Seismic wavefield simulation and characteristic analysis of marine fluid-solid coupling media based on mesoscopic kinetic theory

In marine seismic exploration, seawater and submarine strata constitute a typical fluid-solid coupling medium. Seismic wave propagation is accompanied by complex reflection, transmission, and wave-mode conversion. Traditional macroscopic numerical methods have certain limitations in interface processing and wavefield fidelity, which tend to introduce numerical errors and cause numerical dispersion. Based on mesoscopic kinetic theory, this paper develops a lattice Boltzmann-lattice spring (LBM-LSM) coupled method for seismic wavefield modeling in marine fluid-solid coupling models. The method adopts a unified grid and space-time synchronization mechanism, and realizes two-way fluid-solid coupling through interface momentum exchange, strictly satisfying the dynamic continuity condition at the interface. Numerical tests are carried out on two-layer and four-layer marine geological models and verified by comparison with the finite difference method (FDM). The results show that the proposed method is in good agreement with the traditional method in wavefield morphology and propagation travel time, with higher modeling accuracy, and can effectively suppress numerical dispersion and dissipation, leading to better wavefield fidelity. The method adopts unified grid iteration and is convenient for parallel expansion. It can clearly characterize direct waves, reflected waves, and transmitted waves, and accurately identify various wave types. This method characterizes seismic wave propagation more realistically from the mesoscopic scale, providing a new high-precision tool for marine seismic forward modeling, stratigraphic identification, and marine engineering geological evaluation.