This mini-symposium aims to showcase and discuss recent advancements in mesh reduction methods, specifically focusing on boundary element methods (BEM), mesh-free methods, and particle-based methods such as smoothed particle hydrodynamics (SPH) and discrete element methods (DEM). The primary objective is to address complex problems associated with multi-scale phenomena, multi-interaction scenarios, and the interaction between solids and fluids. The mini-symposium will cover a wide range of topics, including but not limited to hybrid approaches that combine BEM, mesh-free methods, particle-based methods, and molecular dynamics for multi-scale simulations. Sophisticated frameworks based on BEM for studies of the micro-mechanics of heterogeneous materials. Multi-scale couplings between BEM and other approximations such as molecular dynamics (MD) or coarse-grain models. Development and enhancement of SPH and DEM for modelling solid-fluid and fluid-fluid interactions, with a focus on high-strain morphology changes, soft materials and complex fluids. Mesh reduction techniques specifically designed for simulating multi-scale phenomena in coupled solid-fluid systems using molecular dynamics . Modelling multi-interaction scenarios involving particles, interfaces, and fluid-solid boundaries, particularly addressing fluid-fluid capillary interfaces and surface deformations. Parallel computing and optimisation techniques for accelerating simulations in mesh reduction methods, like in the BEM open source software. Also, in in-house developments on SPH and DEM, enabling efficient 3D modelling of different phenomena. Applications in various fields including, additive manufacturing, granular materials, bio-mechanics, microfluidics, and fluid dynamics. We invite researchers and practitioners actively working on these mentioned applications and methods to present their latest research findings at this mini-symposium. The aims are to provide a platform for meaningful discussions, exchange of ideas, and potential collaborations among experts in the field. Also, address challenges, explore novel methodologies for future developments.