Dynamic Fluid Body Interaction|
Keeping to a rigorous four monthly release schedule, the latest release again broadens the scope of application through the addition of a “Dynamic Fluid Body Interaction” model. Unlike traditional CFD software, which is typically limited to simulating the motion of a body along some prescribed path, the STAR-CCM+ V3.04 DFBI model enables engineers to easily simulate the fluid induced movement of a body, for everything from a tanker listing under heavy seas to an aerodynamic body tumbling in free fall.
“The significant advantage of our new DFBI model is that it allows the fluid induced motion of an object to be predicted in six degrees of freedom, with no additional effort from the user, compared to performing a simple steady state simulation of flow past the same body,” says Jean–Claude Ercolanelli, CD-adapco’s VP Product Management. “The meshing process for a DFBI simulation is identical to that for a simple non-moving calculation and the DFBI model accomplishes its task without invoking the complex and time-consuming re-meshing schemes used by other CFD tools.”
At each time-interval, STAR-CCM+ V3.04 calculates the forces and moments acting on the body by automatically integrating the pressure and frictional loads before calculating the acceleration, velocity and displacement in six degrees of freedom. Rather than using complex mesh distortion or interpolation across sliding boundaries, the DFBI model works by translating and rotating the entire computational domain in response to the fluid induced load. STAR-CCM+ V3.04 then updates the flow field for the new body position and, iterating this procedure over time, calculates the trajectory of the body.
A complete tool for marine applications
DFBI is useful for any simulation in which an unrestrained object moves in response to fluid excitation. However, it is particularly useful when combined with STAR-CCM+ V3.04’s powerful free surface modeling capability, to simulate the behavior of floating vessels such as boats. For large amplitude motions, such as a container ship navigating heavy seas, the DFBI model can be used to simulate wave slamming, capsizing, wave-piercing, water-entry and green water effects.
STAR-CCM+ V3.04 also includes an automatic wave generator, which is fully integrated into the GUI, allowing users to generate waves using just a few simple parameters. The DFBI solver can also be used for marine applications in which a vessel’s running attitude depends on the pressure field around the hull. Running in steady-state mode the DFBI model will calculate the vessels actual position in the water for a given boat speed, automatically calculating sinkage, heel and trim.
Each new release of STAR-CCM+ contains raft of new features and enhancements that help to increase productivity while reducing analysis turnaround times. The automatic hexahedral mesher now has the ability to refine cells in specific directions allowing greater control of cell count without compromising accuracy, extremely useful for aerodynamics and free surface simulation. A new surface offset tool has been added to the Surface Preparation GUI to ease and speed-up the handling of complex and poor geometry. Building on the advanced turbomachinery functionality introduced in the last release, indirect topological interfaces for multi-stage turbines may now be modeled where each stage has a different pitch. Multi-band thermal radiation in participating media has also been implemented in STAR-CCM+ for the first time, allowing the radiation properties to vary with wavelength.