Nodes - IDOC

An IDOC is an acronym standing for “Independent Domain Of Computation”. If you look under the grid fluid icon, you can see a total of three entries: “Splash per IDOC”, “Foam per IDOC” and “Mist per IDOC”. Another location for IDOCs can be found right to the RealWave icon. From this menu you can add IDOCs for both standard and grid fluids, and simulate them over your network. This method is perfectly suited for side-by-side comparisons, for example.

Left image: fluid interaction without IDOCs; right image: fluids inside IDOCs simply go through each other.

The idea behind IDOCs is that you can perform multiple simulations within a single scene, but on different machines. The most important aspect with this node type is that the emitters are calculated separately from each other. This means that RealFlow does not simulate interactions between the IDOCs, respectively the individual emitters. For that reason it is possible to simulate emitters, which are encapsulated in IDOCs, over a network on different computers. This principle works for both Hybrido secondary elements, the so-called HySPH emitters and standard particle sources – the SPH emitters.

At first glance, it seems as if this simulation mode is a disadvantage, because you obviously lose detail when the particles from different emitters cannot interact. In fact, you will not recognize any difference. Only in cases where you really need interacting fluids, for example when you want two or more fluid sources to collide, you cannot use IDOCs. Another, very interesting, feature is that you can combine multiple emitters within a single IDOC and these particles will be able to interact. Of course, this can also be done with the “Relationship Editor” and appropriate links, but then it is not possible to distribute the simulation over multiple machines. Using IDOCs is like separating the fluid sources to prepare them for network simulations.

Adding an IDOC node is the first step, but it is actually nothing more than creating an empty container without a function. The real power of IDOCs is the "Job Manager", which finally splits the simulation into several computational domains and passes them to the connected computers. Before you can start, the appropriate “Job Manager” settings have to be made. For a detailed description how to install and configure this tool, please read the “Job Manager (JM)” chapter.

Furthermore, please note that network simulations can only be performed with an appropriate number of licenses. For each computer you want to use, a “RealFlow Node” license is required. With a standard “RealFlow GUI” license, network simulations are not possible. For more information about pricing, bundles and interesting offers, just visit http://www.realflow.com/pricing/ or contact our Salesdesk team (http://www.realflow.com/contact_us). We look forward to hearing from you.

IDOC – Basic Workflow

Here, a typical Hybrido scene is prepared for splash generation and subdivided into multiple independent areas – the IDOCs. The mode of operation is almost the same for standard particle emitters, but for Hybrido's secondary elements there is a very convenient way of attaching the emitters to IDOCs with a single click using the “Splash per …” functions from RealFlow's Hybrido node set.

When you use IDOCs for Hybrido simulations, a core fluid is required where you add splashes and foam. Only these HySPH elements can be simulated with the help of IDOCs, while the underlying, main body of fluid (the actual grid fluid) has to be generated on a single machine. With standard SPH emitters, the IDOC method can be used from the very beginning.

The creation of IDOCs is an easy task and you can either start with an IDOC or an emitter/secondary element node. The IDOC is by default a cubic domain with a size of 1m x 1m x 1m, and it can be scaled like any other RealFlow object. The next step is the creation of an emitter. To be recognized, the emitter must be located inside an IDOC, though the exact position does not play a role. It is actually only important that the emitter’s viewport symbol lies within the appropriate box. Once this has been done, it is time to connect the emitter to the desired IDOC – that is just a drag and drop thing. Grab the emitter and drag it onto the appropriate IDOC. All this is done within the "Nodes" panel and that is already all you have to do at this point. It is even possible to attach multiple emitters to a single IDOC and these particle are able to interact. To add more domains, either repeat this process or directly use the following method for multiple IDOCs.

The second option is, as already mentioned, only available for Hybrido splash, foam and mist elements. This feature detects all existing IDOCs in a scene and attaches the appropriate number of splash emitters to the IDOCs:

Edit > Add > Hybrido > Splash per IDOC

Another convenient way of using more than one IDOC is to use the “Multiple” node. The workflow is slightly different, but still very user-friendly. Instead of creating the domains one by one, “Multiple” can be used to add the desired number of domains in one pass. For this purpose, you should start with a cube object. Resize the cube to enclose all available emitters or the area where secondary elements should occur. Go to:

Edit > Add > IDOCS > Multiple

A dialogue box will open, asking you how many subdivisions RealFlow should add. Here, 2 x 2 IDOC nodes in horizontal direction (mind your axis setup) are needed.

In the next step you will be asked which node you want to use to create the IDOCs – here it is the cube object that will serve as a template. The result are four IDOC nodes, representing the boundaries of the cube exactly. You are not limited to cubes or box-shaped items – in fact you can use virtually any form, but RealFlow always calculates a bounding box around the supporting object to draw the IDOCs. Since the cube object is not needed anymore, you can delete it. If you are not happy with RealFlow’s automatic setup you can still rescale and move everything. The IDOC nodes can also be spread over the entire core fluid area and do not necessarily have to touch.

Once you have subdivided the emitters and IDOCS, you can start the "Job Manager" program and all computers with “Job Node” applications. Finally, open the “Job Manager” inside RealFlow to monitor the simulation progress and append your job to the simulation queue with

[ Selected IDOC ] > Node Params > IDOC > Send to job manager

This button has to be pressed for each IDOC individually to add it to the queue. When the “Job Manager” recognizes computers with running and licensed “Job Nodes”, the simulation will start automatically.