Drop formation by DOD ink-jet nozzles: A comparison of experiment and numerical simulation

This paper presents a comparison of a numerical simulation of drop formation and ejection from a drop-on-demand (DOD) ink-jet nozzle with experimental observations from a particular nozzle-transducer design. In the numerical simulation, first the pressure waves in the transducer chamber are calculated using inviscid compressible flow theory to obtain the pressure history at the inner face of the nozzle plate. Then a viscous momentum integral computation is applied to the nozzle to obtain the velocity history at the outer face of the nozzle plate. Finally, the free surface shape is calculated using finite-difference methods on the one-dimensional equations for an inviscid incompressible free jet with surface tension that uses the nozzle exit velocity history as the driving boundary condition. The computations are compared with drop formation photographs obtained from a particular nozzle-transducer design. Encouraging agreement is obtained, but the numerical model will require added sophistication before detailed agreement can be expected.