VOXEL-BASED GASEOUS FLUID DYNAMICS
TurbulenceFD’s simulation pipeline implements a voxel-based solver based on the incompressible Navier Stokes equations. That means it uses a voxel grid to describe the volumetric clouds of smoke and fire and solves the equations that describe the motion of fluid on that grid. For each voxel TurbulenceFD calculates the velocity of the fluid as well as several channels to describe properties like temperature, smoke density, amount of fuel, etc. This simulation process produces a voxel grid for each frame, which is cached on disk for use by the Volumetric Renderer.
INTUITIVE WORKFLOW
To setup a fluid simulation, the artist uses any type of geometric object or particle system to paint the sources of smoke, heat, fuel, etc. in space. The flow then carries along these emissions in a physically plausbile way that creates the realistic look of fire, explosions, vapor, clouds, dust and much more.
PULL ALL THE STOPS ON YOUR CPU
The biggest technological challenge in fluid simulation is the handling of the large amounts of data that a sequence of voxel grids requires. That is why TurbulenceFD’s simulation pipeline has been designed from the ground up to optimize performance. This includes a careful selection of efficient numerical methods that provide high accuracy and stability throughout the simulation pipeline. And implementing this pipeline using the latest High Performance Computing technology to optimally exploit Memory Caches, Multi-Core CPUs and advanced vector instruction sets. To the artist this means that more iterations can be run in less time, making the work with fluids more intuitive and productive.
UP TO 12x SPEEDUP ON THE GPU
Yes, twelve times! 10 minutes instead of 2 hours. And there’s a simple reason for that: today’s high-end GPUs have 8-15 times the memory throughput of high-end CPUs. TurbulenceFD exploits that. It features a hybrid CPU/GPU simulation pipeline that achieves enormous speedups. Unlike some GPU based tools, this is not just a stripped down version of the CPU simulation. All features are supported at the same quality. When GPU memory is exceeded, TurbulenceFD switches back to the CPU on-the-fly. This allows you to achieve close to real-time speeds for low resolutions and scale smoothly to high resolutions in the hundreds of millions of voxels. Instead of carefully changing parameters, sending off the simulation job and not seeing the results for hours, fluid simulations can be tweaked in quick iterations with the artist observing the effect of the changes while the simulation is processing.
PHYSICALLY BASED FIRE SHADER
Getting the colors right is critical when creating believable fire animations. You can design your color gradients manually for full artistic control. If you want realistic fire colors, the process of tweaking the colors directly can be time consuming and tedious, though. So the fire shader simulates realistic high dynamic range fire colors based on the Black Body Radiation model. This model is controlled by only two temperature values. It generates the colors real fire would have at these temperatures. But TurbulenceFD doesn’t stop you there. You may want realistic colors, but need more flexibility to tweak the enormous dynamic range that fire has. Maybe give the reds a boost, compress the dynamic range a little, or just use the generated colors as a starting point to edit the directly again.