Correction factors for the drag and pressure flows of power‐law fluids through rectangular ducts

Abstract

There are many industrial examples of low Reynolds number non-Newtonian flows through rectangular ducts in polymer processing. They occur in all types of manufacturing processes in which raw polymeric materials are converted into products, ranging from screw extrusion to shaping operations in dies and molds. In addition, they are found in numerous rheological measurement systems. The literature provides various mathematical formulations for non-Newtonian flows through rectangular ducts, but-if not simplified furthertheir solution usually requires use of numerical techniques. Removing the need for these time-consuming techniques, we present novel analytical correction factors for the drag and pressure flows of power-law fluids in rectangular flow channels. We approximated numerical results for a fully developed flow under isothermal conditions using symbolic regression based on genetic programming. The correction factors can be applied to the analytical theory that describes the flow of power-law fluids between parallel plates to include effects of the side walls in the prediction of flow rate and viscous dissipation.

Extended melt‐conveying models for single‐screw extruders: Integrating domain knowledge into symbolic regression

“…To this end, the numerically computed solutions for the target variables Π V and Π Q were corrected by subtracting the results of analytical approximations available for a simplified onedimensional case (described by Π V ,app and Π Q,app ). 39,44 To reduce the ranges of the target variables, the numerical results were corrected as follows:…”

“…To additionally account for the effect of the side walls in the definition of Π V ,app and Π Q,app , the following correction factors were applied 44 :…”