t will be slightly greater based upon the chosen angle u03b8 2 the diffuser divergence angle may be preserved from the baseline further experimental variations may refine such ejector or configuration for example it has been determined that d min may be modified to be slightly less than the diameter of the baseline straight mixing portion for example it may be 95 100 of the baseline diameter more narrowly 98 99 in distinction d t may be slightly greater than the baseline diameter e g 101 110 more narrowly 102 104 alternatively or additionally a computational fluid dynamics cfd program may be used to model ejector performance while the various parameters are varied for example as discussed above fig4 shows an ejector having such a slight divergence in the mixing section 206 by way of contrast fig5 shows a similar plot for a baseline ejector the simulated conditions involve a slight off design operation in baseline nominal operating conditions the efficiencies of the prior art and fig3 ejectors are both 48 with an off design condition of slightly higher flow the baseline prior art ejector drops to 39 estimated efficiency whereas the ejector of fig3 retains 44 efficiency as an alternative variation fig6 shows an ejector 300 having a continuously curving longitudinal profile downstream of the minimum diameter location 310 to conveniently reference the longitudinal axial positions of various locations to compare with the fig3 embodiment one possible reference is to use the motive nozzle exit as the origin of a z axis pointing centrally downstream thus this arbitrarily defines z 0 u2261 0 a location of the minimum mixer cross sectional area or the beginning of any straight zone at.