Fluid Flow Visualization using an Improvised Reynolds’ Apparatus

Abstract

In studying fluid mechanics, the Reynolds’ apparatus is a fundamental tool for demonstrating how fluid flow in pipes transitions from laminar to turbulent regimes. However, commercial units can be prohibitively expensive for many institutions, limiting practical, hands-on experiences. In this work, a low-cost Reynolds apparatus was designed and constructed using locally available materials at a total cost of approximately Php 4,010 (about 70 USD). The system was validated by comparing observed flow regimes—ranging from laminar to turbulent—with those predicted by computed Reynolds numbers, and a strong correspondence between theory and observation was found. Further investigations were conducted on the effects of fluid velocity and temperature (and thus kinematic viscosity) on the Reynolds number. As expected, the Reynolds number is raised by increasing the flow velocity, while raising the fluid temperature lowers its viscosity and thus further elevates the Reynolds number. Notably, with tap water used as the working fluid and a test pipe of 2.2 cm inner diameter, Reynolds numbers as high as 67,715 can be achieved, allowing the study of highly turbulent flows. Given its affordability and demonstrated accuracy, this improvised Reynolds’ apparatus is deemed well-suited for instructional and research applications, particularly in settings constrained by limited budgets.