Numerical analyses of the conjugate heat transfer between freely moving, cold, and solid particles and a hot carrier fluid are performed. The numerical method is based on the coupled solution of the Navier-Stokes equations for the carrier flow and the heat conduction equation within the solid particles [1]. The particle surface is sharply resolved using an immersed boundary method with a cut-cell formulation. Simulations are conducted for O(1000) cold particles of ellipsoidal and spherical shape embedded in a hot and turbulent carrier flow. The fluid flow and the enthalpy equation in the particles is solved based on hierarchical Cartesian meshes coupled over a joint base level mesh. Results are presented for the heat transfer, the particle temperature distributions and the impact of the cold particles on the carrier fluid [2]. Additionally, a coupling approach also based on Cartesian mesh systems is presented for a gas/liquid multiphase flow. In this case, two individual lattice Boltzmann solvers are used for the liquid and gas phase, and a level-set solver is used to track the interface. The two solvers are coupled over appropriate interface conditions taking into account the surface tension [3]. This approach allows to sharply resolve the interface and to predict large densty differences without arbitrary forcing terms. The two coupling approaches are described in detail and results are presented for cold particles in a turbulent hot carrier jet and rising bubbles in a liquid. [1] Kiwitt, T., Meinke, M., Schröder, W., An efficient method to determine conjugate heat transfer in moving bodies on parallel computing systems, Physics of Fluids, Vol. 37, No. 063352, 2025. [2] Kiwitt, T., Meinke, M., Krug, D, Schröder, W., Direct particle–fluid simulation of spherical and ellipsoidal particles in turbulent pipe-free-jet flow, International journal of multiphase flow, 194, 2026. [3] Vorspohl, J, Peng, Y. Meinke, M., Krug, D., Schröder, W. Coupled Level-Set Lattice Boltzmann Method on Adaptive Cartesian Grids, arXiv:2601.05936, https://doi.org/10.48550/arXiv.2601.05936, 2026.