Computer simulation of three-dimensional transport during moistened defatted soy flour processing in the metering section of a single-screw extruder

A quasi-three-dimensional steady state finite-volume-based computer model for a power-law fluid is used to describe the three-dimensional transport during the processing of defatted soy flour with 25, 28 and 33 per cent moisture contents by weight in the metering section of a single-screw extruder. The numerical results have been compared with the earlier experimental results of Fong. The results are found to be reliable only for the highest moisture content dough (33 per cent by weight). The conclusion is that the quasi-three-dimensional model showing a viscous drag flow mechanism using a power-law equation for viscosity may be effectively used for predicting the behaviour of moist doughs during the extrusion process while the same model may not be very reliable for drier doughs which show plug flow behaviour during processing.