OpenFlume: An accessible and reproducible benchtop flume for research and education

Open-channel flumes are an important tool in fluid mechanics research and education. However, the few commercially available small-scale flumes are generally expensive and lack complete characterization. In this work, we present an open-source, low-cost, modular benchtop laboratory flume that is designed to be accessible and reproducible. The flume is assembled from widely available materials and hardware, and fabricated exclusively using tools and machinery commonly found in workshop spaces. The recirculating water flow through the system is driven by a controllable electric coolant pump designed for automobiles. Our design has a flow cross-section of 5 × 5 cm, adjustable flow velocity, and a modest overall footprint. All design files and build instructions are shared in a digital repository ensuring openness and reproducibility. The flow in the test section is characterized using particle image velocimetry (PIV) and is shown to be of high uniformity with low turbulence intensity. Furthermore, direct measurements of the drag force on a submerged sphere are reported for a range of control parameters, and exhibit good agreement with established empirical values.