VALIDATION AND DEVELOPMENT OF DISCHARGE EQUATIONS FOR 3D PRINTED FLUMES FOR FLOW MONITORING

Flumes are specially shaped, engineered structures that have been used widely for measuring flow. Flumes are typically fabricated from aluminum or fiberglass; however, these types of flumes can be costly if purchased commercially and may lack machine precision if custom fabricated. This limits availability for widespread monitoring by smaller municipalities, engineering firms, or researchers with limited budgets. Using 3D printing technology (additive manufacturing) to produce flumes is very cost-effective, but variability between flumes and materials has not been tested, and discharge equations have not been developed for 3D printed flumes. In this study, a laboratory-scale setup was used to develop discharge equations for two types of 3D printed flumes (0.122 m HS flume and 0.102 m Palmer-Bowlus flume) made from two 3D printing materials: polylactic acid (PLA) and polyethylene terephthalate glycol modified (PETG). Variability between the same type of flume and between different materials for the same type of flume was analyzed to evaluate the consistency of the discharge equation with flumes of the same type. Eight models were developed to fit each dataset (PLA, PETG, and combined PLA and PETG) for both flume types and evaluated for goodness-of-fit and information criteria (AIC and BIC for model parsimony) to select the discharge equation for each flume type. Discharge equations were consistent for the same type of flume across each print and across different print materials. The discharge equations of 3D printed 0.122 m HS flumes and 0.102 m Palmer-Bowlus flumes are Q = 0.45624 × H^2.351 and Q = 0.0001176 + 1.309 × (H - 0.0174625)^2.235, respectively. The discharge equations of both flume types had R²_adj values greater than 97% for the measured data of each individual flume. Both 3D printed flumes were consistent in measuring flow and are suitable for hydrologic monitoring.