MICADO

A1.Noise level at 500Hz: point source above a porous road.

MICADO is an acoustic software based of the Boundary Element Method (BEM). It is dedicated to precise outdoor sound propagation prediction (homogeneous atmosphere) including complex boundaries (barriers, buildings, trains,..) with rigid or absorbent conditions.  MICADO is mainly used to design and optimize innovative noise barriers either outdoor or indoor.
The BEM technique leads to the meshing of boundaries only which allows predictions to be made for large problems in 2D and 2.5D as is usually required for transport noise and human activity situations.

MICADO has several noticeable characteristics:

  • Elementary Functions (aka Green functions) which include part of the boundary
  • Optimized computation times (tabulated Hankel functions, optimized solver, adaptative meshing at each new frequency,…)
  • 2D, 2.5D and 3D versions : The 2.5D version allows the study of 2D geometries with point sources or incoherent line sources (traffic flow). The 3D version is employed for full geometries and leads to reference solutions.
  • « Multi-domain» module  allows to define porous media as equivalent fluids or simply to distinguish baflled and unbaffled domains.
  • « Periodic Formalism » module for the study of periodic situations where only a reference pattern is discretized thus reducing computation times.
  • Coupling with other software (tyre radiation, air pumping…)
  • Coupling with optimisation algorithms (genetic algorithms…)

Main applications of MICADO

In Environmental Acoustics :

  • Characterisation et optimisation of complex noise barriers (A3)
  • Roughness characterization (ground, facades, barriers, berms,…) (A4)
  • Propagation with periodic geometries –trees, louvres sonic crystals …) (A6)
  • Multi-domain propagation through asphalt or porous media (stones.) (A1,A3)

In Building Acoustics :

  • Propagation through facade openings (A5)
  • Propagation inside an open-space office (A2)
A2. Barrier between two desks inside an open-office. The ceiling and the floor are not descretized (10000 Hz).
A3. Noise map around a porous gabion wall (2000 Hz). Each stone is a different domain.
A4. Modification of the sound field in a street due to balconies.
A5. Sound transmitted through an air inlet with moving slats (500 Hz).
A6. Pressure map through a 30 m wide thicket along a road (500 Hz).
Only a 30x8 m2 central portion is meshed.

References :

  • P. JEAN (1998) Journal of sound and vibration 212, 275-294. A variational approach for the study of outdoor sound propagation and application to railway noise.
  • P. JEAN, G. DEFRANCE, Y. GABILLET (1999). Journal of Sound and Vibration 226(2), 201-216. The importance of source type on the assessment of noise barriers.
  • J. DEFRANCE and P. JEAN. (2003). Applied Acoustics.64, 765-780.  Integration of the efficiency of noise barrier caps in a 3D ray tracing method. Case of a T-shaped diffracting device..
  • M. BAULAC, J. DEFRANCE, P. JEAN (2007) J. Sound Vib. 300(1-2), 71-87   Optimization of multiple edge barriers with genetic algorithms coupled with a Nelder-Mead local search
  • M. BAULAC, J. DEFRANCE, P. JEAN – (2008) Applied Acoustics 69(4), 332-342 “Optimisation with genetic algorithm of the acoustic performance of T-shaped noise barriers with a reactive top surface”.
  • P.JEAN Euronoise 2006. Tampere, Finlande. A multi domain BEM approach. Application to outdoor sound propagation and tyre noise. 
  • P. JEAN, N. NOE, F. GAUDAIRE.  , (2008)  Acta Acustica united with Acustica 94(1) 1, pp. 91-103. Calculation of tyre noise radiation with a mixed approach.
  • P. JEAN SIA Le Mans 15-16 November 2006. F.CONTE, Tyre noise : road effects.
  • P. JEAN (2001). Acta Acustica 87, 236-246 Coupling geometrical and integral methods for indoor and outdoor sound propagation - validation examples.

[Translate to English:] Contacts

[Translate to English:] Philippe JEAN

Tél : +33 (0)4 76 76 25 14

Email : philippe.jean@remove-this.cstb.fr

 

Jérôme DEFRANCE

Tél : +33 (0)4 76 76 25 35

Email : jerome.defrance@remove-this.cstb.fr

 

Information sheet