The Simulation engine in InfoWorks ICM is very efficient and needs very little RAM for 1D pipe and channel networks. Even for quite large models containing many thousands of pipes and manholes, InfoWorks ICM only needs 100’s of Megabytes of RAM for the Simulation, not Gigabytes. With that said, it is worth noting that Water Quality Simulations do require significantly more resources than basic hydraulic calculations. It’s the number of processors, the clock speed of each processor, and how many cores each processor contains that determines how quickly your runs complete.
However, runs of 2D models require much more RAM right from the outset. The pre-processing of the 2D mesh requires that the whole model is loaded into the available RAM at the start of the Simulation. The memory of the PC and the GPU are treated independently. The PC needs enough to manage the initial set-up, model initialisation and all subsequent I/O during the run. The GPU needs enough RAM to handle the 2D mathematics that are passed to it.
It’s important to note that all simulations, even pure 2D simulations, are still reliant on the main PC (i.e. CPU), even if the computer has a powerful GPU card. It’s only the 2D mathmatics that are done on the GPU, everything else stays on the CPU.
The image above is from a PC with a Core i5 processor, 6Gb RAM and an nVidia GeForce GT440 2Gb GPU which shows the different memory allocations needed for a pure 2D model with 1.95 million elements in the mesh.
Look at the CPU meter. Of the 6.0Gb RAM on the PC, 5.8Gb have been consumed. Windows accounts for around 1.6Gb of RAM, so ICM is using up just over 4Gb. Now look at the GPU meter, of the 2.0Gb RAM on the GPU, 1.62Gb has been used up doing the 2D maths calculations.
As a rule of thumb, in the current edition of ICM (v3.0.1), a 2D model with 1 million elements that is passed to the GPU for mathmatical processing requires around 1Gb of GPU RAM.
If either the PC or GPU runs out of memory, the whole run will fail and you’ll get an error in the InfoWorks ICM Log file.
My advice is not to get too hung up on the details of a particular make or model of PC or GPU card. Just get yourself a high-spec PC or Server with a good GPU and an InfoWorks ICM Simulation will go just as fast as it possibly can on that hardware!