26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 1 Fluid-Structure Interaction Modelling with Europlexus Fast Dynamics

26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis1

Fluid-Structure Interaction Modelling with Europlexus Fast Dynamics Software

S. PotapovEDF R&D – Analyses in Mechanics and Acoustics

Colloque GDR Interaction Fluide-StructureSophia Antipolis, 26-27 September 2005


Outline

• Industrial context

• Numerical tool

• Incompatible FS interface

• Validation example

• Conclusion


Loss Of Coolant Accident (LOCA)

Bran ch e ch au d e (BC)

Bran ch e en U (BU)

Bran ch e froid e (BF )

Pom p e p rim aire (PP)

Cu ve

G én érateu r d e vap eu r (G V)

Main Primary Circuit of PWR

Fond de cuve

Coeur Dérivation coeur

Collecteur annulaire

Ajutagesd'entrée

Ajutagesde sortie

Plenumsupérieur

Volumesous couvercle

Volumed'entrée

Reactor vessel

PP3

PP4

PP1PP2

Cuve

GV2

GV3

GV1

GV4

Boucle 2

Boucle 3

Boucle 1

Boucle 4

PP3

PP4

PP1PP2

Cuve

GV2

GV3

GV1

GV4

Boucle 2

Boucle 3

Boucle 1

Boucle 4

Pipeline model

Mixed pipeline / 3D model

1D/3D Fluid-Structure link

butées brèchebutées brèche

PP GV

breakanti-whipping devices


transient phenomena (wave propagation) fluids, structures and their interaction (FSI) Lagrangian, Eulerian and ALE formulations geometric and material non-linearities 1D, 2D, and 3D modelling (1D/3D connexions) finite element formulation + transport terms explicit time integration

(initiated by CEA in 1978, and developed jointly by CEA, JRC, EDF, SAMTECH since 2000)

Domains of analysis: Applications:

Main characteristics:

1) pipe circuits

2) hydrodynamics

3) explosions

4) impacts

5) robotics

- nuclear reactors

- chemical plants

- off-shore structures

- submerged pipelines

- safety valves

Principal models available

for the FSI analysis:

• gas (perfect)• two-phase water - homogeneous equilibrated - steam tables• pressure losses (distributed)

• multi-pipe links:

• pump, break, local pressure losses

• pipes:

1D elements :

rigid and flexible walls

3D fluid and structure elements

Compressible fluid materials:

• tetrahedron, cube• beam, plate, shell• 1D-3D F and S connexions

EUROPLEXUS fast dynamics code


3D Fluid-Structure coupling in EUROPLEXUS

nF

r-r

S

equality of reactions

n F

vS S

vF

compatibilitycondition

Structure

Fluid

compatiblemeshes

C v = b

M ü = Fext - Fint

m n ü n = fext - fint + r nn n

Dynamic equilibrium over the whole domain:

Kinematic links:

Equilibrium for the FS interface d.o.f.:

r n = C T Reactions at the FS interface: vF .n = vS .nFor inviscid fluid:

Structure

Fluid

Hierarchical type interface

Incompatible FS interfaces:

(a) (b) (c) (d)


Non-matching coupling conditions

**

1( )

n

Si SiS iN S

v v

*F F FS v n v n

*

1[ ( ) ] 0

n

F F Si Si FiN S

v n v n

noeud

point

noeud

point

node

*F S v n v n


FSI simulation of LOCA accident in HDR

HeissDampfReaktor (KFA/ISR, Germany, 1980)

Blowdownnozzle

Core barrel

Downcomer

Mass ring

Pressurevessel

Lower plenum

Membrane

Blowdown nozzle:L = 1.37 mA = 0.0314 m2

Core barrel:H = 7.57 mR = 1.32 mt = 0.023 m

Mass ring:M = 13500 kg

(Superheated Steam Reactor)

Experiment V32 Initial conditions:

Brèche

Eau souspression

P = 15.5 MPaT = 300 °C

Brèche

Eau souspression

P = 15.5 MPaT = 300 °C

break

waterP = 11 MPaT = 300 °C


HDR model with EUROPLEXUS

Coarse mesh

Fine mesh

Refinmentprocedure

Fluidmesh

Incompatible interface

Structuremesh

Nb. of elements :

Fluid : 35854 Fluid : 34204Structure: 2080 Structure: 1148


Evolution of pressure

compatible mesh incompatible meshP x 0.1 (MPa)

P x 0.1 (MPa) P x 0.1 (MPa) P x 0.1 (MPa)


Time histories of pressure and displacements

-2,0

-1,5

-1,0

-0,5

0,0

0,5

1,0

0 10 20 30 40 50

Time (ms)

Dis

pla

cem

ent

(m)

Experiment (Test V32)

Europlexus (matching meshes)

Europlexus (non-matching meshes)

KS1026

-0,2

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

0 10 20 30 40 50

Time (ms)

Dis

pla

cem

ent

(m)



Europlexus (non-matching meshes) KS1002

8,0

8,5

9,0

9,5

10,0

10,5

11,0

11,5

0 10 20 30 40 50Time (ms)

Pre

ssu

re (

MP

a)




BP9136

8,0

8,5

9,0

9,5

10,0

10,5

11,0

11,5

0 10 20 30 40 50Time (ms)

Pre

ssu

re (

MP

a)




BP9140


Calculations with and without FSI

8,0

8,5

9,0

9,5

10,0

10,5

11,0

11,5

0 10 20 30 40 50Time (ms)

Pre

ssu

re (

MP

a)


Europlexus (FSI calculation)

Europlexus (rigid structure)

BP9133

8,0

8,5

9,0

9,5

10,0

10,5

11,0

11,5

0 10 20 30 40 50Time (ms)

Pre

ssu

re (

MP

a)




BP8302

-2,0

-1,5

-1,0

-0,5

0,0

0,5

1,0

0 10 20 30 40 50

Time (ms)

Dif

fere

nti

al p

ress

ure

(M

Pa)




KP0032

-2,0

-1,5

-1,0

-0,5

0,0

0,5

1,0

0 10 20 30 40 50

Time (ms)

Dif

fere

nti

al p

ress

ure

(M

Pa)




KP0040


Time performance

Matching mesh:

Fluid: 35854 FE Fluid: 34204 FEStructure: 2080 FE Structure: 1148 FE

Non-matching mesh:

Case Mesh type

Number of elements

(F/S)

Nomber of time steps

CPU time [h]

CPU time ratio

Speed-up

factor

A Compatible 35854/2080 41981 216 1.00 -

B Incompatible 34204/1148 15269 35 0.16 6.2

on Compaq

25

4


• The use of the new non-matching FS interface algorithm allows realistic prediction of different physical phenomena characterising the LOCA situation

• This algorithm allows optimising physical modelling and mesh generation for the fluid and structure domains

• The CPU time is drastically reduced

Conclusion

Documents

26-27 September 2005 Colloque GDR Intéraction Fluide-Structure, Sophia Antipolis 1 Fluid-Structure Interaction Modelling with Europlexus Fast Dynamics