Random walk dispersion model for missile exhaust smoke particles based on geometric topology and wall constraint effects

The dispersion of exhaust smoke particles generated during missile ignition is strongly affected by geometric confinement from launch platforms, leading to persistent smoke accumulation in the launch area, which poses significant challenges for visibility control and target detection. However, existing Random Walk Model (RWM) typically rely on simplified assumptions such as free-space domains or regular boundary geometries, limiting their applicability to complex wall-constrained scenarios. To fill this gap, a Geometric Topology and Wall-Constrained Random Walk Model (GTWC-RWM) is developed to simulate particle transport in complex launch-site environments. The model incorporates wall effects—including reflection, slip, and adsorption—through ray–triangle intersection methods for collision detection. Collision response parameters are expressed as second-order polynomials of incidence angle and calibrated using experimental data to ensure physical consistency. Validation against reference data and geometric obstacle scenarios confirms the model's predictive capability, yielding a maximum relative error of less than 26.16 %. Simulations reveal that wall-constrained effects significantly impede dispersion, with concentration gradients reaching up to 58.79 % between obstructed and unobstructed regions. A sensitivity analysis quantifies the influence of key parameters on near-wall concentration distributions.