Advanced Sound Propagation Modeling in I-Simpa relies on leveraging its open-source 3D graphical user interface alongside its embedded core solver: the SPPS code (Simulation de la Propagation de Particules Sonores). SPPS uses a particle-tracing approach to model complex indoor, industrial, and outdoor acoustic fields.
Achieving accurate, high-utility results from I-Simpa requires understanding code optimization, advanced meshing, material constraints, and automation. 1. Optimize the Core Engine (Energetic vs. Random)
The SPPS engine allows you to select between two fundamentally different particle-tracking calculation methods. Choosing the right one balances execution speed and results precision:
Random Method (Fast Prototyping): In this mode, individual particle energy varies randomly based on the physical phenomena encountered at boundaries, keeping the overall particle count constant. Use this for initial geometry testing and setting up parameters.
Energetic Method (High Precision): Each particle carries a fixed energy unit (
). As collisions happen, particles are progressively absorbed and vanish, reducing the particle pool over time. Switch to this method for final, high-accuracy acoustic mapping, noting that it demands significantly more computational time. 2. Geometry Correction & Advanced Meshing
Unclean 3D CAD meshes (e.g., non-manifold geometry, open holes, or overlapping faces) will cause particle leakage and ruin the calculation.
Use Average Model Remesh: If your imported scene geometry is imperfect, utilize the Average Model Remesh feature during the file import phase.
Voxel Reconstruction: Setting the Model solving parameter to an optimal resolution (e.g., 6 or higher) will reconstruct the internal volume using a grid of 2n2 to the n-th power voxels, repairing gaps automatically.
Disable Pre-mesh Scene Correction: Once your geometry is repaired, uncheck Scene correction before meshing under the SPPS meshing tab. This prevents I-Simpa from recalculating repairs every time you rerun a mesh grid check. 3. Deploy Surface & Fitting Zone Constraints
For large-scale spaces or complex setups, use advanced spatial elements to save processing power while maintaining physics accuracy:
Surface Receiver Constraints: If you need micro-detailed sound maps on floors or walls, activate the Surface receivers constraint ( m2m squared
). This splits target surface receivers into finer sub-elements without forcing a global, system-wide mesh reduction.
Fitting Zones for Industrial Spaces: In large warehouses or halls packed with un-modeled machinery, avoid complex 3D rendering. Instead, create a Fitting Zone (a transparent 3D box) and apply probabilistic scattering parameters (mean free path, absorption, and diffusion laws) to mimic dense clutter. 4. Directivity & Temporal Tuning Newbie Information Request on How to Use I-SIMPA