What are the key dimensionless numbers used in convection heat transfer?

Key dimensionless numbers include: Reynolds number (Re = ρVL/μ) - ratio of inertial to viscous forces, determines flow regime; Nusselt number (Nu = hL/k) - ratio of convective to conductive heat transfer; Prandtl number (Pr = μCp/k) - ratio of momentum to thermal diffusivity, a fluid property; Grashof number (Gr = gβΔTL³/ν²) - ratio of buoyancy to viscous forces in natural convection. These numbers enable correlation of experimental data and scaling of heat transfer results across different conditions.