FLOW-3D v11.2 features solver performance advancements as well as refinements in the user interface.
- Expanded Particle Model
- New Dynamic Droplet Model
- New interactive geometry creation
- FSI/TSE model enhancements
- Improved GMRES convergence control
- Processing geometry improvements
- Component gap control
- FlowSight performance optimizations
The Lagrangian particle model has been completely revamped and its capabilities expanded through the addition of multiple particle classes: marker, mass, fluid, gas and void particles, each developed with specific applications in mind. Additional classes have been created to represent probes and mass/momentum sources. User-defined particle classes are designed for adding customized features by modifying the source code provided with the installation.
Dynamic droplet model for dispersed phase flows
The two-phase drift-flux model has relied on the knowledge of a constant particle size in the dispersed phase. This limitation has been removed by the addition of the dynamic droplet model that uses the concept of the critical Weber and capillary numbers to evaluate the particle sizes based on the local flow conditions. This approach is suitable for modeling dispersed phases made of gas bubbles or liquid droplets.
Mooring line model
The mooring line model has been extended to include the tearing of lines, using the Minimum Breaking Load as a new attribute of a mooring line. This development allows mooring line ends, either one or both, to move freely. Also, the requirement of at least one end of a mooring line to be attached to a moving component has been removed; the model can be used without the presence of GMO components.
GMRES pressure solver
The convergence criterion of the iterative GMRES solver, which is the default solver for pressure in compressible and incompressible flows, now provides a more robust solution for a wider range of applications, including transient and steady-state flows across different time and space scales. The new solver gives more consistent results across different hardware configurations, number of cores used and operating systems.
Geometry processing using FAVOR™
The accuracy of combining multiple subcomponents and components has been improved to eliminate the occurrence of small gaps and bumps on the surface of the geometry. This is achieved by taking into account the relative orientation and location of the fractional volumes within each computational cell.
Closing gaps in geometry
Small gaps in the geometry could result from design tolerances and variations caused by the conversion of CAD data to STL format. These gaps could just be a visual annoyance or could negatively affect the solution. The user can now request the preprocessor to close such gaps by providing the tolerance in terms of distance below which all gaps will be closed. A similar procedure can be applied to ‘thin skin’ caused by mismatches between surfaces of different components that may appear for reasons similar to those for gaps.
The conforming mesh capability has been extended so that an active computational region of an arbitrary shape can be defined. This is achieved through the use of a new type of geometry component called meshing component that defines a region in the computational domain, spanning both open and solid volumes, which a mesh block can conform to. Meshes conforming to a new type of component called meshing components are available under the Meshing tree once a meshing component has been added to the simulation.
Sediment transport and scour model
The accuracy and robustness of the sediment transport model have been enhanced by reducing the mesh-dependence of the solution and by improving sediment mass conservation. The angle of repose of packed sediment is now properly taken into account when calculating the packed bed slope.
Outflow boundaries with wave absorbing layers
The wave absorbing feature that uses geometry components of the Wave Absorbing type has been complemented by the addition of wave absorbing layers or rectangular shapes adjacent to outflow and continuative mesh boundaries. This addition greatly simplifies the definition of wave damping regions in the computational domain. The more general approach of placing wave absorbing components anywhere in the domain has been retained.
Fluid-structure interaction and thermal stress evolution models
The speed of the finite element (FE) structural solver has been improved by optimizing the data structures used in the iterative GMRES solver for stresses and deformations. The gain in performance comes at a cost in memory usage, with the actual increase a function of the number of FE nodes. A new hybrid solver has been developed that allows the user to control the amount of extra memory needed by defining it in the input file.
Graphical User Interface
Interactive geometry creation
Primitive geometry such as boxes, cylinders, and spheres can now be added to simulations by interacting with existing geometry. For example, if a user wishes to add a cylinder at the geometric center of another cylinder’s face, the Feature detect tool will automatically detect the center of the cylinder’s face when the user clicks on it and adds a cylinder there. The geometry added interactively can also be edited interactively. The icons for all geometry creation have been moved to the Geometry listbox. The icons for Baffles, History probes, Void/Fluid pointers, and Valves have moved to their respective listboxes as well.
Units on variables
Units for all variables are now displayed on dialog boxes as well as in the variable trees in listboxes. Units are only displayed if the system units or temperature units are defined for the simulation.
Boundary condition transfer
By right-clicking on any boundary in the Boundary Conditions listbox and selecting “Transfer boundaries to…”, a dialog will appear displaying all the boundaries of all the mesh blocks in the simulation. The user can then apply the boundary conditions of the selected boundary to boundaries of other mesh blocks.
Component property sorting
Component properties in the Component Properties listbox are now sorted by their Active/Inactive states. For example, component properties for physical models that are not activated are displayed below properties for activated physical models.
Raster data performance
Many improvements have been made to the underlying graphics engine to improve performance and quality. One immediate impact will be seen while working with large raster files in hydraulics simulations. Raster files with 30 million points can be handled with ease with reasonably good graphics cards (e.g., NVidia Quadro) and adequate (> 2Gb) video memory. Depth peeling has also been improved and can be turned on via the Tools menu in the Meshing and Geometry tab when an adequate graphics card is available.
Non-inertial reference frame motion
Non-inertial reference frames (NIRF) are very useful for simulating moving reference frames such as those found in satellite-based fuel sloshing problems. One of the limitations of the Analyze/Display panel is that the motion (translation and spinning) cannot be visualized. FlowSight can now display NIRF motion per the actual translation and rotation experienced by the simulation.
Distance measurement tool
A very flexible distance measuring tool has been implemented to allow distances between any objects (e.g., STLs, isosurfaces, 2D clips) to be measured.
User defined color scales
Defining custom color scales is more efficient using the custom color scale tool.
Uniformly spaced vectors on non-uniform meshes
The ability to define stretched meshes in FLOW-3D can lead to visualization issues when displaying velocity vectors. For example, if the mesh is highly concentrated in one area, a uniform vector field can be completely obscured due to the high vector density whereas in other areas the vector field may be sparse. In these cases, changing the vector display density doesn’t help since this change is applied uniformly. A new option to display the vectors on 2D clips uniformly solves this problem. This new option is available as “Show on Uniform Grid” under the Velocity Vectors option on 2D clips.
Dials and gauges
Two new annotations called dials and gauges are available under the Add quick shapes option on the right-mouse menu item on any viewport. Dials are especially helpful for displaying simulation time when the time output rate is highly non-linear. For example, consider the case of a shot-driven HPDC filling where the data output rate becomes very frequent due to the fast shot. Displaying the simulation time using a dial will more clearly indicate the rapid frame rate than simply displaying time as text.
XYZ coordinates on spline and streamline queries
The x/y/z coordinates corresponding to spline and streamline query values are now displayed in the query output dialog.