## 1 Introduction  
In 2023, around one out of five newly registered vehicles worldwide was a battery electric vehicle. Thereof, most electric vehicles were sold in China (60%), Europe (25%) and the USA (10%) [1]. In order to meet the demands of the drivetrain concepts of battery electric vehicles, the products of the supplier industry and the associated design requirements have changed drastically. In terms of the lubricating oil systems, a classic lubricating oil pump formerly driven by a combustion engine [2] is now being transformed into an electric oil pump that supplies fluid for powertrain cooling and lubrication applications [3]. There are various lubrication and cooling concepts that can be used for the cooling of the drivetrains of BEVs and hybrids. In industry, applications that focus on a combination of direct and indirect cooling are the most common. The oil is used either for the direct cooling of the windings by spray cooling or by overflowing the windings and for indirect stator cooling by cooling the motor housing [4]. Furthermore, the oil in the circuit also lubricates the gearbox, which is required for the transmission of the drive speed and torque [5]. Suppliers to the automotive industry typically offer so-called electric gerotorpumps for lubrication and cooling applications. Figure 1 shows a gerotor pump with an integrated electric motor and pump controller [6]. Compared to positive displacement pumps, centrifugal pumps in single-stage design are not able to achieve the required pressure ranges with the desired efficiency due to the space and acoustic (speed-limited) requirements in automotive engineering [7]. Gerotor pumps are generally preferred due to their simple design compared to vane pumps and their compact dimensions compared to external gear pumps [8; 9]. Furthermore, gerotor pumps feature low noise emissions through a precise and silent operation of the trochoidal gearing [10]. Gerotor pumps are positive displacement pumps and belong to the group of internal gear pumps. They consist of an outer gear whose center of rotation is positioned eccentrically to the inner rotor and has one tooth more [8]. There are already several approaches trying to develop electric oil pumps with increased efficiency specifically for use in electric powertrains. For example, investigations [11] show how the efficiency of the pump can be increased at a certain operating point by optimizing friction in the housing. Such investigations require the capability to simulate the pump both volumetrically and hydromechanically. In simulating pumps, both lumped parameter or 1D approaches as well as 3D CFD simulation methods are in use [12]. For example, ref. [13] analyzes the influence of cavitation on erosion with a CFD simulation, ref. [14] uses CFD simulation for noise mitigation prediction in gerotor pumps, whereas [15; 16] show a combined 2D/3D environment that can accelerate the design of gerotor pumps by using simulation methods in a web-based digital twin. In the 1D and lumped parameter approaches, it is examined how micro movements in the gerotor can be investigated using a journal bearing approach (outer gear to housing) [17; 18] and how a pump simulation considering fluid-structure interaction effects could be used to investigate the influence of material deformation at high pump pressures [9]. Additionally, ref. [19; 20] show how a gear set design and simulation can be performed for different operating conditions, even if [2] notes that 1D simulations are often used for instantaneous flow rate calculations and more research has to be done on the holistic optimization of inlet and outlet geometries. It should be mentioned that approaches for the automated optimization of gear set profiles using CFD simulations with dynamic mesh technology have already been shown by [21]. Other works [22; 23] have further shown that it is possible to simulate the pump efficiency and the corresponding torque at an operating point, if the geometric conditions of the pump are well known.