## 1 Introduction
### CFD Method in the Learning Context  
The CFD method has been used as a teaching resource for university studies, specifically, for undergraduate courses in engineering [12; 13; 14]. Nevertheless, simulation methods such as CFD and FEM are frequently offered as specific elective course in many academic institutions around the world for the acquisition of competence in simulation [1]. However, the assimilation of the learning of these types of tools involves long training times and it could be an impediment in the context of basic courses in engineering programs, considering the usual intensity of the scholarship for students and professors [15]. In this way, specific strategies can be used to integrate CFD in basic courses in engineering, specifically in the fluid-mechanics course [15]. The calculation of energy losses in pipes is an important skill which students must achieve in the fluid-mechanical course. Pressure drop in a pipe system is caused by fluid rising in elevation, shaft work, friction, and turbulence from sudden changes in direction or cross-sectional area [16]. Specifically, the calculation and application of pressure loss coefficients for different pipe sizes is important to calculate the energy loss and pressure drop in pipes and specific hydraulic elements installed in the line and, in this way, determine important parameters for engineering tasks, such as determining the correct pump size [17]. A summary of the published literature about pipes fitting in the learning context is established in [1]. When the pipe has a complex internal geometry or specific elements are installed in the pipelines (nozzles, valves, elbows, filters, etc. ), the energy losses can be obtained experimentally or through simulation tools such as CFD. However, pressure drop in singular elements can be also calculated using empirical tables and/or graphics, available in the literature (e.g., [11]). Unfortunately, the casuistry of this method based on the literature is reduced for several reasons: Limited number of head loss elements and also limited since ideal conditions are considered as ideal geometries for the elements, single-phase flow, Newtonian fluids, no consideration of the material type of the solids, etc. [15]. However, fluid-mechanical industry problems are sometimes more complex, including multiple phases, complex boundary conditions and complex geometry of the volume. These problems cannot be addressed using only the classic equations and empirical tables and/or graphics; nevertheless, they can be addressed using computer methods based on CFD. Thus, it is important that students, as future professionals, understand the scope and significance of this issue and the limitations of theoretical methods explained in the classroom [15]. Students tend to identify pressure drop with the concept of pressure drop \"in line\" (caused by friction with respect to the pipe). However, pressure drop is a wider concept which includes the local pressure loss caused by specific elements located in the fluid line, such as contractions or expansions, valves, etc. Due to this simplification of a complex reality, students sometimes ignore the fact that pressure drop can be caused by apparently insignificant anomalies in the geometry of the pipeline. Teaching this concept in a laboratory using experimental equipment is often expensive because some sophisticated stations and instruments are required [1]. Taking into account the high economic cost of the specific instrumentation, the amount of time spent doing the experimental tasks with the students, and operational limitations (e.g., presence of large groups of students) justifies the creation of virtual laboratory resources to support teaching activities [18]. These initiatives share many objectives with respect to simulation activities, insofar as they replace or complement experimental laboratory lessons.