The fluid flow in thermal ink-jet transducers is highly dynamic in the sense that at no time during its operation does the flow reach a steady-state condition. The transient flow is affected by the inertial and viscous effects. These two effects are reflected through the inertance and resistance parameters of the transducer geometry. In this study we present a general background on the inertance and resistance parameters, present a method for calculating these parameters for a given three-dimensional geometry, and briefly outline their role in the ink drop ejection process.