In view of the existing literature, it appears that realistic studies for common shapes like nanosphere and nanorods with reasonable assumptions and consideration of diverse practical scenarios are still required to develop deeper insight . In this context, Au nanorods have interesting possibilities due to their spectral tunability as well as high absorption in a suitable size range. Also, the size effect on photothermal effect of Au nanospheres in a wide size range itself is an overlooked aspect . Thus, this study includes some important aspects of the heat transfer and convective fluid flow phenomena around nanoparticles in water medium irradiated by laser. In particular, the present study compares different configurations of nanospheres and nanorods under continuous wave and pulsed wave laser in order to analyse the fluid convection around the nanoparticles inside confinements of varying size subjected to slip/no-slip and constant temperature/adiabatic wall boundary conditions on the walls.