Jetting with solid impurities

The formation of liquid jets is key to a number of applications, and most notably the formation of ink droplets in inkjet printing technology. Here we study how the presence of a small solid and mobile inclusion within the nozzle can lead to distortion of the jetting patterns. In order to be able to efficiently and accurately model the whole jetting process we employ a D3Q27 enhanced color gradient lattice Boltzmann method and we couple it with the momentum exchange bounce back technique in order to resolve the fluid-structure coupling between the solid particle and the fluid, including the wetting condition of the surface of the particle. With the present method we are able to reach realistic density ratios and viscosity values, thereby allowing for a side-by-side comparison with experiments. A number of numerical simulations were conducted by varying the shape, size, density, initial position and orientation of the particle inside the nozzle, in order to study the effects on the shape and speed of the jetting liquid.