/TE separation with wind tunnel data – Is flow visualization data available?

• Include static aeroelastics in CFD – Needed to match wind tunnel data

• Include boundary layer transition model – Forced/Free

• Unsteady RANS? – Will only help if flow is unsteady

• LES/DES? – DES only helps for off-body separation – LES (beyond current SOA?)

34

Documents

The CFD Drag Prediction Workshop Series: Summary and ...dept.ku.edu/~cfdku/JRV/Levy.pdfThe CFD Drag Prediction Workshop Series: Summary and Retrospective Levy, et al DPW 5 Organizing