The irradiation effects are studied, of solid-state laser on four kinds of plates (three of them are made of metal, the other, of composite), in experiments characterized by relatively large laser spot and the presence of surface flow. The thick iron samples, thin aluminum samples and thin carbon fiber/epoxy resin samples are subjected to air or N2 surface flow, while the box-shaped samples, containing a thin aluminum plate irradiated by laser, are filled with water. It is found that, besides the common role in all four cases cooling the plate by convective heat transfer, the fluid plays other different roles in different case influencing the dynamic response of the plate. The roles of the fluid in each case are described either with analytical boundary conditions or with differential equations, which are then incorporated into computational models. Numerical simulations are carried out, with results compared with the experiment results to explain the irradiation effects.