This week´s second Volupe blog post will be a bit different (the first one can be found here: Marine Advancements – Simcenter Amesim – VOLUPE Software). It will be a guide, or a reminder, on how to utilize the documentation of Simcenter STAR-CCM+. The documentation (user manual) of the software is always accessible with your installation of the software. Once a question arises for you as a user, you have several options for answers. The official options you have are, Support center knowledge base (Support Center (siemens.com)), the documentation, and of course other blog articles from the Volupe blog. (Blog posts Volupe – VOLUPE Software).
How to access the documentation?
The easiest way to reach the documentation is to open your Simcenter STAR-CCM+ GUI and press F1. This will open an html-link in your browser where you can navigate freely in the documentation. This procedure also shows you where the installation of STAR is located. This is by far the smoothest way to navigate around.
Note that the user guide for each separate version also can be found in the same location as your installation. There is a PDF-document available also (with 12 000+ pages).
What information can I find in the documentation?
Mainly when questions arise, the two main locations in the documentation are “Simulating Physics” and my favourite the “Theory” section.
In the simulating physics section of the documentation some theory is combined with information regarding how models are selected and what models can be selected together. It gives a description of models, when to use them and what regimes they are applicable in mainly. It gives a description of how some models work. I can also give, as in the example with batteries here, a terminology overview and description.
Note also that there might be examples in the documentation that shows you a method. Meaning, how to combine settings in order to create a function or a method that is not necessarily an out of the box model selection. These types of additional setups are usually found in the Knowledge base on the support center, but some also exist in the documentation.
One example of the above information found in the documentation is for instance how to use passive scalar as a tool to calculate residence time in a steady state simulation. It gives a point list of the procedure to include this in your simulation. It also gives you the field function you need to create for recirculation zones not to reach infinity in residence time. I highly recommend looking in the documentation for methods and for tips and tricks to some extent.
The theory section includes exactly what it sounds like, the theoretical framework for basically all models and closures in Simcenter STAR-CCM+. Activating a model in Simcenter STAR-CCM+ often also opens for the possibility of changing the constants related to that specific model. The theory section can then give a notion on what constants you need to consider, and perhaps also a description of the availability of the default values for those constants. Only because you have a selected a model, it is not automatically fitted to your materials. Let’s look at an example regarding the NTC collision model available in the Lagrangian framework in Simcenter STAR-CCM+. The NTC model is calculating not only collision and breakup rates for particles colliding in a Lagrangian phase, but also the collision efficiency and resulting velocities for the resulting droplets.
Describing this a bit simplified; the impact parameter, B, is used to decide the collision efficiency, E. The collision efficiency is then inserted together with Weber number (a particle property) into the selected collision outcome map (for brevity I use the O’Rourke Map in this example). Based on where you end up in the collision outcome map, what happens from the collision is decided. Your particles can bounce, coalesce, or graze. The problem here is using these curves for any arbitrary system. Because further investigation shows that the separate curves come from expression (1.). The constants in (1.) are given with DEFAULT values in (2.). This is important, these constants are parameters that should be fitted to your system, not to be used for the arbitrary system. Further, something called the droplet diameter ratio correction (3.) is also included in (1.). It is also related to several constants (4.) that should be fitted to the droplets you have in your system.
The point here is to look in the documentation and investigate what you are actually doing when selecting a model. What is the applicability of the model and when should it not be used?
Model, solver and field function references
The model reference provides you with a link to the theory section for the specified solver. It also shows which other models that need to be selected in order to reach the one you are investigating, this under the “Provided by” section. It gives information of what requirements the model has, in terms of what Material you can use with the model. Let’s use the Lagrangian Multiphase as an example below and look at the Model reference for that.
The solver reference gives information regarding the solver properties and the sub-solvers associated with the model of interest. It describes the terms and properties of the solver and sub-solver. A good place to start looking when you are unsure of any setting for the solver, or what the meaning of that setting is.
The field function reference node describes the field functions that becomes activated when the solver in selected. The field functions can provide you with data for scenes, plots, reports, monitors, and tables.
The tutorial list is quite comprehensive and is an important part of the documentation. The list of tutorials is given with several tutorials associated with each field. Always a good starting point if you venture into a new field that you have not worked within before. It is used in conjunction with the tutorial files found in the tutorial suite that can be downloaded for each version of the software from the support center.
In the theory section, under each separate chapter there is a bibliography, a reference list. When a section is connected to a reference in the list, there is a hyperlink that takes you to the bibliography and you can trace the reference for further information. Looking back at our example with the NTC collision model, the origin of the values assigned to constants in the models can be found. Use this when questions arise regarding definitions.
Again, let’s use the bibliography for the Lagrangian multiphase solver as an example. The below picture gives an example of what a bibliography can look like.
I hope this has been useful for you as a user and given you some more information in how to obtain answers when questions arise. Many answers can be found if you know where to search.