Fluid-based Topology Optimization of an EGR...
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1 3DS.COM © Dassault Systèmes | Confidential Information | 4/7/2014 | ref.: 3DS_Document_2013 3DS.COM © Dassault Systèmes | Confidential Information | 4/7/2014 | ref.: 3DS_Document_2013 Fluid-based Topology Optimization of an EGR Flowsplitter
Transcript of Fluid-based Topology Optimization of an EGR...
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Fluid-based Topology
Optimization of an
EGR Flowsplitter
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1 Problem Description
2 Method Description
3 Optimization Setup
4 Optimization Results
5 STAR-CCM+ Adjoint Solver
Overview
6 Summary
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Objective
Consideration of massflow balancing
+ reduction of total pressure loss
Topology optimizer is used to consider
the named objectives starting from the
available design space
Constraint: Obtained geometry may
no violate the design space
boundaries
Flowsplitter geometry
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Both groups have their strengths → The right method depends on the given optimization task
Optimization methods
Non-Parametric
Methods
Parametric
Methods
Combination of
both Groups
Sizing &
par. Shape
DOE &
RSM Robustness
Reliability
Geometric
Parameter
MDO
Structural
Topology
Structural
Shape
Bead
Fluid
Topology
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Tosca Products inside of 3DEXPERIENCE platform
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Topology optimization for CFD problems (1) Optimization problem is based on the
(meshed) available design space
initi
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Topology optimization for CFD problems (2) Optimization problem is based on the
(meshed) available design space
Geometric variation is achieved by
sedimenting individual cells
initi
al d
esig
n po
ssib
le v
aria
nts
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Topology optimization for CFD problems (3) Optimization problem is based on the
(meshed) available design space
Geometric variation is achieved by
sedimenting individual cells
An individual design proposal can be
derived based on the collectivity of all free
(= non-sedimented) cells
Optimization represents a co-simulation.
New design available after 1 single CFD
run
initi
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ssib
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aria
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Tosca Fluid – Convergence behaviour
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Tosca Fluid setup
Optimization Setup
Co-simulation with STAR-CCM+ V 8.06.005 +
TOSCA Fluid 2.3
Defined iteration number: 25000
Optimility criteria with backflow tolerance: 0.5
Simulation time: 24.0 hrs with 2CPU
Result Extraction
Sedimentation + Unsedimented
Smoothing of the extracted geometry Designspace geometry
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Tosca Fluid „raw“-result Obtained geometry after usage of STAR-CCM+ Surface Wrapper
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Tosca Fluid „raw“-result - Streamlines Results
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Basedesign - Streamlines Results
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Comparison of outlet velocity field
Tosca Fluid design Basedesign
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Comparison basedesign vs. Tosca Fluid design Tosca Fluid result = blue geometry
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Comparison basedesign vs. Tosca Fluid design Total pressure loss + massflow split ratio + uniformity
Basedesign Tosca Fluid
Result
Total pressure
loss
1820 Pa 610 Pa
Split ratio 45.9 : 54.1 49.1 : 50.9
Uniformity 0.832 : 0.841 0.946 : 0.940
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Redesign with CAD tool
Designspace
Smoothed TOSCA Fluid result
CAD-based Redesign
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Redesign workflow
1. Wrapped TOSCA result
4. Automatic Surface
2. Delete needless features
3. Fill hole + smooth
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Tosca Fluid „raw“-result - Streamlines Results
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Redesign - Streamlines Results
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Comparison of outlet velocity field
Tosca Fluid design Basedesign
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Comparison basedesign vs. Tosca Fluid design Total pressure loss + massflow split ratio + uniformity
Basedesign Tosca Fluid
Result
Total pressure
loss
1820 Pa 541 Pa
Split ratio 45.9 : 54.1 48.6 : 51.4
Uniformity 0.832 : 0.841 0.931 : 0.932
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Further improvement with STAR-CCM+ sensitivities
• Geometrie: Redesigned Tosca Fluid result
• Primal solution + ajoint flow analysis with coupled solver • Coupled solver: CFL = 200, Grid sequencing and Expert Driver
• Objective function: Pressure drop
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Pressure drop based sensitivities
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Subdivision of surface + morphing • Subdivision of surface into
• Two surfaces modified by morpher
• Remaining part, that will not be changed
• Definition of two lines with the design
points
• Calculation of the design points‘
displacements on the basis of the mesh
sensitivities
• Mesh deformation based on the mesh
sensitivities
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Sensitivity based morphing
Original surface Morphed surface
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Original surface
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Morphed surface
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Loss behaviour of morphed Tosca Fluid result
Tosca Fluid
Result
Morphed
Geometry
Total pressure
loss
541 Pa 521 Pa
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Basedesign Tosca Fluid design Morphed design
Basedesign
Tosca Fluid design
Morphed design
Total pressure loss (Pa)
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Summary Objective: Balanced mass flow at the 2 outlets and reduction of total pressure
loss
TOSCA Fluid optimization based on available design space (24 hrs.)
Simulation results of design proposal reveal significant reduction of total
pressure loss + improvement of flow balancing
Final redesign shows a nearly balanced flow distribution + significant total
pressure loss reduction + increased uniformity
With the STAR-CCM+ adjoint solver, a further reduction (-4%) of the total
pressure loss can be achieved by a sensitivity based morphing
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CFD setup Topology-Optimization
Solver: STAR-CCM+ 8.06.005
Physics:
Incompressible
Steady
k-ε turbulence, All y+
Boundary conditions:
Inlet: Massflow inlet
Outlet: Flow-Split Outlet
Verification
Solver: STAR-CCM+ 8.06.005
Physics:
Incompressible
Steady
k-ε turbulence, All y+
Boundary conditions:
Inlet: Massflow inlet
Outlet: Pressure outlet
