Since a photon carries both energy and momentum, when it interacts with a particle,\nphoton-particle energy and momentum transfer occur, resulting in mechanical forces acting on the\nparticle. In this paper we report our theoretical study on the use of a laser beam to manipulate\nand control the flow of nanofluids in a micro-channel. We calculate the velocity induced by a laser\nbeam for TiO2, Fe2O3, Al2O3 MgO, and SiO2 nanoparticles with water as the base fluid. The particle\ndiameter is 50 nm and the laser beam is a 4 W continuous beam of 6 mm diameter and 532 nm\nwavelength. The results indicate that, as the particle moves, a significant volume of the surrounding\nwater (up to about 8 particle diameters away from the particle surface) is disturbed and dragged\nalong with the moving particle. The results also show the effect of the particle refractive index on the\nparticle velocity and the induced volume flow rate. The velocity and the volume flowrate induced by\nthe TiO2 nanoparticle (refractive index n = 2.82) are about 0.552 mm/s and 9.86 fL, respectively, while\nthose induced by SiO2 (n = 1.46) are only about 7.569 �¼m/s and 0.135, respectively.
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