What if energy is not conserved? A study on water flow through a circular orifice in a container

Understanding the limitations and potentialities of scientific models is a crucial aspect of learning Physics. One method to foster this understanding is through experimental investigation focused on assessing the implications of the idealizations considered in these models. Within this context, we present a study on fluid flow through orifices. We begin by analyzing a model widely explored in textbooks which, based on Bernoulli’s equation, does not account for energy losses. From experimental data collected via video analysis, we demonstrate that this model is inadequate for representing water flow, even in orifices with areas smaller than 1% of the fluid surface area in the container. Consequently, we propose a dissipative flow model, incorporating hydrology concepts that are rarely used in Physics education. We show that the predictions of this model are experimentally corroborated. Thus, this paper offers an experimental alternative for those wishing to explore a hydrodynamics problem with a focus on the scientific modeling process, aiming simultaneously to promote conceptual learning and understanding of the representational nature of knowledge.

Keywords
Hydrodynamics; flow; discharge; scientific modeling