# A Virtual Prototype for Fast Design and Visualization of Gerotor Pumps
## 1 Introduction  
Gerotor pumps play an important role in the aerospace industry, particularly in the processes of cooling, lubrication, and fuel boost and transfer. In other sectors, the gerotor pumps are operated in a wide range of applications, such as dosing and filling technologies in pharmacy and medicine, dispensing technologies and coating applications in manufacturing, among others. The popularity of such pumps in industrial applications arises from the fact that gerotor pumps represent a reasonable compromise in terms of compactness, reliability, cost, and versatility [1]. The working principle of a gerotor pump is based on the interaction between a pair of toothed gears with trochoidal envelope profiles. The relative movement between the profiles generates a series of chambers with varying volume that perform a cycle of suction and delivery actions (in interaction with input and output ports), thus effectively producing a volumetric flow (see Figure 1). The current design process for gerotor pumps commonly involves: (i) a _geometric modeling_ step in a CAD environment, (ii) a _design verification_ phase using fluid mechanics simulations to validate the efficiency and other desired characteristics of the pump, and (iii) a _physical testing_ phase to verify the predicted characteristics of the pump in a real test bench once the design has been validated through a simulation tool. This process can be considerably time-consuming, due to the large amount of time that is required in the design verification stage. The design engineer must mesh the complex geometry of the volume chambers each time that the design is changed and perform a time-consuming simulation. In most design cases, the simulation of a geometric configuration takes up to a day to generate results. The described workflow hinders the effectiveness of rapid design methodologies or the easy testing of a large number of geometric configurations of the pump in a reasonable time. **Implementation**. In this manuscript, we present the implementation of a virtual prototype of a gerotor pump designed to be integrated with data measured in an experimental setup in order to improve the established design process. Our implementation does not constitute a full Digital Twin, but rather will be a step towards a fully functional Digital Twin tool that reproduces the behavior of the real pump. This virtual prototype allows for a rough design condition vs. performance appraisal, thus enabling the design and testing scenarios. Once the designer is satisfied with this approximated design vs. performance ratio, a more precise CFD simulation process would take place. An important current feature of the virtual prototype tool presented is the import and display of the sub-sequent CFD simulation results and experimental data measured in a real pump, for the benefit of the designer manufacturer and client. This feedback of the CFD simulation results might be included in a numerically oriented closed loop at the design stage. At the present time, we only report visual CFD data feedback. The implemented tool is able to use data that were measured in the experimental setup to feed the fast virtual prototype. Differences between the virtual prototype state variables and measured state variables allow for several activities: (a) to modify the pump design, (b) to control the actual pump, and (c) to feed satisfactory virtual prototype parameters into parametric or constraint-driven CAD models to obtain a full Boundary Representation of the gerotor pump. Notice that (c) streamlines the design-for-gerotor process and avoids the need for a external CAD application. The manuscript is divided, as follows: the Section 2 reviews the available literature in the context of physical simulation of gerotor pumps and Digital Twin implementations. Section 3 introduces the experimental setup of the pump, the lumped parameter model, and the virtual prototype tool. Section 4 presents the comparison between our predictions and a Computational Fluid Dynamics simulation used as ground truth.