8. Detached-‐eddy
simulaRon
(DES)
• P.
R.
Spalart
(1997):
– We
name
the
new
approach
“Detached-‐Eddy
Simula8on”
(DES)
to
emphasize
its
dis8nct
treatments
of
a?ached
and
separated
regions.
Super-‐Region
Region
Euler
(ER)
RANS
(RR)
Viscous
(VR)
Outer
(OR)
LES
(LR)
Viscous
(VR)
Focus
(FR)
Departure
(DR)
8
Spalart
(2001)
9. Detached-‐eddy
simulaRon
(DES)
• P.
R.
Spalart
(1997):
– We
name
the
new
approach
“Detached-‐Eddy
Simula8on”
(DES)
to
emphasize
its
dis8nct
treatments
of
a?ached
and
separated
regions.
Super-‐Region
Region
Euler
(ER)
RANS
(RR)
Viscous
(VR)
Outer
(OR)
LES
(LR)
Viscous
(VR)
Focus
(FR)
Departure
(DR)
Spalart
(2001)
9
12. OpenFOAMでの標準SGSモデル
Library
name
Note
Smagorinksy
Smagorinsky
model
Smagorinksy2
Smagorinsky
model
with
3-‐D
filter
homogeneousDynSmagor
insky
Homogeneous
dynamic
Smagorinsky
model
dynLagragian
Lagrangian
two
equaRon
eddy-‐viscosity
model
scaleSimilarity
Scale
similarity
model
mixedSmagorinsky
Mixed
Smagorinsky
/
scale
similarity
model
homogeneousDynOneEqE
ddy
One
EquaRon
Eddy
Viscosity
Model
for
incompressible
flows
laminar
Simply
returns
laminar
properRes
kOmegaSSTSAS
k-‐ω
SST
scale
adapRve
simulaRon
(SAS)
model
13. OpenFOAMでの標準SGSモデル
Library
name
Note
oneEqEddy
k-‐equaRon
eddy-‐viscosity
model
dynOneEqEddy
Dynamic
k-‐equaRon
eddy-‐viscosity
model
spectEddyVisc
Spectral
eddy
viscosity
model
LRDDiffStress
LRR
differenRal
stress
model
DeardorffDiffStress
Deardorff
differenRal
stress
model
SpalartAllmaras
Spalart-‐Allmaras
model
SpalartAllmarasDDES
Spalart-‐Allmaras
delayed
detached
eddy
simulaRon
(DDES)
model
SpalartAllmarasIDDES
Spalart-‐Allmaras
improved
DDES
(IDDES)
model
vanDriestDelta
Simple
cube-‐root
of
cell
volume
delta
used
in
incompressible
LES
models
18. OpenFOAMのテンソルクラス
演算
数学表記
クラス
加算
a
+
b
a
+
b
引算
a
–
b
a
–
b
スカラー乗算
sa
s
*
a
スカラー割り算
a
/
s
a
/
s
外積
a
b
a
*
b
内積
a
·∙
b
a
&
b
二重内積
a
:
b
a
&&
b
クロス積
a
×
b
a
^
b
平方
a2
sqr(a)
絶対値平方
|a|2
magSqr(a)
絶対値
|a|
mag(a)
べき乗
an
pow(a,
n)
19. OpenFOAM
tensor
classes
Opera2on
Mathema2cal
Class
転置
TT
T.T()
対角
diag
T
diag(T)
トレース
tr
T
tr(T)
偏差成分
dev
T
dev(T)
対称成分
symm
T
symm(T)
非対称成分
skew
T
skew(T)
行列式
det
T
det(T)
余因子
cof
T
cof(T)
逆行列
inv
T
inv(T)
25. WALEモデルのパラメータ
Field
a
Field
b
Field
c
Field
d
Field
e
Field
f
Cw
2/Cs
2
10.81
10.52
10.84
10.55
10.70
11.27
If CS = 0.18, 0.55 ≤ CW ≤ 0.6.
If CS = 0.1, 0.32 ≤ CW ≤ 0.34.
モデルパラメータCwは
Smagorinsky定数CSに依存
するので,流れ場によって変更する必要がある.
(Nicoud
and
Ducros,
1999)
32. Reτ
=
110
でのチャネル流れの計算
$ ./Allrun
7. その他の解析条件やパラメータを確認後,ソルバーを実行
する.
8. If
the
solver
calculaRon
is
normally
finished,
you
check
the
logs
and
visualize
the
flow
field
with
ParaView.
If
the
integraRon
Rme
is
not
sufficient
for
the
flow
field
to
become
fully
developed
state,
run
longer
simulaRons.
49. References
• OpenFOAM
User
Guide
• OpenFOAM
Programmer’s
Guide
• 梶島,
乱流の数値シミュレーション 改訂版,
養賢堂
(2014).
• P.
R.
Spalart
et
al.,
“Comments
on
the
Feasibility
of
LES
for
Wings,
and
on
a
Hybrid
RANS/LES
Approach”,
1st
ASOSR
CONFERENCE
on
DNS/LES
(1997).
• P.
R.
Spalart,
“Young-‐Person’s
Guide
to
Detached-‐Eddy
SimulaRon
Grids”,
NASA
CR-‐2001-‐211032
(2001).
• F.
Nicoud
and
F.
Ducros,
“Subgrid-‐scale
modelling
based
on
the
square
of
velocity
gradient
tensor”,
Flow,
Turbulence
and
CombusRon,
62,
pp.183-‐200
(1999).
50. References
• 小林,
“乱流構造に基づくサブグリッドスケールモデルの開
発”,
ながれ,
29,
pp.157-‐160
(2010).
• H.
Kobayashi,
“The
subgrid-‐scale
models
based
on
coherent
structures
for
rotaRng
homogeneous
turbulence
and
turbulent
channel
flow”,
Phys.
Fluids,
17,
045104
(2005).
• H.
Kobayashi,
F.
Ham
and
X.
Wu,
“ApplicaRon
of
a
local
SGS
model
based
on
coherent
structures
to
complex
geometries”,
Int.
J.
Heat
Fluid
Flow,
29,
pp.640-‐653
(2008).