where 𝑘 is the thermal conductivity of water, T is the temperature, Q is the heat source. We use Equations ( ) and (2) in the domains with and without laser (i.e., heat source), respectively. Next, the system for performing temperature calculations is illustrated in Fig. referred to as the sample chamber. Buoyancy-driven natural convection can interfere with thermophoresis observations when the water layer exceeds about 50 μm. Thermophoresis experiments typically use water layers between 1 and 20 μm. The 8 μm thickness in this study was chosen to match the conditions of subsequent experiments. Given the steady-state nature of the temperature field under consideration, the boundary conditions for temperature and heat flux at the interfaces were assumed to be continuous. Furthermore, the boundary conditions for the outer surfaces of the glass substrate and the water were set to room temperature, 25°C.