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Free Field Technologies

HPC usage on acoustics modeling

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Agenda

  Free Field Technologies Overview

  Current required HPC ressources around some aeronautic applications

  New challenges for HPC ressources & PRACE response

  Conclusions

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  Free Field Technologies Overview

  Current required HPC ressources around some aeronautic applications

  New challenges for HPC ressources & PRACE response

  Conclusions

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Free Field Technologies

  Free Field Technologies is the leader in CAE:   Acoustics   Vibro-acoustics   Aero-acoustics

  The company has three main activities:   Development of the ACTRAN software suite   Provision of related services:

training, consulting, technology transfer, methodology development, installation and performance tuning, custom developments, CAE process automation

  Research in acoustic CAE and related fields

  Free Field Technologies operates from:   Mont-Saint-Guibert near Brussels (Headquarters)   Toulouse   Tokyo

  ACTRAN is used by over 200 industrial customers worldwide.

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  Based on Finite Elements Method:   Structure Modelling   Acoustic Modelling   Flow Effect   Coupling Effect   …

  Each element is defined by a list of nodes, representing the unknowns or Degree of Freedom (DOF)

  Each element is defined by physical properties

  The element size depends on the computed frequency and material properties

  The Assembly of the elements represents the problem to solve

The ACTRAN Technology

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  Solve an algebraic linear system (complex, unsymmetric) for each frequency in Three Steps:   Assemble the matrix system: Zx = B   Factorize the Z matrix: Z = LU (LU Decomposition)   Compute the x response of the system (vector)

  Size Systems to solve can be up to 3 Millions unknowns

The ACTRAN Technology

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The ACTRAN software suite

ACTRAN Vibro-Acoustics ACTRAN Aero-Acoustics ACTRAN TM

ACTRAN Acoustics

ACTRAN DGM

ACTR

AN V

I

ACTRAN for NASTRAN

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  Free Field Technologies Overview

  Current required HPC ressources around some aeronautic applications

  New challenges for HPC ressources & PRACE response

  Conclusions

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Nacelle Intake Applications"

  Fan noise is the dominant noise source of modern high-bypass ratio turbofans"

  Prototyping: expensive & time consuming"  Required attributes for a simulation tool"

  Includes effect of heterogeneous mean flow"  Liner modeling"  Coupling with duct modes"  Frequency domain"

Acoustic lining

Modal Coupling

"nacelle" problem

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Nacelle intake Modeling"

  From 2D Modelling -> 3D Modelling to compute acoustic radiation"

  Fast Computation for 2D models but some approximations remains"

  3D models are accurates but limited for high frequencies."

Axisymmetric model (the back of the nacelle is not modeled)

A380 Nacelle

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Nacelle intake – HPC ressources"

  2D Modelling – Frequency 5 KHz – 760 KDOF - AIX/Power5 Cluster"

  3D Modelling – Frequency 1 KHz – 3 MDOF - AIX/Power5 Cluster"

  Efficient parallel computing method on a limited number of processors"

  Each node requires a large amount of memory"

2D RAM

Solver (Gb)

RAM Total (Gb) Factorization

time (s) Total

time (s)

1 proc - ic 3 7 88 35000

15 procs – ic 3 7 88 2863

Nacelle RAM

Solver (Gb)

RAM Total (Gb)

Space Disk Used (Gb)

I/O time (s)

I/O data (GB)

Factorization time

Total time

1 proc - ooc 23.6 34.8 200.6 26074 2408.2 24h24mn 34h18mn

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Exhaust Noise Applications"

  Turbo machinery noise radiating from the bypass and core nozzles is becoming an important noise source on modern aircrafts"

  Prototyping: expensive & time consuming"

  Required attributes for a simulation tool"  Non-uniform and Rotational mean flow "  Thick shear layers and thermal gradients"  Liner modeling"  Coupling with duct modes"  Time Domain"

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Exhaust Noise Modeling"

  From 2D Modelling -> 3D Modelling to compute acoustic radiation"

  Linearized Euler Equations (LEE)   DGM scheme in the time domain   Adaptative element order(1 to 16)

3D Mesh 2D Axisymmetric Mesh

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Exhaust Noise – HPC ressources"

  2D Modelling – Freq. 1 KHz – 2060 Elements – Linux Opteron Cluster"

  3D Modelling – Freq. 1 KHz – 440 000 Elements – Linux Opteron Cluster"

  Efficient parallel computing method on a large number of Processors"

  Each node requires a small amount of memory"

2D RAM Solver (Mb) Computation time

48 procs 340 24 mn

3D RAM Solver (Mb) Computation time

56 procs 4600 45h

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  Free Field Technologies Overview

  Current required HPC ressources around some aeronautic applications

  New challenges for HPC ressources & PRACE response

  Conclusions

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3D Modelling : the high frequencies challenge"

  For 3D Modelling, the model size is:"  frequency dependant "  " follow a cubic law."

  Reach Higher Frequencies require:"  Robust Graphical User Interface for

models building"  Strong scalability for HPC usage"  Huge HPC Ressources at affordable

price"

Acoustic field © Aermacchi

0  25  50  75  100  125  150  175  200  

1000   2000   3000   4000   5000   6000  

Factor  on  mod

el  size  

Frequency  (Hz)  

3D  Model  size  factor  

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The PRACE Project"

  For the Small CAE Software Enterprise"  Access to a large number of platform for testing new development in HPC"  Reproduce the HPC environment of our Tier-1 Company"  Promote HPC for our customers & prospects"

  For the R&D acoustics Department in SME"  Increase their CAE activity in reducing HPC costs"  Reduce their licensing costs via a pay per use activity"  Improve the quality of their products by a better acoustic prediction"

  Confidentiality data must be guarantee on remote servers"

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Some Automotive Customers

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Some Aerospace Customers

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Some Other References