in the 1970s, thanks to new torque-converter developments with improved traction characteristics, (approaching the start-up traction) a two-converter transmission was designed to replace the previously used three-converter transmission. and even today, torque-converters are still being improved, although they have reached an advanced stage. modern computational fluid dynamics (cfd) can now provide engineers with detailed information on the flow-patterns inside a rotating turbine wheel. here, the oil-filled circuit in which the turbine turns is portrayed as computerized grid showing the flow characteristics at each grid intersection. for each of these points, the flow volume, speed, and pressure can be calculated. later during the analysis phase, a three dimensional model of the circuit's flow pattern can be viewed and flow disruptions which reduce the converter's efficiency can be identified, such as: eddies, surface turbulence and mis-directed fluid-flows along the turbine wheel. in addition, aside from visualizing these flow disruptions engineers can also use cfd to calculate the resultant loss in converter efficiency.