# Towards Hierarchical Workflows in SysML to Support Virtual Validation of Technical Systems
###### Abstract  
Innovative Model-Based Systems Engineering (MBSE) applies function-oriented hierarchical system architecture and utilizes Systems Modeling Language (SysML) for virtual testing. However, for complex systems, the relevant virtual tests are scattered at different hierarchy levels. Manually performing these virtual tests requires a lot of effort and leads to the potential risk of errors due to the overlooking of some tests and functions. In order to solve these problems, it is necessary to develop automated virtual validation workflows for the function-oriented system architecture. This contribution proposes a standardized virtual validation workflow design framework corresponding to the hierarchical functional architecture to organize virtual tests. The virtual tests are also modeled in workflows consisting of a set of simulation activities that can execute domain models to simulate system behaviors. The simulation activities are developed modularly, corresponding to the classification of the domain models. The resulting workflows are implemented in a wind turbine (WT) system. It demonstrates that the workflows enable automated validation at all hierarchy levels and early detection of technical system failure risks. The design framework allows for the synchronous creation of validation workflows as functions are added or decomposed. The standardized design ensures easy redesign and function reuse across different systems. Modular design, based on model classification, enhances design agility and adaptability in various system contexts. The proposed virtual testing workflows automatically execute corresponding simulation activities sequentially. M 2023 16  
focuses on models rather than documents as the primary mean of information exchange for the management of complexity, synchronizing, and maintaining consistency [5]. In contrast to documents generated based on natural language, digital domain models have more rigorous semantics, which provides the possibility for standardized modeling. Based on standardized modeling, the MBSE approach can support the consistent design and bridge the gaps between multiple disciplines, reducing information exchange time while ensuring complex systems meet the requirements and handling trade-offs between requirements. One of the practical MBSE methods is proposed by [PERSON] [6] for function-oriented system development. The method adapts the Motego as a modeling approach to support the function-oriented development of technical engineering systems (e.g., WT systems). Although Motego is on its way to combining system models with domain models to simulate the system behaviors, engineers still cannot easily use SysML system models for system virtual validation. A comprehensive virtual validation process often relates to different functions at all system hierarchy levels and requires the participation of multiple virtual tests that performs the domain models in sequence. As the system becomes complex, it becomes inconvenient and unreliable to conduct these processes manually. A virtual validation workflow consists of orchestrated and repeatable activity modules that enable the virtual validation process by the systematic organization of virtual tests. Therefore, the objective of this work is to design a standardized framework based on Motego to model virtual validation workflows. The created workflows can organize various virtual tests and conduct the virtual validation of each function of the technical system. In addition, this work further standardizes the virtual tests in workflows based on simulation activities in the hierarchical system architecture. The contributions of this work are to provide an automated workflow that can be used for the virtual validation of functional requirements for multidisciplinary technical systems. The application of the proposed workflow enables engineers to reduce the manual work of virtual validation, and to achieve the reuse or redesign of the virtual validation workflows in different system contexts easily.