Discussion: “Three-Dimensional Vortex Method for Gas-Particle Two-Phase Compound Round Jet” (Uchiyama, T., and Fukase, A., 2005, ASME J. Fluids Eng., 127, pp. 32–40)

The paper by Uchiyama and Fukase 1 proposes a threedimensional vortex method for particulate flows, which is applied to a circular jet of air laden with glass particles. The numerical method presented has the following characteristics: 1 it includes the two-way coupling of the particles and the fluid, 2 it discretizes the vorticity in the gas phase in the usual manner when vortex blob methods are used, and 3 it accounts for the effects of viscosity in the fluid by means of the less-than-usual core spreading method. The method presented in the paper under discussion is claimed to be a 3D extension of the two-dimensional vortex method for particle-laden flows proposed by Uchiyama and Naruse 2 . Upon reading this previous work, however, one notes important differences in the core spreading viscous scheme. There is an apparent inconsistency in the paper in relation to the implementation of the vortex method, which will be discussed below. There are three issues that should be made clear.