Understanding the interaction of particle clouds with detonations and explosions is vital to enhance safety in industries and to develop novel strategies for threat reduction. Although experimental investigations have been helpful, they are limited due to the destructive nature of the flow. Where experiments are lacking, numerical simulations have played a crucial role and are now an irreplaceable component in developing novel safety features. However, there are several challenges in modeling detonations in multiphase mixtures, especially when the particles form dense clusters. Accounting for all the particles in a flow is a difficult task and is computationally unfeasible in some cases. In this talk, a methodology developed to address these challenges and successfully simulate detonations and explosions in gas-particle mixtures is presented. The method utilizes a massively parallel Lagrangian approach coupled with an Eulerian gas-phase solver. In addition, the Lagrangian solver is also coupled with an Eulerian dispersed phase approach to resolve localized dense particle clusters. The developed multi-phase solver is employed to investigate the acceleration of deflagrations and the subsequent transition to a detonation in confined domains. Detonation interaction with inert particle clouds is also investigated with a focus on the critical mass of particles required for detonation suppression or quenching. Finally, evaporation of aqueous aerosol in post-detonation flow is analyzed, and the critical regions for optimal interaction of the aerosol cloud with the explosion are identified.