• Net Volumetric Throughput of Single-Screw Extruders:
• In food extrusion rheology, the net volumetric flow rate ($Q$) through the extruder screw and die is governed by three superimposed flow mechanisms:

where:

• $Q_d$ (Drag flow): Forward conveying motion induced by viscous drag between the rotating screw surface and stationary barrel wall.
• $Q_p$ (Pressure flow): Reverse backflow driven by the adverse axial pressure gradient built up behind the restrictive die plate.
• $Q_l$ (Leakage flow): Backward leakage of melt through the radial clearance between the screw flight tips and the barrel bore.
• Conclusion: Drag flow - Pressure flow - Leakage flow (Option 2).

Correct option: (2) Drag flow-Pressure flow-Leakage flow