Gaseous Flow Focusing I

We describe the geometries that produce the flow focusing effect and their applications. The forces, flow patterns, and instability mechanisms in the low-viscosity and viscous cases are discussed. We show results on the popular gas dynamic virtual nozzle (GDVN) geometry. Global stability analysis is used to gain insight into the axisymmetric and whipping instabilities limiting the applicability of this technique. Results of the microdripping mode are also presented.