Fig. 3.

(a) Simulation of the flow velocities and flow vectors of the fluid as it moved from the input channel into the detection zone (units are m s⁻¹). The simulation was run using Fluent software with quad element meshing and 80,000 nodes performed in Gambit. An outline of the probe volume as determined from Fig. 2(b) is shown as well (black dotted line). (b) 3D surface plot of the detection zone versus the irradiance experienced by single fluorescent entities as they traverse through the probe volume. The irradiance decreased as the beam expanded and thus, single fluorescent entities traveling along the edges of the Gaussian intensity profile show reduced photon fluxes.