fluid structure interaction (fsi) with rbf morph generic...
TRANSCRIPT
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Fluid Structure Interaction (FSI) with RBF Morph
Generic Formula 1 Front Wing
• Outline
• RBF Morph Tool Presentation
• Industrial FSI application
• Conclusions
Dr. Marco Evangelos Biancolini
University of Rome “Tor Vergata”
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
RBF Morph Tool Presentation
• Morphing & Smoothing
• The Aim of RBF Morph
• RBF Morph Features
• Background
• How It Works
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Morphing & Smoothing
• A mesh morpher is a tool capable to perform mesh modifications, in order to achieve arbitrary shape changes and related volume smoothing, without changing the mesh topology.
• In general a morphing operation can introduce a reduction of the mesh quality
• A good morpher has to minimize this effect, and maximize the possible shape modifications.
• If mesh quality is well preserved, then using the same mesh structure it’s a clear benefit.
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
The Aim of RBF Morph • The aim of RBF Morph is to perform fast mesh morphing using a mesh-independent
approach based on state-of-the-art RBF (Radial Basis Functions) techniques.
• The use of RBF Morph allows the CFD user to perform shape modifications, compatible with the mesh topology, directly in the solving stage, just adding a single command line in the input file
• The final goal is to perform parametric studies of component shapes and positions typical of the fluid-dynamic design like:
• Design Developments
• Multi-configuration studies
• Sensitivity Studies
• DOE (Design Of Experiment)
• Optimization
(rbf-morph ‘(("sol-1" amp-1) ("sol-2" amp-2)...("sol-n" amp-n)))
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
RBF Morph Features
• Add on fully integrated within Fluent (GUI, TUI & solving stage) and Workbench
• Mesh-independent RBF fit used for surface mesh morphing and volume mesh smoothing
• Parallel calculation allows to morph large size models (many millions of cells) in a short time
• Management of every kind of mesh element type (tetrahedral, hexahedral, polyhedral, etc.)
• Support of the CAD re-design of the morphed surfaces
• Multi fit makes the Fluent case truly parametric (only 1 mesh is stored)
• Precision: exact nodal movement and exact feature preservation.
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Background: RBF Theory • A system of radial functions is used to fit a solution for the
mesh movement/morphing, from a list of source points and their displacements. This approach is valid for both surface shape changes and volume mesh smoothing.
• The RBF problem definition does not depend on the mesh
xxxx hsN
i
ii 1
• Radial Basis Function interpolation is used to derive the displacement in any location in the space, so it is also available in every grid node.
• An interpolation function composed by a radial basis and a polynomial is defined.
zyxh 431 x
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
How it Works: the work-flow
• RBF Morph basically requires three different steps:
• Step 1 [SERIAL] setup and definition of the problem
(source points and displacements).
• Step 2 [SERIAL] fitting of the RBF system.
• Step 3 [SERIAL or PARALLEL] morphing of the surface
and volume mesh (available also in the CFD solution
stage).
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
How it Works: the problem setup
• The problem must describe correctly the desired changes
and must preserve exactly the fixed part of the mesh.
• The prescription of the source points and their
displacements fully defines the RBF Morph problem.
• The problem is mesh-independent, and could be defined
using grid nodes as well as arbitrary point locations.
• Each problem and its fit define a mesh modifier or a
shape parameter.
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
How it Works: the interface
• One of the key aspects of RBF Morph, in respect to FLUENT
integration, is related to the ability of extracting information from
the FLUENT mesh and to the
user interface GUI
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Let RBF-Morph talk now!
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Mo
torb
ike
Win
dsh
ield
(Bri
co
mo
to,
MR
A)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Fo
rmu
la 1
Fro
nt
Win
g
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Sail
s T
rim
(Ig
na
zio
Ma
ria V
iola
,
Un
ivers
ity o
f N
ew
cas
tle)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Caro
tid
Bif
urc
ati
on
(Oro
bix
– C
ILE
A)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
En
gin
e A
ir b
ox s
ha
pe
(ST
V F
SA
E T
ea
m)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Ge
ne
ric
Fo
rmu
la 1
Fro
nt
En
d
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Ge
ne
ric
Fo
rmu
la 1
Fro
nt
En
d
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Co
mp
res
so
r B
lad
e
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Sh
ip H
ull
(U
niv
ers
ity o
f L
ee
ds
)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Sh
ip H
ull
(U
niv
ers
ity o
f L
ee
ds
)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
MIR
A R
efe
ren
ce c
ar
(MIR
A l
td)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Industrial FSI application
• Challenge
• Test Case Description
• Solution
• Morphing and FSI Set Up
• Results
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Challenge: Fast FSI Tool.
• CFD calculations are usually performed
considering the undeformed wing
configuration (i.e. rigid parts)
• When important effects are observed (wing
deformation and rotation) the CFD model
should be updated to the deformed
configuration.
• Even a slight deformation can have a
dramatic effect on performances (Drag, Lift,
Tyre-Wing interaction,…).
• A feasible solution is given by Fluent + RBF
Morph: the CFD model parameterized using
modal shapes becomes flexible!
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Test Case Description: Generic F1 Front End
• Attention is focused on the front wing that is connected to the body by means of two pylons
• The wing is composed by two profiles (Main and an adjustable Flap)
• Transversal flow is confined by the End Plate and a Fence
• Compliance of parts is critical! Loads are very high and even small deflections can affect the wing performance (drag, lift, wing tyre interaction)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Solution: Modes Embedding with RBF Morph
1. Modal shapes are calculated using FEA
2. Fluid mesh is parameterized using modal shapes by RBF Morph each mode is stored as a standard shape modifier
3. fmorph module is initialized at the beginning of CFD parallel run
4. Modal Forces are integrated onto the CFD mesh within Fluent
5. The amplification of each mode is obtained dividing the modal force for the squared circular frequency
6. CFD mesh is updated using known amplifications
7. The CFD model becomes elastic i.e. is capable to update its shape using actual pressure with a single command
8. Usually the shape is updated during CFD iterations (typical updating interval is 25)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Problem Definition
• Fluent Mesh: tet + 3 prisms layers 3167964 cells
• Steady simulation iterated until stable forces are achieved
• FEM modeling with ANSYS Mechanical (static + modal)
• Equivalent steel thickness to have 7 mm deflection at 126 kph
• Full coupled 2 ways simulation used as a reference
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
RBF Morph Set Up (using GUI)
• A domain Encap around the wing is used to limit the morphing action
• The FEM field is imposed to all the threads on the wing and pylons
• A zero movement is imposed to constraint the remaining threads (body, wheel, ground)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
FSI Model Set up (using TUI)
• RBF Morph set-up used for first mode is replicated in batch for all required modes
• The modal approach is enabled during solution using the command (rbf-fmorph-init); it should disabled at the end with (rbf-fmorph-end)
• Mesh updating using modal approach is enabled adding a single calculation activity (modal-q-update-static)
(define (modal-q-update-static)
;; calculate modal forces
(set! modal-forces (rbf-fmorph-forces '("front_wing_flap" ... "fin")))
;; update q = F / k
(set! modal-q (map / modal-forces modal-k))
;; update mesh
(rbf-fmorph (list (list "mode1-new" (list-ref modal-q 0)) ...)))
)
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Results: Morphing with 5 Modes
• Modes are
normalized
with respect to
mass
• Each mode is
previewed in
the interval
0-0.01
• Actual
amplifications
depends on
pressure
loads!
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
• Each mode refine
the deformation
• With five modes
the error is less
than 0.2 mm
(3%)
• Loads are
affected by
elastic
deformation
(drag 10% lift
1.5%)
Mode Max d(mm) Max err(mm) Max err (%)
1 5,58 1,61 22,39
2 6,33 0,86 12,00
3 6,34 0,85 12,15
4 6,53 0,66 9,50
5 7,00 0,19 2,76
2 Ways FSI 7,19 0,00 0,00
Part Fx (N) Fy (N) Fz (N) dFx (%)
dFy (%)
dFz (%)
Fin 1,00 1,21 0,07 -0,52 2,93 1,21
Flap 30,56 -0,38 -67,30 3,84 -23,15 0,35
Main 12,61 6,48 -319,94 30,60 -2,22 1,73
Plate 5,45 11,48 -19,37 5,12 -1,18 1,07
Vane 4,95 19,23 -0,71 3,41 1,70 -1,50
Total 54,57 38,02 -407,25 10,04 0,45 1,46
Results: mode convergence, loads (126kph).
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Resu
lts
: e
ffec
t o
f sp
ee
d
(54
-16
2k
ph
).
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Resu
lts
: e
ffec
t o
f sp
ee
d
(54
-16
2k
ph
).
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Remarks Performances
• Loads are affected by structural
deformation
• Modal approach makes the CFD
model parametric with respect to
structural dynamics modes, i.e.
flexible.
• All calculations performed on a small
Hybrid mesh (tet+prisms) 3.2
millions cells using a laptop
(Fluent13 on Linux platform, RBF
Morph 1.3)
• Similar performances are expected
for larger models running on larger
calculation facilities (RBF Morph is
fully parallel)
• Transient implementation available
• CPU* Time to fit each mode
(120.000RBF points) 190 s
• CPU Time to init 5 modes 117 s
• CPU Time for each mesh update
using 5 modes 3 s
• CPU Time for a CFD iteration 15 s
• User Time to set-up modes (FEM
+ RBF Morph) 1/2 day
• User Time to set-up CFD + modal
simulation 1/2 day
• In transient analysis the mesh
can be updated at each time step
(but with MDM extra cost!)
*one Intel® Centrino2 dual-core processor, 2.26GHz 8GB
www.rbf-morph.com
RBF Morph, an ANSYS Inc. Partner
2011 EnginSoft International Conference
20 - 21 October Verona
Fluid Structure Interaction (FSI) with RBF Morph
Generic Formula 1 Front Wing
Thank you for your
attention!
Dr. Marco Evangelos Biancolini
E-mail: [email protected]
Web: www.rbf-morph.com