Ter junctions, that are ubiquitous in stormwater systems. Numerical modeling research have largely assumed that the behavior of those junctions can be described by the application of mass, momentum, and power conservation principles. Despite the fact that it appears an sufficient strategy, it neglects the truth that, during pressurization stages, air pockets entrapment can seem, invalidating a number of hypotheses related to single-phase flows regularly applied in such numerical models [28]. Yet, there has been no investigation around the behavior of stormwater junctions undergoing pressurization, in spite of many and essential research on flow qualities at open-channel flow junctions. Pardee [29] BI-0115 manufacturer presented a study to derive the cost-free surface in hydraulic junctions taking into consideration various junction angles and conduit cross sections for both sub and supercritical flow regimes. Lin and Soong [30] performed a series of experimental investigations of flow traits in a 90-degree junction of a rectangular open channel and lateral channel. Lin and Soong [30] determined that the ratio among the lateral flow and the total flow was a crucial parameter to know the flow characteristics inside the junction. Also, bigger lateral flow rates provoked a backwater impact within the main channel upstream from the junction. Weber et al. [31] performed a careful characterization of flow traits, which includes the velocity field, within a 90-degree open-channel junction linking two reaches that had rectangular cross sections. In spite of these crucial scientific contributions within the description on the main traits and flow in the junctions of open channels, these investigations didn’t characterize the pressurization process in a stormwater junction, leaving critical open inquiries. In the discussion above, it becomes clear that there is a knowledge gap in the description of how stormwater junctions may undergo pressurization. Among the open investigation inquiries will be the following: Is it achievable to derive a flow classification scheme that qualitatively describes the pressurization, and eventual air pocket entrapment To what extent does an eventual air pocket entrapment pose challenges for the numerical modeling of junctions undergoing pressurization Can the information mining in the raw experimental dataset yield useful information for flow classification that matches experimental observations of flow pressurization at the junctionThis operate aims to address these concerns through an experimental investigation of T-junction flow pressurization employing video recordings and pressure monitoring. ClusteringWater 2021, 13,3 ofanalysis of the experimental data was also performed, and results of this analysis are compared with a proposed flow classification primarily based on experimental observations. Such results can (Z)-Semaxanib web support an assessment of irrespective of whether current numerical modeling tools for the simulation of rapid filling in stormwater systems are applicable. The manuscript is structured as follows: soon after this introductory section, the experimental information analyses approaches are presented and detailed in the Methodology section. The outcomes and Discussion section will focus on presenting the qualities of your flow, proposing a flow classification scheme, and differences in pressure results for representative flow conditions. Subsequently, the results from the clustering evaluation are compared with the proposed flow classification. Lastly, the Final Remarks and Conclusions section rein.