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Cluster configuration for 3D simulation of acoustic transducer and wave - guide

Cluster configuration for 3D simulation of acoustic transducer and wave - guide. Sylvain Ballandras, William Daniau Institut FEMTO-ST Département de Physique et Métrologie des Oscillateurs, Besançon, France. Summary of the talk. FEMTO-ST (brief presentation)

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Cluster configuration for 3D simulation of acoustic transducer and wave - guide

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  1. Cluster configuration for 3D simulation of acoustic transducer and wave-guide Sylvain Ballandras, William Daniau Institut FEMTO-ST Département de Physique et Métrologie des Oscillateurs, Besançon, France 3rd BFG Workshop, Rechenzentrum Freiburg

  2. Summary of the talk • FEMTO-ST (brief presentation) • Simulation of acoustic transducers • Historical progression • The new cluster configuration • Some examples of application • Perspectives 3rd BFG Workshop, Rechenzentrum Freiburg

  3. FEMTO-ST Institute A new Research Unit 19 April 2007 Freiburg 3rd BFG Workshop 3rd BFG Workshop, Rechenzentrum Freiburg

  4. FEMTO-ST components • CREST Thermic, flow • LCEP Quartz technology • LMARC Mechanics • LOPMD Optics • LPMO Micro-systems, TimeFrequency FEMTO-ST = « Franche-comté Electronique Mécanique Thermique et Optique - Sciences et Technologies» 3rd BFG Workshop, Rechenzentrum Freiburg

  5. FEMTO’s Technology center : MIMENTO • 3D Microfabrication Isotropic and Anisotropic chemical etchning, DRIE, LIGA • Microfabrication on piezoelectric materialsQuartz, LiNbO3, Piezocomposites, AlN • Hybrid Micro-mechanics Silicon technologies dedicated to MEMS • Nanotechnologies FIB etching, e-beam lithography, porous silicon, auto-assembling sinlge layers • 370 m2 dedicated to clean room • 230 m2 for chemics and back-end • 7 M€ of technological equipments • 18 engineers and techicians 3rd BFG Workshop, Rechenzentrum Freiburg

  6. Simulation of acoustic transducersDifferent kinds of transducers considered in these works • Surface Acoustic Wave devices • Source, filters, sensors • Thin Film Bulk Acoutic Resonator • filters and sensors • Piezocomposite transducers • Imaging and non destructive control • Micomachined Ultrasound Transducers • Imaging and sensors 3rd BFG Workshop, Rechenzentrum Freiburg

  7. Piezoelectric substrate Sampled impulse response (Quartz, LiNbO3, LiTaO3, ...) SAW Transducteurs Interdigitatés 100 MHz 500 MHz 1 GHz 2 GHz Elementary structure of a SAW Bandpass filter Overlap shape of the fingers = Fourier trasform of the expected spectral function 10 µm 2 µm 1 µm 0.5 µm Electrode width Operating frequency 3rd BFG Workshop, Rechenzentrum Freiburg

  8. Series structure AlN Pt Si SiO2 Thick SOITM wafer Film Bulk Acoustic Resonators Bragg mirror Air or vacuum gap (surface micro-machining) Piezolayer excited using 2 electrodes Si substrate Si substrate Si membrane HBAR for frequency source application fr = 2.497 GHz, Ks² ~1‰,Q = 2210 3rd BFG Workshop, Rechenzentrum Freiburg

  9. Principle of MUTs Implementation of piezoelectric MUTs Simulation of a capacitive MUT 3rd BFG Workshop, Rechenzentrum Freiburg

  10. Multichannel acoustic probe Reflected waves Transmittedwaves Emitted acoustic beam Toward the processing unit Beam forming by phase construction Fluid medium exhibiting various acoustic impedance areas General principle of an acoustic imaging system 3rd BFG Workshop, Rechenzentrum Freiburg

  11. Mathematical problem :Opa’s Physics Hooke’s law Electrical induction Linear but anisotropic, layered, piezoelectric materials with periodic inhomogeneous excitation Newton’s law Poisson’s law 3rd BFG Workshop, Rechenzentrum Freiburg

  12. Need for Intensive Computation • Design : choice of the right parameters for the considered application • Temperature stability, coupling factor, figures of merit,…  Requires numerous fast computations • Analysis : understanding the actual operation of the device • Assessment, deviation, model updating…  Requires large model implementation 3rd BFG Workshop, Rechenzentrum Freiburg

  13. A B Radiation conditions Meshed region Transducer x2 x1 x3 Nature of the implemented models Finite Element Analysis Boundary integrals or elements 3rd BFG Workshop, Rechenzentrum Freiburg

  14. Definition of the Green’s function The Green’s function defines the linear relation between mechanical displacement and surface stresses 3rd BFG Workshop, Rechenzentrum Freiburg

  15. Spectral relations Fourier transform along t s is the slowness defined as s=/k (no dispersion assumed) Fourier transform along x Piezoelectric, layered problems : only is easily accessible 3rd BFG Workshop, Rechenzentrum Freiburg

  16. FEA : 3D requires large algebraic systems to be solved BEM : convolution techniques impose all the dof are connected one to another Main modeling constraints 20 nodes cubic element 4 dof/node  Elementary matrices : Mass, Stifness 3240 complex*16 each No radiation With radiation 3rd BFG Workshop, Rechenzentrum Freiburg

  17. How to address the problem • Operation in harmonic conditions • No time dependent variables • No Fourier transform • Computation of the solution for each frequency point • Periodic boundary conditions • Applicable in harmonic and time domains as well • Access to mutual terms require Fourier transform • Enlarge the matrix profile • Absorbing conditions for simulation of non periodic problems 3rd BFG Workshop, Rechenzentrum Freiburg

  18. Computation conditions Mutual terms deduced from the harmonic analysis Harmonic excitation Harmonic impedance 3rd BFG Workshop, Rechenzentrum Freiburg

  19. Typical example of harmonic to mutual transformation Fourier transform Sommerfeld integral convolution Harmonic domain Mutual parameters Real space simulation 3rd BFG Workshop, Rechenzentrum Freiburg

  20. Some history…of a small physicist team using computers • Paleonthology : from µVAX (1MB RAM) and APPOLO Stations (8 MB RAM) to HP700 Workstations (64 MB RAM – 25 k€/machine) • 1995 : a Power Challenge machine @ LMARC Besançon (500 kF ~ 75k€) These approaches were expensive and did not provide very large computation capabilities 3rd BFG Workshop, Rechenzentrum Freiburg

  21. 1998 : A new cluster approach • Price reduction of personal computer together with Pentium-CPUs availability  Increase of the PC park in labs • Arising of libraries dedicated to cluster parallel processing for stand-alone machines • Parallel Virtual Machine – PVM • MOSIX + OpenMOSIX Requires high data flow rate network connection : 100 Mbit/s to 1Gbit/s 3rd BFG Workshop, Rechenzentrum Freiburg

  22. 2005 : Return of the SMPs • New SMP machines available • Price reduction • 64-bit-CPU • Large RAM access and handling (larger than 4 GBytes) • These machines can deal with • Numerous « small » computations • Large model implementation For a moderate price (20 to 40 k€), One can access intensive computation units 3rd BFG Workshop, Rechenzentrum Freiburg

  23. Calculation unit : Computer Coorp. • 8 AMD Opteron DUAL CORE CPUs 875 – 2,2 GHz • Mother Card chipset Nvidia NForce Pro 2200 & AMD 8131 • 128 GByte DDR PC3200 ECC Registered • Two connectors PCI Express 16x • Integrated grphic interface ATI Rage XL 8 MO • Dual Interface Lan Gigabit 1000 BT, RJ45 connect. • 2 x Hard Disks SATA Raptor 74 Go – 10 000 tr/min (RAID 1 System) 3rd BFG Workshop, Rechenzentrum Freiburg

  24. Operating system Linux x86_64 Distribution under GPL licence basedonthe RedHatEnterprise 4.0, Upgraded, Optimised core (http://www.centos.org/) Miscellaneous Managing the grappe Ressource statistics Advanced parallel tools 3rd BFG Workshop, Rechenzentrum Freiburg

  25. Programmation : Fortan 95 Protland • 2 simultaneous compilation licence with : • BLAS (Basic Linear Algebra Subprogs) • LAPACK (Linear Algebra Package) • FFTW (Fast Fourier Transform) • This compiler support OpenMPI chosen for code parallelisation • Parallel library : MPICH, LAM/MPI, PVM (on demand) Optimized for AMD64 3rd BFG Workshop, Rechenzentrum Freiburg

  26. General outlook of the system distributed by 3rd BFG Workshop, Rechenzentrum Freiburg

  27. SMP versus distributed machine cluster • SMP is built once, poorly oriented to updating • SMP can handle large memory resource at once (the equivalent to our system is 8 machines with 16 GB RAM) • Due to technological improvements, SMP are dedicated to be overcome • For addressing large 3D problems, SMP is well adapted to our demand because of large RAM handling 3rd BFG Workshop, Rechenzentrum Freiburg

  28. How do we use parallel capabilities of the SMP • Quite rustically at this time : split of the wave-number and frequency ranges in 16 small parts launched on the SMP CPUs  rebuild of the final result as a unique data set • Real parallel computation (i.e. programming) investigated for large 3D models and time dependant problems 3rd BFG Workshop, Rechenzentrum Freiburg

  29. Some examples of applications 3rd BFG Workshop, Rechenzentrum Freiburg

  30. 3D SAW modeling Rayleigh wave on quartz (YX) p=20µm, w=5 3rd BFG Workshop, Rechenzentrum Freiburg

  31. pMUT in 2D-periodic time domain Top Silicon plate PZT Silica spacer PZT is excited by a 1V.Dirac voltage Silicon base The Silicon base is clamped 3rd BFG Workshop, Rechenzentrum Freiburg

  32. pMUT Simulation results : Harmonic vibration and mutual coupling Different phase excitations along x, In-phase excitation along y 3rd BFG Workshop, Rechenzentrum Freiburg

  33. CMUT with Hexagonal periodicity In phase Fundamental In phase S1 mode Phase /4 Antisym. In phase 2nd Harm. 3rd BFG Workshop, Rechenzentrum Freiburg

  34. CMUT Experimental response Simulation results (3D) 3rd BFG Workshop, Rechenzentrum Freiburg

  35. Conclusion • Acoustics requires systematic computation tools for design and analysis as well • SMP machines can nowadays answer small scientific group demands for moderate (accessible) prices but… • 64-bit CPU allows for large RAM resource managing well-suited for 3D computation • There is still some distance for our industrial partners to share facilities and computation resource…but… 3rd BFG Workshop, Rechenzentrum Freiburg

  36. Perspectives with SMP capabilities • Simulation of whole transducer structures for imaging probes and image simulation • Accounting for parasitic effects in 3D simulation of elastic wave-guides ultimate signal processing devices • Non-linear periodic time domain simulations (with acoustic radiation effects) • Actual behavior of acoustic sensors in organic environments • Optimization of finite dimension devices using the harmonic approach combined with PMLs 3rd BFG Workshop, Rechenzentrum Freiburg

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