Pressure Measurements in Highly Viscous and Elastic Fluids

Abstract

Pressure measurements in flows of highly viscous and elastic fluids are of practical importance in polymer processing and rheology systems. Special problems arise during such pressure measurements. High fluid viscosity results in excessive dynamic response time (rise time) of the pressure measuring systems. This is true for systems that consist of manometers as well as pressure transducers attached to the base of a small hole at the wall. We model the dynamic response and examine related disturbing effects. These systematic errors in pressure measurements include hole-pressure effects, instabilities in cavity flow, and the time lag of the disturbance wave. We consider static and dynamic flow systems of a polymer solution (PIB/C14/PB Boger fluid) to study these problems and show that instantaneous pressure measurements in these systems can effectively be performed. [S0098-2202(00)02703-6]