Download Problem 37: FSI analysis of a simplified turbine using a

Problem 37: FSI analysis of a simplified turbine using a sliding mesh
Problem description
A simplified turbine is immersed in a fluid as shown:
Inlet
Structure
Structure rotates freely
about center pin
Outlet
At the beginning of the analysis, the turbine is at rest. A normal traction is suddenly imposed
at the turbine inlet. The fluid flows through the turbine housing, causing the turbine to rotate.
The model is planar and two-dimensional.
Because the turbine can rotate an arbitrary amount, it is convenient to model fluid surrounding
the turbine with elements that rotate with the turbine. These elements slide past the elements
that are near the turbine housing, as shown:
Mesh in this region
rotates with structure
Sliding boundary
Mesh in this region is
stationary
Fluid is allowed to flow through the sliding mesh boundary.
ADINA R & D, Inc.
37-1
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
In this problem solution, we will demonstrate the following topics that have not been
presented in previous problems:
• Defining a boundary condition of type sliding-mesh
Before you begin
Please refer to the Icon Locator Tables chapter of the Primer for the locations of all of the
AUI icons. Please refer to the Hints chapter of the Primer for useful hints.
This problem cannot be solved with the 900 nodes version of the ADINA System because the
900 nodes version of the ADINA system does not contain ADINA-FSI.
Note that you must have an ADINA-M license to do this problem. In addition you should be
able to allocate as much memory as possible to the AUI, at least 400 MB. This memory is
needed to perform the particle tracing at the end of this problem description.
Much of the input for this problem is stored in files prob37_1.in, prob37_2.in,
prob37_3.in and prob37_1.plo. You need to copy file prob37_1.in, prob37_2.in,
prob37_3.in, prob37_1.plo from the folder samples\primer into a working directory or
folder before beginning this analysis.
Invoke the AUI and set the Program Module drop-down list to ADINA CFD. Choose
EditMemory Usage and make sure that the ADINA/AUI memory is at least 400 MB.
ADINA CFD model
Defining model control data, geometry, wall boundary condition
We have prepared a batch file (prob37_1.in) that performs the following operations:
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Specifies a transient FSI analysis.
Specifies the time stepping
Defines points, lines and surfaces.
Defines a sheet body
Defines a wall boundary condition
Plots the model
Choose FileOpen Batch, navigate to the working directory or folder, select the file
prob37_1.in and click Open. The graphics window should look something like the figure on
the next page.
37-2
ADINA Primer
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
TIME 24.00
Z
X
B
B
Y
B
B
B
B
V V
B
B
B
B
2
3
P
WAL
1
Defining the sliding-mesh boundary conditions
The following figure shows the lines and edges on the sliding-mesh boundaries:
L10
L11
E12
L9
L12
L16
E11
Figure includes
gap between regions
for clarity.
L15
L13
Regions overlap slightly
in actual model.
L14
Although the figure shows a slight gap between the two meshes, actually the two meshes
overlap slightly.
ADINA R & D, Inc.
37-3
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
Click the Special Boundary Conditions icon
, add condition number 2 and set the Type to
Sliding Mesh. Set the ‘Apply to’ field to Edges, then enter 12, 11 in the first two rows of the
table and click Save. Add condition number 3 and make sure that the Type is Sliding Mesh.
Set the ‘Apply to’ field to Lines, enter line numbers 9 to 16 in the first eight rows of the table,
then click Save (do not close the dialog box).
We also need to create a boundary condition pair to link the two boundary conditions of type
sliding-mesh. Click the Boundary Condition Pair button, and, in the first row of the table, set
B.C. #1 to 2 and B.C. #2 to 3, then click OK twice to close both dialog boxes.
, the graphics window should look something like this:
When you click the Redraw icon
Z
TIME 24.00
X
D
Y
C
D
C
D
C
D
B
C
C
B
D
C
C
D
C
D
D
V V
B
C
D
B
C
D
2
3
P
WAL SLI
2
3
1
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Finishing the ADINA CFD model definition
We have prepared a batch file (prob37_2.in) that performs the following operations:
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37-4
Defines remaining special boundary conditions
Defines leader-follower relationships
Defines the material
Defines the normal-traction loading
Defines the element groups
Subdivides the geometry
Meshes the geometry
Creates the prob37_f.dat file
ADINA Primer
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
►
Regenerates the graphics
Choose FileOpen Batch, navigate to the working directory or folder, select the file
prob37_2.in and click Open. Close the Log Window dialog box (which is displayed when
the AUI creates the data file). The graphics window should look something like this:
TIME 24.00
Z
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
EEEEEEEE
X
Y
EEEEE C
E
CBB
CBBC
BBBBB
CBBCC
BBB
C
BBBB
BBB
EEE
EEEE B
B
C
CBBC
B
E
B
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B
C
BBBC
EE
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EE C
BB
CDD
C
EEEE
B
B
E
D
D
B
B
E
E
B
B
C
E B
BBC
BB
BBB EEEEEEEEEEE
DDD
EEE B
BBC
C
C
EEE EEEE
BBB
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BB
C
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EEEE
D D
BBB
EE BC
E
CB EEEE
B
EE EB
B
BC EE E EEEEEEE
D
D
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CBBB
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BB EEEE
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B
B
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C
C
E
E B
B
B
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D
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E
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E
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DDDD
C
C
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B
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D
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C
C
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E
E
B
B
PRESCRIBED
D
E
E
B
B
D
D
DD
D
D
E
E
B
B
C
C
D
D
E
E B
B
B
NORMAL_TRACTION
D
D
E
B
D
D
E
DDDDDDDD B
C E
E C
B DDDDDDDD
E
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B
B
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D
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TIME 24.00
B
B
E
E
D
D
B
B
E
D B
C E
C
D
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B
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E
C
D
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B
B E
E
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D
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B
B
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D
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C
C
B
B
E
E
D
D
D
D
D
D
B
B
E
E
10000.
D
D
B
B E
E
E
D
D
C
C
B
B
D
D
E
D
D
B
B
E
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D D
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BB EE
EE BB
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V V P
EE C
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2 3
EE C
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D D
BC
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EE BBC
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WAL FSI SLI
E
E
E
E
E
E
E
E
E
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B 2
E
E
E
E
E
E
C 3
D 4
E 1
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Click the Save icon
and save the database to file prob37_f.
ADINA Structures model
Click the New icon
to begin a new model.
We have prepared a batch file (prob37_3.in) that creates the entire ADINA Structures model.
Choose FileOpen Batch, navigate to the working directory or folder, select the file
prob37_3.in and click Open. Close the Log Window dialog box (which is displayed when
the AUI creates the data file). The graphics window should look something like the figure on
the next page.
ADINA R & D, Inc.
37-5
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
TIME 1.000
Z
X
Y
B
B
B
U U
2 3
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Running ADINA-FSI
Choose SolutionRun ADINA-FSI, click the Start button, select file prob37_f, then hold
down the Ctrl key and select file prob37_a. The File name field should display both file
names in quotes. Then click Start.
The ADINA-FSI solution takes 120 steps.
When ADINA-FSI finishes, close all open dialog boxes. Set the Program Module drop-down
list to Post-Processing (you can discard all changes), click the Open icon
and open
porthole file prob37_f. Then click the Open icon
and open porthole file prob37_a. The
graphics window should look something like the figure on the next page.
(Your results may be slightly different than ours because free meshing produces different
meshes on different platforms.)
37-6
ADINA Primer
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
Z
TIME 24.00
X
Y
Post-processing
Visualizing the mesh motion: Click the Movie Load Step icon
, then the Animate icon
. Notice that the mesh surrounding the turbine rotates along with the turbine, and slides
relative to the mesh close to the turbine housing. Click the Refresh icon
animation.
Velocity vectors: Click the Model Outline icon
to clear the
, then click the Quick Vector Plot icon
. To clear the stress vector plot in the structure, click the Modify Vector Plot icon
,
make sure that the Vector Quantity is STRESS, click the Delete button, click Yes to confirm,
then click OK to close the dialog box. The graphics window should look something like the
figure on the next page.
Click the Movie Load Step icon
vectors.
, then the Animate icon
to animate the velocity
Notice that the velocity vectors cross the sliding-mesh boundary. Click the Refresh icon
to clear the animation.
ADINA R & D, Inc.
37-7
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
TIME 24.00
Z
X
Y
VELOCITY
TIME 24.00
3.627
3.250
2.750
2.250
1.750
1.250
0.750
0.250
Particle tracing: We can use the particle tracing feature to visualize the fluid motion.
First click the Clear Vector Plot icon
to remove the velocity vectors.
We have put the necessary commands for the particle tracing in a batch file (prob37_1.plo).
Choose FileOpen Batch, navigate to the working directory or folder, select the file
prob37_1.plo and click Open. The graphics window should look something like the top
figure on the next page.
At this point, the particle tracing has only been computed for the first time step. Now click
the Movie Load Step icon
to compute the particle traces for the entire solution. (This
calculation may take a long time. Increasing the memory available to the AUI should speed
up the calculation.) When the movie is complete, click the Animate icon
window should look something like the bottom figure on the next page.
37-8
. The graphics
ADINA Primer
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
TIME 0.2000
Z
X
Y
PARTICLE TRACE
UNSTEADY FLOW, TIME = 0.2000
MULTIPLE PARTICLES/EMITTER
EMIT INTERVAL = 0.02000
START TIME = 0.000
TIME 24.00
Z
X
Y
PARTICLE TRACE
UNSTEADY FLOW, TIME = 24.00
MULTIPLE PARTICLES/EMITTER
EMIT INTERVAL = 0.02000
START TIME = 0.000
Notice how the particles cross over the sliding mesh boundaries.
ADINA R & D, Inc.
37-9
Problem 37: FSI analysis of a simplified turbine using a sliding mesh
Click the Refresh icon
to clear the animation. You can also use the icons that change the
solution time to view the particle traces at different solution times.
Exiting the AUI: Choose FileExit (you can discard all changes).
Notes
If there is a slight gap between the two meshes, the sliding-mesh feature will still work.
However, during particle tracing, if a particle enters the gap, it is lost and never reenters the
model.
The two meshes must be incompatible (that is, they cannot share nodes). One convenient way
to generate incompatible meshes is to use separate element groups for the two meshes, then
set the Coincidence Checking to Group during meshing of the second element group.
Unsteady particle tracing is very memory-intensive. The memory allocated to the AUI should
ideally be set to the amount of RAM (physical memory) on your computer.
37-10
ADINA Primer