Getting started

This is a quick-start guide on how to use the library and to simulate a first example. It is assumed that the user is already familiar with working with their Modelica tool.

The library package is a read-only package that contains the model library with components and templates. To modify and build new models, a user-writable working package has to be created, where users can work with examples and store new or modified models and components. Since tank models and the method in which heat transfer is handled within them is very important, a section explaining them is provided below.

General Setup

All experiments and most models in the FuelSystem library depend on their environment. The surroundings in are described by integrating four different models:

  • Atmosphere: The functions for calculating the atmosphere conditions, e.g. temperature, pressure, humidity etc. need to be specified in an atmosphere component. Since many component models use an outer atmosphere model, it is always recommended to place and inner atmosphere model on an experiment model.
  • AirData: Position specifications for any submodels uses an airData model to extract values for atmospheric properties from the atmosphere model in a specific location. The separation of atmosphere and airData model enables the usage of multiple airData models at different positions, speeds or acceleration while relying on the same atmosphere. This approach is needed for simulations with multiple vehicles in a single experiment. Since many component models use an outer airData model, it is always recommended to place and inner airData model on an experiment model.
  • WorldRepresentation: The world representation defines if for the coordinates they are given in Cartesian coordinates x,y,z (���FlatEarth���) which is the default or if they are given in for a flat earth in north, east, down coordinates or a spheric description of the globe is used and coordinates are converted accordingly. Since many component models use an outer worldRepresentation model, it is always recommended to place and inner worldRepresentation model on an experiment model.

A simple example to illustrate this concept is available in Modelon library: Demonstration

In addition to the general concept that is used if different Modelon libraries, the FuelSystem library uses specific parameters and settings:

  • Settings_FSL: library specific settings and assumptions are specified in this component, e.g. for Real time simulation, visualization but also for general assumptions. Since many component models use an outer settings_FSL model, it is always recommended to place and inner settings_FSL model on an experiment model.


Look at the experiments section for experiments that can be readily simulated.

Tanks and HeatTransfer

Three different tank models are available in the library. The simple tank models a cuboid geometry tank. Heat transfer is not accounted for in this model. This functionality is added in the simple tank with convective heat transfer. The most complex tank model available is the complex tank.

The complex tank can model any complex geometry of a tank loaded with the aid of a STL file (exported from CAD software) or manual entry of surface triangulation details. This model also has capability to capture the heat transfer effects.

Heat transfer in simple tank

The heat transfer in simple tank model is handled per side of the cuboid. There are six heat ports with different names representing the six sides of the cuboid geometry of the tank. For each heat port, the user shall provide a wet and dry heat transfer coefficient (convective). Based on fuel and gas level computation within the tank, the wet coefficient is used to calculate the heat transfer between the area in which the fuel is in contact with the particular side of the tank. The remaining part of the side must obviously be in contact with gas, and thus the dry coefficients are used for computing heat transfer. See the documentation of the simple tank with convective heat transfer for more information.

Heat transfer in complex tank

The number of heat transfer ports is variable in the complex tank. The user can input the number of heat ports as a parameter. Then, the user can also link each of these heat ports to a set of triangles that make up the entire tank through a parameter record listOfTriangles. The users of complex tanks are provided with different heat transfer models. For instance, the user can select a constant coefficient method like in the simple tank or empirical correlations that are specific to the complex tank.

The geometry models for complex tank comes in five variations namely Modelica with visualization, Modelica without visualization, External without visualization, Explicit External without visualization and Explicit External with visualization. The heat transfer computations also require outputs of the geometry model computations so that correct heat transfer areas are available (wet and dry portions). To support this, the heat transfer model defines the heat transfer query angles. The geometry kernel then returns the surfaces per query angle to the heat transfer models where heat transfer coefficient is estimated based on the correlations. These query angles are important to distinguish different surfaces such as horizontal top surfaces, and horizontal bottom surfaces that both have different heat transfer characteristics in case of free convections. All geometry models have the capability to compute and handle the query angles for heat transfer. See the documentation of the complex tank for more information