Siemens Digital Industries Software announces the new release of Simcenter Amesim software, its market-leading 1D mechatronic system simulation platform. This version hosts noteworthy enhancements and implementations.

Let's see how the last version of Simcenter Amesim Embedded CFD can help you through a smart combination of 1D and 3D simulation environments

Assess the thermal comfort in a city bus with a multi-zone modeling approach



Vehicle thermal comfort challenges

The need to assess thermal comfort in all kind of vehicles is constantly increasing due to climate changes but also to the resulting energy savings objectives. Especially to assess the thermal comfort in a city bus.

The electrification of vehicles also drives these energy saving. In these vehicles, heating is not "free" anymore, as it was for internal combustion powered vehicles, getting similarly to cooling its energy from the batteries, thus impacting the vehicle range.

In the transport sector consequently, OEMs as well as suppliers are facing the challenge of handling thermal comfort very early in the design cycle to make quickly the best decision in order to avoid inefficient late iterations.

Introducing thermal comfort assessment in early design should give the correct trends, quickly and easily, not going into too many details since all the system components are not finalized. It should be logically assessed for a large variety of configurations and realistic conditions, i.e. during transient scenarios.

To answer this challenge, we often use system simulation without offering however a sufficient level of fidelity, due to the 3D nature of air flow phenomena.

The classical alternative in doing it with a full 3D CFD approach is also not optimal since CAD needs to be fully available and number of configurations that can be quickly handled is limited.

Overview of Simcenter Amesim Embedded CFD 2020.2

Considering the above-mentioned challenges, the Embedded CFD approach of Simcenter Amesim is de facto a good compromise combining the system simulation approach together with Simcenter STAR-CCM+ 3D CFD approach. Described as a hybrid tool between 1D and 3D CFD simulation environments, this tool benefits from both technologies. It offers the fidelity of 3D resolution together with close-to 1D simulation times, all encapsulated into an easy-to-use specific GUI.

The new 2020.2 version of Simcenter Amesim Embedded CFD for cabin comfort widens the possibilities. It can handle any type of cabin, ranging from a 2-seater car up to an entire commercial plane.

The user can now define its own geometry, the number of air zones, the location of air vents, the type of material (either opaque or transparent) and much more.

In addition to this important enhancement, we upgraded the compatibility with Simcenter STAR-CCM+ to additional versions (up to 2020.1).

Application to a city bus cooldown scenario with doors opening

A concrete scenario to assess the thermal comfort in a city bus with a multi-zone modeling approach will hereafter illustrate the usage of Simcenter Amesim Embedded CFD. Let's simulate an entire bus cooldown in a first phase, followed by 2 consecutive bus stops during which both front and mid doors open.

Simcenter Amesim model

The figure below illustrates the HEAT library containing the Cabin component.

This component has 3 external ports by default to connect on the left side the air vents boundary conditions in terms of air mass flow, temperature, pressure and humidity and on the right side the vehicle velocity and ambient air temperature.

Build 3D geometry

To build the 3D geometry from the above Simcenter Amesim model, we launch the Simcenter Amesim Embedded CFD app from the cabin component.

The step-by-step GUI guides the user towards the completion of the 1D-3D coupled simulation.

Let's start with the 3D geometry building.

The 3D geometry is built with XYZ coordinates and dimensions of elementary blocks such as boxes, cylinders, 3D polygons, etc. ... Elements can be of 3 types:

- Fluid: to create the fluid environment of interest (i.e. the resulting cabin air volume)
- Solid: to create objects that will be handled as solids exchanging heat with air
- Obstruction: to remove materials from the fluid domain (e.g. wheels)

We use cutting planes to split the global volume into air zones of interest. For our bus model, we define a total of 16 air zones as seen below.

To help the user building the geometry, note that we associate a dynamic 3D viewer.

Once the geometry has been completed, the 'Generate' button silently triggers a Simcenter STAR-CCM+ model in few seconds.

Defining boundary conditions and meshing the 3D model

In a second step, we can perform several actions:

- Renaming elements (volumes and faces) from the geometry
- Associating boundary conditions to a face (see below figure)
- Associating variables to be exchanged between Simcenter Amesim and Simcenter STAR-CCM+ simply using drag and drop
- Defining the average Mesh size and allowing the handling of gravity

Simulating a transient scenario

Before running the model, we generate automatically the 1D structure of the cabin during the '3D model to 1D sketch' step. The user might have at the beginning of this step to redefine the dimension of the MUX element connected to the cabin.

Once completed, the run can be defined and launched, and post-processed 3D results can be then accessed as shown on the figure below.

We can of course look also at transient results in Simcenter Amesim; the following picture shows the evolution of the 16 air zone temperatures during the cooldown.

We clearly see the impact of the 2 bus stops after 600s with a 30s door opening each time.

Let's now see more in details:

- How we couple Simcenter Amesim and Simcenter STAR-CCM+
- How we simulate the door opening

Details of 1D/3D coupling process

As part of the Embedded CFD workflow shown beforehand, we automatically generate the information exchanges between Simcenter Amesim and Simcenter STAR-CCM+ presented below. The user can add custom exchanges with Import / Export features.

Note that Simcenter STAR-CCM+ runs are performed as Steady-State calculations.

These events are associated with a Stop component and can be time-based or based on any system variable change.

In the example of the bus, there are 2 triggers:

- a time-based trigger with an increasing interval, so to be more accurate at the beginning of the cooldown
- a trigger linked to the bus speed, so to handle the doors opening and closing

The figure below illustrates the triggers:


Simulation of the doors opening

Let's now have a look at the doors opening simulation.

In the scenario of our bus example, we set the ambient temperature to 35 degrees Celsius.

When the doors are opening during the bus stop, we apply at the doors a mass flow calculated from the air density difference. For that purpose, we need to get the air temperature and humidity from the air zones next to the doors as illustrated below.

The analytical model used has been defined by Pham and Oliver [ref.]:

This results in the following mass flow profiles:


Note that the opening / closing is considered here as instantaneous, which can be of course adjusted to be more realistic.

We have demonstrated that Simcenter Amesim Embedded CFD is the right tool to assess the thermal comfort in a city bus with a multi-zone modeling approach, especially during early design stages for which decision making is essential.

Platform facilities

Export post-processed variables to CSV data files

* Ability to export to a CSV file a selection (or all) of the post-processed variables
* Possibility to export to CSV files the post-processed variables from a batch simulation

Sketch-building enhancements


* Hops at intersections between lines
* Transmitter and Receiver usability enhancements (permissive Port Tag List, quick actions)
* External variable view improvements

Analysis tools

2D Mechanical Assistant: digging bucket display

* Check parameter settings of heavy machines that comprise digging buckets in the 3D scene of the 2D Mechanical assistant
* Animate digging forces from simulation results

Description: animation of time series from test data

* Identify the time variable of the test data to support time-related features when loading them in a Description window

Customization

3D API: 3D object animation

* Animate 2D or 3D drawings that are integrated in your apps
* Control the animation playback with the built-in animation toolbar
* Create simple pre-defined ground displays for driving dynamic application
* Apply textures on 3D objects for better visualization

Solvers and Numerics

Use custom Python scripts for pre- or post-processing on remote HPC


* Attach a pre or post-processing Python script to a study, to run it remotely on the HPC cluster
* Download only the desired post-processed data instead of the full Simcenter Amesim model with all its intermediate run results

Enhanced batch run support for HPC in the Study Manager

* Use HPC capabilities for batch simulations more easily within the "Study Manager" tool
* Attach pre or post-processing Python scripts to batch simulations on HPC

Software interfaces

Open Neural Network Exchange (ONNX) Interfaces


* Python scripts called "OnnxToAme" and "OnnxToFMI" allow exporting ONNX files as native Simcenter Amesim submodels or as 2.0.1 Functional Mock-up Units (FMUs)

Export of Functional Mock-up Units (FMUs) not requiring runtime licenses

* Export of Functional Mock-up Units (FMUs) not requiring runtime licenses and, most of the time, not requiring any Simcenter Amesim installation
* Available on standard Windows 32-/64-bit or Linux 64-bit platforms, restricted to model exchange or to co-simulation with fixed-step solvers

1D/3D CAE

CAD Import: piping wizard

* Automate the whole CAD Import process from the 3D object splitting to the primitive to primitive connection creation for piping networks

CAD Import: PLMXML import

* Ensure interoperability in between Siemens software applications
* Share unique model definition for 3D simulations and system simulations

Modelica Platform

Enhanced custom exposure settings for the Modelica model

* Ability to activate/deactivate additional parameters from the Optimica Compiler Toolkit when importing a Modelica model

MiL, SiL, HiL and real time

Simulink Interface improvements


* Simcenter Amesim to Simulink S-function blocks (AME2SL and AME2SLCosim) can be used inside Simulink "linked libraries" (no broken links anymore)
* Simcenter Amesim and Simulink models can now be located in distinct folders (limitation removed)

Automation Connect improvements

* Improved support of PLCSIM Advanced
* Capacity to link multiple variables to a single control in the dashboard
* Various user experience improvements
* Connection to Simcenter Flomaster

The library has also been updated. For details on these new features and enhancements, refer to the manual .pdf files available from the Help menu in each module or from the Manuals folder on your hard drive.

Simcenter Amesim allows system simulation engineers to virtually assess and optimize the performance of mechatronic systems. This will boost overall systems engineering productivity from the early development stages until the final performance validation and controls calibration.

Simcenter Amesim includes ready-to-use multi-physics libraries combined with application and industry-oriented solutions that are supported by powerful platform capabilities, to let you rapidly create models and accurately perform analysis. It is an open environment that can be integrated into your enterprise processes. You can easily couple the software with major computer-aided engineering (CAE), computer-aided design (CAD) and controls software packages, interoperate it with the Functional Mock-up Interface (FMI), Modelica, and connect it with other Simcenter solutions, Teamcenter and Excel.

Alberto Soto, Technical Product Manager at Siemens PLM Software, explains how to optimize vehicle thermal comfort using the Embedded CFD Cabin capability of Simcenter Amesim.

Siemens Digital Industries Software is driving transformation to enable a digital enterprise where engineering, manufacturing and electronics design meet tomorrow. The Xcelerator portfolio helps companies of all sizes create and leverage digital twins that provide organizations with new insights, opportunities and levels of automation to drive innovation.

Product: Siemens Simcenter Amesim
Version: 2020.2.0
Supported Architectures: x64
Website Home Page : www.plm.automation.siemens.com
Language: english
System Requirements: PC / Linux *
Size: 8.8 Gb