Aut utom omotiv tive e Ind ndustr ustry Frederic derick k J. - - PowerPoint PPT Presentation

Impact act of STAR-CCM CM+ + v7.0 in the Aut utom

• motiv

tive e Ind ndustr ustry Frederic derick k J. Ross, ss, CD-ada adapc pco Direct ector

• r,

, Ground nd Transpor nsporta tatio tion

Vehic icle le Simulation mulation Compone ponent nts

2

Vehicle Aerodynamics

• Design Studies
• Aeroacoustics
• Water/Dirt Management

Vehicle Thermal Management

• Front End Cooling
• Component Temperature Prediction

Cabin Simulations

• HVAC
• Deice/Defog
• Passenger Thermal Comfort

Manufacturing Simulations

• Paint Dipping
• E-coat

Vehic icle le Simulation mulation Compone ponent nts

3

Vehicle Aerodynamics

• Design Studies
• Aeroacoustics
• Water/Dirt Management

Vehicle Thermal Management

• Front End Cooling
• Component Temperature Prediction

Vehic icle le Simulation mulation Compone ponent nts

4

Vehicle Aerodynamics

• Design Studies
• Aeroacoustics
• Water/Dirt Management

Vehi ehicle cle Aerod

• dynamics

ynamics News ws

Unsteady Aerodynamics

• When to use?

Reducing Turn-around Time

• Taking Advantage of Coupled Solver for reducing
• Automation

Water/Dirt Management

• New wall film model in STAR-CCM+ being used for water management

Should

• uld we us

use steady ady or un unsteady eady simulat ation? ion? – Statement: Vehicle Aerodynamics is Unsteady

True Statement

• Use turbulence model to capture the unsteady nature
• Model the Unsteady structures using LES type model

– Statement: Need to have the right physics to get the correct solution

• LES Models physics more accurately

– Flow structure capture depends upon: »Grid Size/Time Step Size – Wall interaction: 2 Layer »20-25 layers – Drag value is based upon a time average »Time length really depends on vehicle Example: Class 8 trucks: 10-30 seconds

Steady eady vs vs Uns Unstead eady y Simulation mulation

S-Cl Clas ass Sedan dan

– Model

• A-pillar noise generation: target size 1mm
• Side Window, Tire Wakes: Resolve to 2mm
• Boundary layer on exterior: 2-Layer on wall. 20 layers

Model Size: 500,000 million cells

– Computer Resource

• High Performance Computing Center Stuttgart (HLRS)
• Cray XE6 Supercomputer

– 3552 compute nodes 113664 cores

Status: Currently running on cluster

Sample ple Stud udy

Direct ct Ed Eddy y Simu mulat ation ion (DES ES) ) allows ws large e struc uctu tures res with th LES ES while le small ll, , un under der-res resolve e regions ions with th RAN ANS

Positive Features

• Capture large wake structures on typically able to be replicated with pure RANS

solution

• Reduces the need for fine grid to capture small structures

– RANS can be used in regions of coarse grid

• Can run with larger time step

Negative Features

• Still require long transients to get time averaged solution

RANS S Compr promi

• mise

se (DES ES)

Run unnin ning g pur ure steady ady reduc duces s run un time

Positive Features

• Reduced Run Time
• Accurately models flow approach to the vehicle
• Accurately captures separation points

– Still recommended 2-Layer grid for boundary layer development and prediction of separation.

• Do not need to run long for averaging of results.
• Not as sensitive to grid density

Drawbacks

• Not time accurate
• Wake structures not correctly produce

– Not ideal for multi-vehicle drag prediction – Looking at curvature correction to improve wake structures, but there is a limit to how far these will take us.

RANS S Solut ution ion

Det etail il Ex Experime rimenta ntal l data was taken en for a g generic neric truc

• uck. Purp

urpose se was to help p test t and valida date e CFD

Ran case with full Yaw Sweep:

• 0,1,2,3,4,5,7,9,7,5,4,3,2,1,0

Between 2-3 degrees, solution is not stable

Exam ample ple 2: GCM Truck ck Benchmar hmark

Det etail il Ex Experime rimenta ntal l data was taken en for a g generic neric truc

• uck. Purp

urpose se was to help p test t and valida date e CFD

RANS matches fairly well to Yaw study

• Results are not symmetric, and only

half yaw sweep completed

Averaged RANS fits reasonably on Yaw sweep

• In location of high instability with

RANS, running unsteady solver may provide higher time accurate result

• Alternative: can look at case using

DES

GCM Truck ck Benchmar hmark

0.3 0.4 0.5 0.6 0.7 0.8

• 15
• 10
• 5

5 10 15 Exp STAR- CCM+

DES Flow Animation

Uns Unstead eady y Simulations mulations

DES Sim imulat lation ion

Where e DES S is being g used:

– Aeroacoustic Studies – Examining Rotating Wake Interactions

• Fans, Blowers, Wheels

– Vehicle Handling

Star ar-CCM CM+ + v7.02: Overse set t Grids ds More e comple lex passing sing requires uires more re comple lex grid d motio tion. n.

– Studies have used rotating regions to aid in simulation of

• vertaking.

– Mesh morphing has been used to change ride height. – Overlapping grids can simplify grid motion in the future. DES Sim imulat lation ion

Where here Steady eady RAN ANS S solutions utions are being ng us used? ed?

Vehicle Design Tool Formula 1 Design

–

High accuracy

• Daily comparison to wind tunnel tests available

–

Fast Turn-around

• Need to minimize CPU usage

DOE Studies

–

Optimizing multiple variables

–

Running 100’s of studies to look at drag reduction

–

Being used today for Trains, Trucks, Passenger Cars and Performance Vehicles

Recent Workshop:

–

“STAR-CCM+ CCM+ has pro roven en to be as accurat urate e as our ot

• ther in-hous
• use tools and easy

y to setup etup while e pro roviding g a much ch faster er overall rall turn-around time”

–

“CD CD-adapco apco idea of DOE licens nse e scheme me very appre recia ciated ed for design n optimi miza zation

• n

studies”

Vehic icle le Simulation mulation Compone ponent nts

14

Vehicle Aerodynamics

• Design Studies
• Aeroacoustics
• Water/Dirt Management

Vehi ehicle cle Aerod

• dynamics

ynamics News ws

Unsteady Aerodynamics

• When to use?

Reducing Turn-around Time

• Taking Advantage of Coupled Solver for reducing
• Automation

Water/Dirt Management

• New wall film model in STAR-CCM+ being used for water management

Accelerating erating Converge ergence: nce: Couple pled d Solv lver er

Coup uple le solver er has really ly been een pus ushed ed hard d over er the e past year ar by our ur F1 teams ms

– Latest testing shows significant gains for all vehicles

STAR AR-CC CCM+ M+ has some me feat atures s to help make runnin ing com

• mple

lex cases ses easier sier with h cou

• uple

le solv lver Expert initialization: Grid sequencing

• CFL value should be similar to target CFL (120-

200)

Expert Driver: Intelligent system which makes it easier to run with high CFL value AMG Acceleration: Bi Conjugate Gradient Stabilized

• Improves rate of convergence.

Couple: 6 Yaw Segregated: 6 Yaw Couple: 0 Yaw Segregated: 0 Yaw

7.67 13.36 2.22 5.29

Elapsed Time (Hours)

64 Cores

Couple: Grid 2 Segregated: Grid 2 Segregated: Grid 1

2.7 9.5 11.3

Elapsed Time (Hours)

64 Cores

In 2012, we are investigating improvements to extend coupled solver to the vehicle thermal management

Vehic icle le Simulation mulation Compone ponent nts

16

Vehicle Aerodynamics

• Design Studies
• Aeroacoustics
• Water/Dirt Management

Vehi ehicle cle Aerod

• dynamics

ynamics News ws Water/Dirt Management

• Rain management and soiling affect the safety, handling and aesthetics of

passenger vehicles.

WATER ER DEPOSITION POSITION

Modeling deling Rain in Water ter/Mist Mist:

• Lagrang

grangian ian droplet

• plet model,

del, active ive or froz

• zen

en gas as fie ield ld

• Low

w comp mput utat ation ional al cos

• sts

ts

• Genera

nerally lly Freeze eeze flo low fie ield ld

• Define

ine mass/ ss/pa particle rticle siz ize

• Eule

lerian rian Multi lti-Phas Phase

• Can

n seed ed flo low fie ield ld with ith rang nge e of part rticle icle siz izes es

Courtesy tesy M. Islam, am, Audi AG

Water er Managem ement nt: : Wall Film lm Model

Capturin uring g ful ull affects cts of water er managem agemen ent: t:

– Aerodynamics field for vehicle, – Lagrangian-Eulerian two-phase and coupled particle tracking of discrete particles in an airflow continuum, – liquid-film formation due to impingement

• f droplets on the surface, resulting

liquid-film transportation, – and droplet stripping (re-entrainment) back into the continuum airflow due to edge effects of film instability.

Sample: ple: Side e Window Soiling iling

Plott tting ing Results sults

Add dd two scala lar r di displ player ers: For the e dr dropl plets ts sel elec ect t as “Part” the “Water” Lagr grangi gian Phase e and d “Velocity Magnitude” as the e scalar. For the e Fl Flui uid d Fi Film sel elec ect t as “Part” the desired shells and “Fluid Film Thickness” as scalar.

Simulating mulating Wiper er Motion

• n

Wall Fi Film Influenc ence e by win inds dshie ield d wip iper er

– Part of the design of the A-Pillar is influenced by flow pushed by the windshield wiper blades

Note: v7.04, expanding wall film for multi-component evaporation and

• condensation. This is a needed feature for SRC (Selective Reduction

Catalyst) simulations for users to migrate applications from Star-Cd

Vehic icle le Simulation mulation Compone ponent nts

22

Vehicle Thermal Management Front End Cooling Component Temperature Prediction

Vehi ehicle cle Thermal ermal Manageme gement nt News ws

Reducing Turn-around Time

• Handling Complex Assemblies
• Indirect Mapped Interfaces
• Automation: Customizing STAR-CCM+ for seamless integration to PLM

Componen ponent t Temperat perature ures Surfac ace-2-Sur Surfac ace e Radiation ation

– Parallel View Factor Calculation – Using from 300,000 to over 1 million radiation patches

Tools ls for modeli eling g large rge CHT T models els

– PMLXML import to maintain CAD structure – Tools/Procedures for building part contacts – Thin mesher for sheet metal – Co-Simulation

• Allows separate model of solid

and fluid to be joined together during analysis.

Vehicle hicle Aerody

• dynamic

namics

Surfac ace e Remesher mesher

Geometry

• metry reten

ention ion (patch atch perimeter rimeter, cad d face e perimeter rimeter) Curvatur rvature alig ligned ed mes eshe hes s (if if cad d data a is is a availa ailable ble)

Inter erface ce type e for CHT analys yses es

– Allows for quick and reliable generation of non-conformal interfaces – Saves time at the surface preparation stage – Designs may be easily changed and analyzed

Leverages erages proven en CAE AE mapping ng technol chnology

• gy

Robu bust st, , high h qua uality y results ts for r non-con conformal rmal mesh eshes es

Indirect irect Mapped d Inter erfac aces es

New w eleme ement nt type e for modeli

• deling

ng thin n solids ids using “shell” elements

– Simulation of in plane thermal conduction – Single or multiple layers of shells

Shell ell region ions s aut utoma

• matical

tically ly creat ated ed on sur urface face parts

– New shell region and interfaces generated

STAR-CCM+ CM+ v7.02: Shell ll Modeli ling

Vehic icle le Therm rmal l Protection ection Sample ple of Fully y Conform

• rmal

al Grid

Solids lids Model l – Automatic

• matic Polyhedral

yhedral Meshing ing

Solids lids Model l – Heavy y use of Thin n Mesher er

Co Co-Sim

• Simulation:

ulation: Coupled pled Vehic icle le Therm rmal al Analysis ysis

Thermal Solution STAR-CCM+

Conduction + Radiation

Underhood Flow Solution STAR-CCM+

Air ir Side Side BC HT HTC, , Air ir Temp emp Me Metal T tal Temps emps

Solid Model

10-20 Million cells 2000-3000 Parts

Airstream Model

30-50 Million cells

Globa bal l Temper erat ature ure – Und Underbod erbody

Full Vehicle Thermal Management

Really used as a predictive tool. 30-40 Cases examined last year by our service group. Alternatively, can study local region for none problem

Temperat perature ure Monit itor

• r – Electrical

ctrical Harn rness ess

Peak Temperatures

Min/Max Temperatures are reported on all components

Temperat perature ure Monit itor

• r – Turboc
• charger

harger Heat at Shield eld

Heat Source

Conduction/convection and radiation are all broken out for each component

Vehic icle le Therm rmal l Managem gement nt: : Custom

• m Tools

ls

Designed to build simple/quick front end cooling studies. Targeting users of UH3D.

STAR AR-CC CCM+ M+ is cont ntinui inuing ng to grow w in the e aut utomo motiv tive e industr ustry

– Increase usage has pushed our development team to grow, and address new challenging issues – We are seeing improvements in speed, and reduction in turn-around time thru features such as the coupled solver – Wall film model is being used today to investigate vehicle soiling

• In 2012, added multi-phase will help with SRC simulations

– Thermal Heat Protection growing strong

• Producing highest quality models in the industry
• Continue to improved productivity of the engineers

Conclusion lusion

Wednesday morning presentations: 8:30 Fast simulation of body-in-white dipping 9:45 Customizing STAR-CCM+ for seamless Integration to PLM