MIGRATION FROM STAR-CD TO STAR-CCM+ AT THE

BMW GROUP.

Dr. Lehmann, BMW Group, 21.03.2012

page 2

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. AGENDA.

• Motivation

• Overview: CFD at the BMW Group

• STAR-CCM+ Migration Project

• Project Aim

• Project Structure

• Project Results

• Conclusion and Outlook

STAR Global Conference,19 -21.03.2012

• Increasing number of models

• No physical prototypes (early phase)

• Increasing regulatory requirements

• Reduced development time

development process – „old“

development process – „new“

time

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. MOTIVATION.

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IT Recruiting Tag, L5-9, 20.09.2011 page 4

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. OVERVIEW: CFD AT THE BMW GROUP.

HVAC

Internal Combustion

external Aerodynamics

Thermal Management

Brake Cooling

Engine Cooling

Participation in the

STAR-CCM+ software migration project

Light Systems

Aeroacoustics

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. PROJECT AIM.

• Ability to use STAR-CCM+ for full vehicle simulation

• Time- and cost savings compared to the STAR-CD process:

• faster geometry preparation through surface wrapping

• process automation (Pre- and Post-Processing)

• standardized modeling guidelines

• comprehensive data management

• less calculation time

• better accuracy

• avoidance of co-simulation (radiation)

• Quality improvement through the implementation of consistent,

integrated and comprehensive methods and processes

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MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. COMPARISON OF CURRENT AND TARGET PROCESS.

Pre-Processing

Case Setup

Solving

Post-Processing

CAD-Geometry

Boundary- conditions

Derivation of Variant

Automation

Surface Wrapping

Automation

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Automation

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. ESTIMATED TIME SAVINGS.

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~50 %

Estimation (before the project): Possible time saving per simulation model up to 50 %

time

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. PROJECT STRUCTURE + COOPERATION.

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Process, Methods and IT

Thermal Management Aerodynamics Engine Cooling Brake Cooling

ISV

^

Geometry Preparation STAR-CCM+-Jour Fixe Migration Meeting

• BMW: every week in 2010/2011

• CD-adapco: once a month in 2010/2011

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. KEY RESULTS.

Pre-Processing

Case Setup

Solving

Post-Processing

CAD-Geometry

Boundary- conditions

Derivation of variants

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• Best Practices for:

• automation + java-scripting - done

• efficient full vehicle modeling + part exchange - done

• derivation of sub models + data mapping - done

• radiation methodology - in progress

• fan modeling - in progress

• BMW enhancement requests through LOP-List:

• liquid-film model

• CAD-reader

• enhanced functions for

model structuring

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. SUPPORT BY CD-ADAPCO.

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MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. ACHIEVED TIME SAVINGS.

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Result (End 2011): Time saving per simulation model up to 40 % compared to STAR-CD process

~50 % ~40 %

time

• Conclusion

• migration project successfully completed (end of 2011)

• numerous models (>50) successfully evaluated

• TCO reduced (DMU 2.0, surface-wrapping, infiniband,

java-automation,…)

• fall back solution for STAR-CD: POD

• good cooperation with CD-adapco established

• good cooperation within BMW departments established

• Outlook

• radiation/fan methodology – CD-adapco/BMW

• further automation post-processing – BMW

• adoption of simulation data management (SDM) – BMW

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. CONCLUSION + OUTLOOK.

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Thank you for your attention!

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. KEY RESULTS – DERIVATION OF CAD-DATA.

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• Current Situation

• Linux-shell-scripts to derivate geometry data for

full vehicle CFD-model out of CAD-System

• Problems

• process velocity + stability (e .g. new CAD-system-release)

• no user support + no maintenance

• Proposed Solution

• Fully automated, standardized and supported process

using DMU-Client 2.0 of CAE-Bench (BMW SDM Application)

• Result

• Productive use in the STAR-CCM+ process, today 20 users (increasing)

• Saving of time: several h per full vehicle model

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. KEY RESULTS – CONSISTENT NAMING CONVENTION.

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naming convention CFD full vehicle models

File structure Folder Fxx_Nxx_Hx_Lx_xx_Vxx_Basis_Mustermann_100111<-- Bearbeitungsdatum DA

Subfolder Exx Axx … … Information … Data structure Exx Fxx_Axx_lx.nxx Fxx_Axx_rx.nxx Fxx_Sxx_Axx.nxx Fxx_Sxx_lx.nxx

… … Axx Fxx_Nxx_Hx_Lx_Mx.nxx Fxx_Nxx_Hx_Lx_Gx.nxx … …

Result: Consistent naming convention is precondition for the comprehensive use of automation scripts

STAR Global Conference,19-21.03.2012

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. KEY RESULTS – AUTOMATED CASE SETUP.

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• Automation using Excel-tabulars + Java-macros (CD-adapco Training + Best Practice)

• Use Cases:

• general simulation parameter (solver,…)

• cooling module (head curves, fan rpm,…)

• material characteristics

• model structuring (level of detail per use case)

• Result: saving of time several h per full vehicle model

MIGRATION FROM STAR-CD TO STAR-CCM+ AT BMW. KEY RESULT - SWITCH TO INFINIBAND-HARDWARE.

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Result: Explicit reduction of calculation time

reasonable scaling for BMW full vehicle process