Field Function Editor creating a complex equation.
Today marks the release of CD-adapco’s STAR-CCM+ v9.04. The new release promises that users will see an improvement in workflow and productivity, reducing the time it takes to produce your simulations. So let’s dig down to see what improvements will help you get your work done faster in v9.04.
When setting up your simulation, the field function editor will allow you to easily set up variable conditions in the simulation. This is done by constructing customized expressions called Field Functions. In the past, these expressions could easily get complex and out of hand. To assist in this, the Field Function Editor can set up variable boundaries by constructing an equation using variables and functions in a drop down menu.
“Previously you needed to know the syntax,” explains David Mann, STAR-CCM+ Product Manager at CD-adapco. “This tool allows you to pick things from a list and works a bit like a calculator. For example, you can select time and then take the sine of that function. This would produce a sine function of time which you could then further edit. Then you could use that function as an input elsewhere in your set up. You can quickly build complex field functions.”
In addition to the field function editor, v9.04 has a dependency viewer that allows you to see what dependencies are located in which expressions and where (from reports, monitors and plots). This helps you avoid annoying error messages when deleting a monitor.
Concurrent Per-Part Meshing
Parallel meshing (left) vs Concurrent Per-Part Meshing (right).
Version 9.04 also has a new method to mesh your large assemblies called Concurrent Part-Per Meshing (CPPM). Instead of STAR-CCM+ partitioning the model to allocate model sections to cores for parallel meshing, CPPM will skip this step and send each core a single part assembly.
“Let’s say you want to mesh a circuit board with 100 components. In the past STAR-CCM+ would take each part and mesh them sequentially in a single processor. CPPM can use as many cores as you want. If you have 101 cores each part will be meshed by a separate core at the same time. The extra core will be used as the controller, sending new parts as each core finishes its task,” explains Mann.
In a separate example, Mann reports that CPPM has cut down the meshing of a car model with 947 parts from seven hours to an hour and a half. “This offers an extra degree of freedom. This method of meshing is well suited to complex assemblies with large numbers of parts that all have to be meshed (For example, under the hood of a car or electronics thermal management simulations where the solid regions are also meshed). For these geometries this type of meshing will perform very well. For cases where you have relatively few parts or one main volume then one of the other parallel meshers should be used instead,” says Mann. Essentially, CPPM offers yet another way to customize your approach. Sometimes it will be ideal and sometimes you’ll get faster results using another parallel meshing tool.
Co-Simulation API
One very powerful tool added to STAR-CCM+ is the co-simulation application program interface (API). Though this tool is already well known in other simulation software like ANSYS and FEMAP; the addition of API will increase the user’s freedom by allowing custom interaction with third party software.
This will allow for easier multiphysics simulations using surface to surface data exchange such as thermal or mechanical fluid properties. This can then be sent to a structural simulation in Abaqus or ANYSYS.
“Using the Co-Simulation API users can build their own links with 3rd party tools. STAR-CCM+ has had the ability to Co-Simulate with specific third party simulation tools before, however, now you don’t have to wait for us to add links to additional tools, you can program it yourself,” says Mann.
The API is compatible with many programming languages including: C++, Fortran, JAVA, Python, Simplified Wrappers and Interface Generation.
Dynamic Fluid Body Interaction Contact Coupling
Speaking of multiphysics, STAR-CCM+ has upgraded their Dynamic Fluid Body Interaction (DFBI) solver’s interactions with their Overset mesh (or mesh morphing) by allowing for collisions between objects.
The DFBI is a 6 degree of freedom solver which calculates the effect of fluidic forces and moments on a body. The Overset mesh on the other hand allows for simulations to run off a background and foreground mesh. This allows for movement of the foreground body in response to the forces calculated by the DFBI at each time step. The Overset mesh will not tie up the meshes as the body moves, it will simply interpolate between them.
“Before, if a DFBI body hit a boundary it would go through it. The simulation would essentially need to stop there. Now the simulation runs with a DFBI body that can effectively bounce off the wall if it collides with it. In fact, such simulations are typically set up so that the object bounces off the 3rd or 4th prism layer (from the boundary) to maintain a few layers of mesh in the gap (a current requirement of Overset mesh), but this gap can be as small as you can make the mesh. Previously it was necessary to couple with a 3rd party tool to do this simulation. Now we can do it internally all in STAR-CCM+,” explains Mann. This simulation is perfect for the ball valve seen above.
Contact coupling can be used with any of the other DFBI coupling models, such as the catenary coupling model which can be used to simulate a moored boat. “Basically, the key aim is to make our capabilities work together. Multiple physics solvers and capabilities working together in the same simulation. The goal is to make solvers connect where appropriate so you can simulate all the physics that exist in real applications,” expresses Mann.
Coarse Grain Particle Lagrangian Model
Another interesting solver advancement can be seen with the DEM Coarse Grain Particle Model. This is a Lagrangian model typically used to model discrete particles. Traditionally, the simulation tracks a large number of particles instead of assuming the fluid is a continuum. These particles of various shapes can bounce off things like billiards in a 3D model.
Traditionally, tracking this large number of particles was CPU intensive due to the collisions of the particles. “STAR-CCM+ has a new ability to lump together large numbers of these particles into coarse parcels. These coarse parcels are then used to solve for the contact dynamics, reducing the computational expense. The fluid-particle dynamics, however, can then be calculated using the traditional fine scale particles,” says Mann.
Mann explains that in a fluidized bed example, which had over 1.7 billion particles and 100,000 parcels, they were able to simulate 0.1 seconds in seven minutes using 72 cores. In the previous solver this number of particles would be impractical to solve.
Other Improvements and Idea Storm
Other than the aforementioned highlights, v9.04 has seen many other improvements including multiple cost functions in the adjoint solver, an object search/filter function, improved volume rendering and an interactive color map editor. A summary of the improvements can be seen in the table below.
| Pre-Processing | Models | Post-Processing |
|---|---|---|
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With all of these developments, the fixes you really want might fall through the cracks. However, you can send your suggestions for further software improvements using IdeaStorm – CD-adapco’s tool for crowdsourcing program improvements.
“Our product strategy … is one of anticipating the needs of industry when determining what new features to put into the software. Targeting new application areas and industries, but also being responsive to our customers to satisfy their needs in terms of what it is they are trying to simulate and what additional capabilities they need to do that,” said Mann.
Clearly CD-adapco is capable of looking at the big picture and listening to their audience at the same time; something important for the largest privately held CFD focused CAE company to keep in mind.
Images courtesy of CD-adapco