FLOW-3D v9.2 - New Features
Version 9.2 of FLOW-3D offers faster solutions, decreased computer resource requirements, unique physical modeling and increased accuracy in solving free-surface problems.
The following summary highlights the key benefits offered in FLOW-3D Version 9.2, headlined by our one-of-a-kind General Moving Objects (GMO) Collision Model whose fluid structure interaction capabilities allow moving objects to interact with other solid objects in a realistic fashion; increased speed with Unstructured Memory Allocation and Locally Implicit Advection; and an enhanced graphical user interface and more powerful visualization tools.
This computational fluid dynamics simulation depicts
log transport in a spillway. Motion of the logs is
dynamically coupled with water flow. Floating logs
collide with each other and the with the wall, step and
bottom of the channel. Front and back views of the
collision shown above.
Fluid Structure Interaction - General Moving Objects (GMO) Collision Model
A unique model among CFD software, the GMO Collision Model gives users the ability to model collisions of multiple moving rigid bodies with other moving and fixed objects. The new collision model extends the current 6-DoF GMO model and is valuable for all application areas of FLOW-3D. Exciting new modeling possibilities include debris flows, opening and closing valves and counter-meshing gears.
Collisions are computed for coupled-motion GMO components when coming in contact with other moving or stationary objects. Collisions can also occur between the moving objects and walls or symmetry boundaries of the computational domain. Collisions can be perfectly elastic, partially plastic or completely plastic. Object surfaces can be smooth or rough, allowing existence of friction at the point of contact during collision. Continuous contact between moving objects, such as sliding, rolling and sitting of one body on top of the other, is modeled through a series of rapid, small-amplitude collisions, called micro-collisions.
Click here to view more simulations using the GMO model. Also, see our description of this new feature in the Spring 2006 FLOW-3D News and in the presentation given at the 2006 FLOW-3D World Users Conference (Proceedings available).
Simulations now run faster than ever using UMA, where solution arrays are allocated only on active parts of the mesh, saving valuable computer resources. Large problems that were not possible to run on common desktop workstations can now be solved. Combined with the multi-block meshing, UMA enhances meshing flexibility and increases solution accuracy. Irregular computational domains can now be defined even in a single-block environment by using domain-removing components. Casting problems requiring very large grids to resolve small or thin-wall regions benefit most from this new approach.
to manually deactivate open cells where desired. The example above depicts how this applies in the case of a simple simulation of flow down an inclined slope.
A new implicit advection technique has been incorporated into FLOW-3D, breaking a long-standing tradition of using only explicit advection methods. The implicit treatment of advective fluxes is applied selectively in cells where it speeds up the calculation without affecting the accuracy. Users benefit from the new method by being able to obtain solutions up to 50% faster.
With explicit techniques, the high speed flows
at the gates in an HPDC filling can lead to very
small time steps. The new locally-implicit
advection available in Version 9.2 made this
filling problem run 70% faster.
When the implicit option is activated, then the time-step size is allowed to exceed the Courant stability condition for flow away from free surface. Courant criterion is still applied at the free surface to maintain the accuracy of the VOF method. A new output variable called “Courant number” is calculated and stored for post-processing when the implicit advection option is activated. It serves as an indicator for the degree of implicitness in each cell.
GMRES Pressure Solver
The convergence of the GMRES pressure solver in multi-block meshes has been greatly improved. Due to its efficiency and scaling on parallel SMP machines, GMRES has become the solver of choice in most flow problems, from MEMS to hydraulics. The GMRES Pressure Solver has had two major enhancements: (a) a greatly improved convergence for multi-block grids and (b) the ability to utilize the inter-block boundary type coefficient for better conservation of volume.
Elastic Stress Model
Surface displacements have been added for post-processing. The displacements are computed as a scalar product between the free surface unit normal and the displacement vector and are useful mostly as a color variable for 3D fluid fraction iso-surface plots. Displacements can also be visualized as vectors in 2D and 3D plots.
This is an extensive addition to enable modeling of mass/momentum sources like vents or thin pipes. Mass/momentum sources can now be created directly without requiring a customization. Sources can be time dependent in flow rate and velocity. And, they can move spatially at a user defined velocity. These sources are intended to represent various objects such as flow from a pipe, air duct or nozzle. Their shapes can be square, rectangular, circular or elliptical.
Many New GUI Features:
- A new Pause button allows the solver to be paused to release the solver license token, release the CPU and swap the executable out of memory (may be machine-dependent)
- New, intuitive mouse modes let users rotate, zoom and move objects and meshes.
- Twenty levels of un-do and re-do the viewpoint gives users increased flexibility.
- Initial fluid regions and their complements can be displayed.
- Simulation units set from the main menu are automatically written to the project and results files.
Powerful New Visualization Options:
- Plotting settings are automatically saved and can be retrieved in each new FLOW-3D session.
- Plot displacement vectors for the Elastic Stress model in 2D and 3D display
- Users can now display sharper images of geometry in their FLOW-3D results. Both STL files and geometry created in FLOW-3D can be transformed in many ways: changing the colors of objects, applying transparency and moving, rotating and scaling transformations.
View the featured highlights in Version 9.3.