STAR-CCM+ v12.04 preview: Out with the old, in with the new

By James Clement

or,  how to be ridiculously effective with STAR-CCM+ 12.04

I have to say, if you haven’t yet taken a look at the latest release of STAR-CCM+, version 12.04, now is the time. Design Manager, Expanded Dynamic queries, 3D-CAD to Parts Sync and Replace Assembly all coming out in one release means there is a confluence of features that can make every user more effective in nearly every application of STAR-CCM+. In today’s blog, I want to shine a light on one of these four features, Replace Assembly, hence the blog title.  

The mantra I hope that I instill by the end of this discussion is: “Never set up a new design from scratch again.” In our world of multiple vendors, design groups and test revisions, the lowly CFD engineer doesn’t have the luxury of only running one design and calling it a day. We have all experienced getting a simulation almost done and then an email comes in with a new part, or worse, you are going to present results and the client says, “wait, that’s not the latest design.” We need our tools to be able to be as adaptable as we are and that is where this new replace functionality comes in.  This enables you to simply swap in the new design and hit go.  No need to re-build scenes, or update reports which reference the old parts. It’s as simple as that.

I keep saying replace this and replace that but I don’t think I have really explained what is happening under the hood and why this new incarnation of an old feature is so good. Let’s start with how replace works. As a user you import your model and put the appropriate parts and surfaces into mesh operations, physics, boundaries, scenes, reports and various other places to build up your simulation.  You can imagine what you have done as placing the original or a dependent version of your part or part surface in 20 to 30 “bins.” If you wanted to change your input part you would effectively have to go find all of those bins and replace the old with the new. So what we can now do, and what happens in replace, is leave the old part object alone and simply swap the geometric definition to be the new version. We are effectively not changing the part object in its 20 to 30 bins, we are just changing the shape of that part. It’s pretty slick.test


This new incarnation of replace offers the user a much more robust and flexible process that can now be part of a pipelined process. Aside from the fact that replace part is now an operation, the single biggest change is that you can now replace any part in the tree with any other part in the tree. This is important as it allows you to interact with your new design before replacing. You can split faces, do booleans, repair, you name it. If you don’t know where a new face should go you can set up a part surface in the old design that will be a catch-all for any new surfaces that cannot be matched by name.  

Hopefully, now you have an understanding of the replace concept in STAR-CCM+. In our latest release, we have improved and built on replace part so that the same operation can now take full assemblies.  This means that you can swap 5,000 parts in a single click if you need to! In my opinion, replace assembly adds a whole new dimension to design iterations and exploration.  

Assembly replacement is fundamentally the same as part replace but there are some extra options that enable more flexibility. The replace operation simply swaps in a new geometry definition underneath the old part object, so when replacing assemblies we give you some choices on what to do with mismatches. The first option involves what to do when the new assembly doesn’t have the same number of parts as the old one. If a new part does not match with the old, you can clear the geometry but leave the part object, clear the geometry and delete the part, or do nothing. This last one is the most important. Imagine we have a quadcopter assembly like the one below. In the CAD system you can simply hide all of the components that have NOT changed. When you export the geometry only the changed parts will be written out. Replace part will then enable just the replacement of the changed components while leaving the others alone.  



Replace part grants you, the engineer, the confidence to say “No problem” when your manager walks in with a completely new design two hours before the meeting, because you know your toolset is built to be as nimble and adaptive as you are. If you haven’t done it already, fire up STAR-CCM+ 12.04 and give these new features a run for their money; I am sure you will have a smile on your face in just a few clicks.  


This article first appeared on the Siemens Digital Industries Software blog at