Volume rendered simulation of combustion chamber shows temperature variations AND gradient.
To produce a more realistic image, STAR-CCM+’s CFD solver is moving past the traditional surfaces (boundary, sections or iso-surfaces) to renderings inside of a flow-field via volume rendering.
With this technology, temperature variations and temperature gradients can be visualized in one diagram. For instance, in the simulation of a combustion chamber we not only see the temperature based on color; we see that more opaque areas have a high gradient while transparent areas have low gradients. In comparison, the iso-surface render makes this determination impossible.
The volume rendering process works by turning volume elements into voxels. The model domain is divided in the transformation from a mesh to a resampled volume voxel. This voxel can have qualities like opacity, lighting and color to give the simulation the added detail.
However, this added information means that trade-offs must be made between quality and resample times with respect to processor power. This has added a new voxel to cell ratio parameter which engineers must get used to if they wish to perform a volume render. Voxel domains can be refined in a similar fashion to mesh refinement. For example, in the combustion chamber there are more voxels near the blades for added detail.
Though volume rendering isn’t new, it traditionally has been limited to media outlets such as film and video games due to this complex data management. However, STAR-CCM+ is bringing this rendering tool to an engineer’s laptop.
Iso-surface rendered simulation of combustion chamber.
Other developments in the new Star-CCM+ version include improving the simulation of water droplets in multiphysics and implementing cost functions into the adjoint solver. The adjoint solver allows for sensitivity analysis with only one simulation.
Source and Images Courtesy of CD-adapco 1, CD-adapco 2