Progress Through Quality Education
P. R. Naren
School of Chemical & Biotechnology
SASTRA Deemed to be University
Thanjavur 613401
E-mail: [email protected]at
One Week
National Workshop on Advances in Computational Mechanics
School of Mechanical Engineering
SASTRA Deemed to be University
Thanjavur 613401
Finite Volume Method
14-Dec-2018
Finite volume method
Outline
- Conservation equations and control volume
- – Eulerian and Lagrangian framework
- – Integral form of conservation equation
- FVM approach
- – Steady state diffusion equation in 1D
- – Convective term
- Issues with collocated grid
15-Dec-18
Governing Equations
- Conservation of mass
Transport Equations Conservation of momentum • Conservation of energy •
Concept of CV • m
lim
- Finite volume method 15-Dec-18
Framework
- Lagrangian
- Eulerian
- – Fixed reference
- – Moving reference
- Finite control volume
- Infinitesimally small
control volume
Samimy et al., 2003
- – Integral form
- – Gross behaviour
- – Differential form
- – No discontinuity
Finite volume method
15-Dec-18
Advection
V V
N i
N i
T T P P u
u u Balance Unit Mass Unit Volume
m 1
N
m u A i
N N i i
x u
T
T T
P m u P
u C T P
P P
Q mC T
P x i
N i
Q C T P
N i
C x i i
Finite volume method 15-Dec-18 Generic Transport Equation Transport equation for a quantity f •
f
f f div( V ) div grad S f
t Accumulation + Net outflow = Net Diffusion + Net source
Equation Specific quantity f S f per unit mass)
Mass balance
1 m Momentum u g
P balance
- D
Energy balance C T k H UADT
p R
Species balance i x D r i i
Finite volume method 15-Dec-18 Mass Balance
- Mass
d i v ( ) U
t u v w
t x y zFinite volume method 15-Dec-18 Momentum Balance Navier Stokes •
D U div p div S
M
Dt u
p
- m div( u ) div grad u S U
Mx t x Stokes
Navier Finite volume method 15-Dec-18
Taylor
Numerical Techniques
- Finite Difference • Finite Element • Finite Volume
Finite volume method
15-Dec-18
Geometry
Finite volume method
15-Dec-18
Finite volume method
15-Dec-18
Illustration: 1D heat Conduction
Steady state 1D heat conduction in a solid rod with ends kept at fixed temp
Model Formulation
- Axisymmetric
- – q
- – L >> D – Radial variation ignored
- – No heat loss thro’ surrounding
- Governing equation
- BC: z = 0 T = T
A
; z = L T = T
B
with constant thermo-physical properties
Finite volume method T
A
T B L
T
A
T B d d T d z d z axisymmetric
1D approx’on
15-Dec-18
- Analytical Solution
- – Continuous
-
B A A
-
2 T T i 2 to N 1 T T T T
T
1 A N B
i 1 i i 1
T T T T z L
Grids Soln
- Numerical solution
- – Finite Difference – Solution at discrete points
- – Affected by Dz
T B Finite Diff
T B
T
A
T BT
AFinite volume method
T
A
Solution to Heat Conduction in Rod
-
15-Dec-18
Typical Temperature Profile
Finite volume method
15-Dec-18
Issues with Finite Difference Solution discrete vs. governing equation continuous • Treatment of local source terms • Discontinuities in solution • Nature of conservation laws •
Finite volume method 15-Dec-18 Integral Form of Conservation Equation
x
f
Integrating over CV
Finite volume method For steady state flow For 1D flow
f
D f
x x x x d d d u S. d x S. d x S S.d x d x d x d x f D D
Gaub
x d d d
u d d S d
d x d x d x f D D D f S dx d dx d u dx d
f f S grad div u div
f
S grad div u div
t f f f
f
f
f
f
15-Dec-18
Integral Form of Momentum Equation
u uu vu p u u
- m m t x y x x x y y
Integrating over CV
u uu vu p u u
m m dt dv dV dV dV dV -
t x y x x x y y
D D D D D D t
V V
V V V For steady state flow
uu vu p u u
m m dv dV dV dV dV-
x y x x x y y
D
V D
V D
V D
V D V Finite volume method 15-Dec-18 FVM Approach for Heat Conduction Computational domain for • heat conduction in rod
Temperature at node is – L average of CV around the
T B
T
A node- – Boundary nodes
Internal nodes – T
T
A
BFinite volume method 15-Dec-18 Finite Volume Formulation f
f f div u div grad S f
t N
f f div u div grad S f n f d d d w P e E
W f
u S f x dx dx dx s S f d d d
f u dV dV S f dV x
dx dx dx
D D D
V V
V
15-Dec-18
19
Some Mathematics !!
- Taylor Series
2 h
' ''
f x h f x hf x f x ...
2 !
2 h
' ''
-
f x h f x hf x f x ...
2 !
3
2 h
' "' 2 h ''
- - f x h f x h 2 hf x 2 f x ...
- f x h f x h 2 f x f x ...
3 ! 2 !
3 - - f x h f x h
1 h "'
- ' f x h 2 f x f x h
- ''
f x f x ...
- f x ...
- 2
2 h h 3 ! h
Finite volume method 15-Dec-18
w e
2 u u
S N Finite Volume Formulation . . .
S dV dV dx d dx d dV u dx d
V x
V V
D
f D D
f
f
P E W e w s n
V
u u dV u dx d
f - f f
D
- f f
2 u u 2 u u
W E P W P E
f - f f f
15-Dec-18
21 Central difference method Finite Volume Formulation . . . f d d d f
u dV dV S dV
f x
dx dx dx
D D D
V V
V N
n w P e E W s f f f S d d d d
-
dV
dx dx dx dx
D e w
V
f f f f - -
E P P W
- D D x x
EP PW
15-Dec-18
22 Finite Volume Formulation P E W e w s n S
N f
f f f s a a a
E E W W P P f
f f f f f s a a a a a
S S N N E E W W P P
S dV dV dx d dx d dV u dx d
V x
V V
D f D D
f
f
Finite volume method
15-Dec-18
Difficulty in pressure term discretization Checker board
p - -
dV p p
Solution? e w
x
D
V
p p p p E P P W
-
2
2 N p p
- E W
n w P e E
2 W
s Suhas V Patankar
S Professor Emeritus Univ. of Minnesota
Finite volume method 15-Dec-18 Summary
- Finite volume
- – Solution represent average over the region NOT a point
solution
- Finite volume approach applied to Integral form of
Conservation equation
- Discretization of diffusion and advective terms
- – How to get values of advected quantities at face f
e f w
?
Other alternatives
- – How to resolve pressure discretization ?
Finite volume method
15-Dec-18
Resources Chung T. J. (2002) Computational Fluid Dynamics. Cambridge University Press
- Date A. W. (2005).
- Fox, R. O. (2003) Computational Models for Turbulent Reacting Flows. Cambridge University
Introduction to Computational Fluid Dynamics. Cambridge University Press
- Press Hoffmann K. A. and Chiang S. T. (2000).
- Engineering Education System, Kansas, USA.
- John F. W., Anderson, J.D. (1996)
Computational Fluid Dynamics Vol1, 2 and 3.
Computational Fluid Dynamics: An Introduction Springer Patankar, S. (1980) Numerical Heat Transfer and Fluid Flow. Taylor and Francis
- Ranade, V.V. (2002).
- Academic Press, New York. Versteeg, H.K. and Malalasekera, W. (1995) An Introduction to computational Fluid Dynamics
Computational Flow Modeling for Chemical Reactor Engineering,
- The Finite Volume Method. Longman Scientific and Technical
Finite volume method 15-Dec-18 Web Resources
- http://www.cfd-online.com
- http://en.wikipedia.org/wiki/Computational_fluid_dynamics
- http://www.cfdreview.com/
• https://confluence.cornell.edu/display/SIMULATION/FLUENT
- Learning+Modules
- http://weblab.open.ac.uk/firstflight/forces/#
- NPTEL
- – Balchandra Puranik and Atul Sharma – Srinivaas Jayanthi
Finite volume method
15-Dec-18
Finite volume method
Gratitude
- Dr. Vivek V. Ranade – My Mentor Guide and Teacher
- – iFMg - Research group at NCL, Pune
- Audience
- – For patient hearing and for their thirst in knowledge
15-Dec-18
THANK YOU
A person who never made a mistake never tried anything new
- Albert Einstein
- 1879 -1955
Finite volume method 15-Dec-18 Concept of staggered grid
Finite volume method
15-Dec-18
u uu vu p u u
- m m t x y x x x y y
u uu vu p u u
- m m dt dv dV dV dV dV
t x y x x x y y
D t D
V D
V D
V D
V D V
uu vu p u u m m dv dV dV dV dV
x y x x x y y
D D D D D
V V
V V
V Finite volume method
15-Dec-18
U Control volume
Finite volume method
15-Dec-18
X Momentum Equation
uu vu p u u
m - m dv dV dV dV dV
x y x x x y y
D D D D D
V V
V V
V
uu dv uu uu e w
- x
D
V
- ,I J
uu uu
I
1 , J
-
uu uu uu uu i 1 , J ,i J ,i J i 1 , J
-
2
2 uu uu
- i
1 , J i 1 , J
2 Finite volume method 15-Dec-18 X Momentum Equation . . .
uu vu p u u
m m dv dV dV dV dV
- x y x x x y y
D D D D D
V V
V V
V
vu dV vu vu
- n s
y D
V
vu
- vu
,i j 1 ,i j - -
vu vu vu vu ,i J ,i J 1 ,i J 1 ,i J
-
- 2
2 vu vu
- ,i J
1 ,i J
1
- 2
Finite volume method 15-Dec-18
-
Finite volume method
I V p p dV x p
J ,
m
m
D D D D D
V
V V
V V
dV y u y dV x u x dV x p dV y vu dv x uu
- D
-
1 I J ,
- X Momentum Equation . . .
15-Dec-18
-
D
m
m
- m
w e
m
2 u u 2 u u x u x u
J , J 1 i , i J , 1 i J ,
J 1 i , i J , i J , 1 i J ,
I X Momentum Equation . . .
Finite volume method
V x u x u dV x u x
m
m
D D D D D
V
V V
V V
dV y u y dV x u x dV x p dV y vu dv x uu
- m
- m
1 I J ,
- 2 u u 2 u
- m
-
- m
-
-
15-Dec-18
-
- m
m
m
D
s n
m
2 u u 2 u
2 u u 2 u u y u y u
, 1 J i J , i , 1 J i , 1 J i J , i J , i , 1 J i
, j i , 1 j i
X Momentum Equation . . .
Finite volume method
V y u y u dV y u y
m
m
D D D D D
V
V V
V V
dV y u y dV x u x dV x p dV y vu dv x uu
- m
- m
-
-
- m
-
- m
15-Dec-18
-
m
m
D D D D D
V
V V
V V
dV y u y dV x u x dV x p dV y vu dv x uu
1 I J ,
I J , i J , i p p au u a
J ,
Final form
-
Finite volume method