In this work, continuous wave and nanosecond pulsed wave laser were considered for the modelling of the heat transfer and convective motion around Au nanoparticles suspended in water as illustrated in Figure . The equations (1 -3) and equation were solved separately using an FEM based numerical framework COMSOL Multiphysics 5.2. First, equation was solved in the frequency domain covering wide range of wavelength. The complex dielectric constants of Au for different wavelengths were obtained from Johnson and Christy . These values can be safely assumed constant within the temperature range of this study . The values of thermophysical properties used in this work are listed in Table 1 .