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A major release, FLOW-3D CAST v4 provides you many new tools to improve your castings, including:
- Thermal stress model to enable you to model stresses and deformations in solid and solidified parts in response to pressure forces
- Multiple improvements to your ability to model cooling channels in your dies
- Improved capabilities for modeling the generation of gasses from sand cores
- Several new numerical options that enable faster simulation times
- A new Simulation Manager function in the graphical user interface, allowing you to manage your simulations better, both before and as they run, and to visualize the progress of your simulations
- Improvements to the user interface that make setting up your simulation much easier and more intuitive
- A new state-of-the-art postprocessor, FlowSight, capable of analyzing your results in ways that were not previously possible
- Ability to run on the Linux operating system
Read more about this release in detail below.
Graphical User Interface (GUI)
- Portfolio: A Portfolio has been added to help organize groups of simulations. Simulations can be organized into workspaces allowing them to be run sequentially.
- Templates: Templates can be created from a simulation and then used to create similar types of simulations, reducing setup time.
- Runtime options: Ability to change many numeric settings while the simulation is running instead of having to terminate the simulation and start again. These options include pressure solver options, explicit and/or implicit option, general options such as number of processors.
- Calculators: Thermal penetration depth calculator (default properties are for H-13), heat transfer coefficient calculator for cooling channels (default properties are water), and metal height in the shot sleeve calculator.
- Update version or patches from GUI: This is an easy way to be informed if a patch is available and ready for download from the GUI.
- Materials database: The material database has been redone for FLOW-3D CAST to include more properties as well as better navigation and material organization.
FLOW-3D CAST v4 features a new innovative and intuitive Model Setup panel which greatly reduces the time required to create real simulations. Users are guided through the simulation setup process by the logically arranged setup panels at the left side of the Model Setup window. Elements of the casting process are entered by their actual names (e.g. mold, casting parts, filters) and appropriate physical models are activated automatically.
- GUI organization: Improved process flow.
- FAVOR™ checking: The FAVORizer is now equipped with a diagnostic tool for detecting poor mesh resolution of geometric objects defined using STL files. After running the FAVORizer to preview geometry, the results can be loaded into the graphical display window for interactive analysis.
- Interactive baffle, history probe, pointer, and valve placement: A convenient new way of defining baffles, history probes, pointers, and valves was added for FLOW-3D CAST. It allows the interactive placement of these objects based on where a probe line intersects a component. The user can then choose two surfaces of a component and graphically locate a baffle, history probe, pointer, or valve between these surfaces.
- Automesh: The ability to apply the total number of cells or the cell size to an entire mesh block will help make meshing easier to apply.
- Units: Units are now in SI (kilograms, meters, seconds). There are two options for temperature: ºC and ºK.
The new Simulation Pre-check tool allows users to quickly check their input file for common mistakes, including erroneous material properties and mesh quality issues before running a simulation.
A common problem when setting up simulations is missing or incorrect material properties. The Active simulation materials properties tab allows users to compare the material properties used in the active physical models with those of selected reference materials from the FLOW-3D Cast material database. The user is warned if required material properties are missing or significantly different than those in the database. Constant properties are compared using a bar-type graph, while temperature-dependent properties are compared using x-y plots.
Mesh Quality Checks
One of FLOW-3D CAST‘s unique strengths is how it enables users to quickly mesh geometry that can take hours or days to mesh in other programs. A new Mesh Quality Check tool automatically scans the mesh before runtime to help avoid critical errors and guides users on how to fix any meshing deficiencies. The Mesh Quality Check allows users to quickly identify:
- Large changes in cell size and aspect ratios within blocks and between adjacent blocks
- The adjacency relationship between mesh blocks (linked, overlapped, or nested)
- Missing mesh planes between adjacent mesh blocks
The FLOW-3D CAST Remote Solving tool allows customers to submit their simulations to remote computers using client-server technology. This functionality allows customers to easily access all their available hardware resources and manage their simulations in a straightforward and productive way. New features in FLOW-3D CAST allow users to leave results on remote server and to terminate all simulations in queue with one click. Also, the RunnerServer program on remote servers is now a daemon, so it now starts automatically when the system is restarted. Previously, users would have to connect to the remote system and start the RunnerServer.
- Fluid region/height display: Initial fluid regions and the initial fluid elevation are now shown on the Meshing & Geometry tab. The display properties (e.g., transparency) can be controlled with the right-click menu.
- Show All/Show Only for components: New options have been added to show/hide all components and to show/hide only the selected component.
- Color settings for baffles/probes/valves: The colors of individual baffles, probes, and valves can now be selected from a color selector.
- Improved pivot point behavior: New pivot point options are available under the View‣Pivot Point Options menu on the Meshing & Geometry tab. Users can now select between the default pivot point, which is the center of geometry, and the user-selected pivot point. Also, users can choose various visibility options for the pivot point including a new Automatic mode which only shows the pivot point when the geometry is being rotated.
- MPI inputs handled in the FLOW-3D CAST GUI: Input files generated by FLOW-3D/MP can now be opened and modified by the FLOW-3D CAST GUI.
Model Setup Improvements
- Checks on fractional and temperature input: Fractional inputs, like the fluid fraction, are checked to ensure that the specified value lies between 0.0 and 1.0. Similarly, temperature inputs are tested to ensure that the temperature is positive, since negative temperatures are not allowed by the solver.
- Highlight (i, j, k) cell in a selected mesh block: The Highlight cell option on the Meshing & Geometry tab has been expanded to allow cells to be highlighted according to their (i, ,j, k) index in a selected mesh block. This feature is useful for identifying cells reporting errors or warnings during the simulation phase.
- Option to Auto-output all available Selected data: An option is now available under the Preferences menu to allow users to automatically output all active Selected data. Users should consider this option carefully as the size of the results files can become quite large if all available Selected data is output.
- Model button:
- The tabs in the Models button have been moved from the left hand side to the right hand side to ensure they do not get hidden within the panel.
- Consistency in opening and closing of sections with the panels has been addressed by the use of arrows to open and close sections.
- Geometry button:
- Cooling channel properties are now defined on the details tab to improve ease of use.
- Motion properties are now defined on the details tab to improve ease of use.
Flow Science continues to develop its state-of-the-art postprocessor FlowSight, which is based on CEI’s award winning, EnSight. Our custom development is geared towards allowing our users to analyze and visualize their transient free-surface CFD results, using cutting edge tools to visualize iso-surfaces, slice through simulations and create flipbooks of their results that are easily sharable. Some of the new capabilities in FLOW-3D CAST that extend the power of FlowSight are described below.
- Show multiple, time-varying plots of different data types at the same time to show big-picture and quantitative data to help explain your analyses to customers of different technical backgrounds.
- Render results as a volume rather than a surface, allowing 3D images to show more information than is possible with an iso-surface.
- Calculate complex new variables, like time averages and dimensionless parameters, based on user inputs.
- Show fluid-structure interaction/thermal stress evolution results at the same time as fluid solution results.
- Save and restore settings to make postprocessing standard images and animations faster and easier.
- Make 2D slices through the domain in any direction (not just coordinate directions).
- Allow users familiar with FLOW-3D CAST to continue to use FLOW-3D post-processing until they are comfortable with using FlowSight.
Easier Access to Results
The File‣ Open dialog has been replaced with a new dialog that is considerably simpler, more powerful, and faster. It also can be configured to save commonly accessed locations, access results files on remote servers, and apply a particular context while loading a file. The new dialog streamlines loading files from different locations on different machines, giving you more time that you can spend analyzing your results. Some of the key improvements are listed below:
- Seamlessly access files from the Directory view and the Portfolio view in one dialog
- Enabled client/server functionality for Windows machines
- Significantly enhanced remote connections and ease of client/server setup
- Create shortcuts to common local/remote directories
- Apply a saved context while opening the results file
Annotations & Viewports
The Quick-text capabilities has been extended so that you can lock text to a particular viewport. This makes annotating results in multiple viewports more intuitive.
Viewports can now be split vertically or horizontally to quickly create another view of the results. Additionally, the edges of new viewports can be snapped to match those of an existing, adjacent viewport, making it easier to neatly present results.
Vortex Core Identification
The new Vortex cores tool was developed to provide a quick and reliable method of identifying recirculating regions in the flow. This is useful for detecting recirculation zones in metal castings that can lead to die erosion due to cavitation.
- Partially overlapping mesh blocks: The limitation that mesh blocks be purely linked or nested has been removed. Mesh blocks can now overlap each other in an arbitrary fashion. In areas common to several blocks, the flow equations are solved in the one with the finest mesh (based on the average cell size in the block); the solution is interpolated in all the other blocks. Partially overlapping mesh blocks make mesh generation less cumbersome and should generally result in fewer mesh blocks in a simulation.
- Boundary conditions in nested blocks: When a nested block’s boundary coincides with an external boundary of the containing block, the user can define the standard boundary conditions at that nested block’s boundary, independently of those of the containing block. Previously, a nested block always assumed the boundary conditions of the containing block.
- Solution sub-domains: The Unstructured Memory Allocation approach to addressing solution arrays on structured grids has been extended to have separate memory space (sub-domains) for the following types of numerical solutions: fluid flow, heat transfer in solid and core-gas flow. The result is a much more compact and efficient representation of the solution in memory, shorter simulation times and smaller results files. There is no input required from the user to take advantage of this development; the creation of the sub-domains happens automatically based on the geometry and model selection. There is also no loss of solution accuracy.
- Core gas model: The accuracy of the core gas model has been enhanced through the introduction of the core gas solution sub-domain, which includes not only the fully blocked cells of a core gas component as in previous versions, but also the partially blocked ones. Also, the core gas model has been SMP parallelized.
- Cooling channels: The versatility of the cooling channel model has been improved by treating cooling channels completely independent of the void model that was previously used to define cooling channels. Cells occupied by a cooling channel are still empty of solid and fluid material, but they are not included in the calculation of void regions. As a result, the reported void regions represent the actual physical voids in the problem. Also, a cooling channel can be connected to a void region and still retain its definitions and functionality as a cooling channel. Finally, when cooling channels are defined with STL files, those STL objects can be loaded in the 3D viewer and manipulated (e.g., hidden or made transparent) independently of the rest of the geometry.
- Fluid-structure interaction (FSI) and thermal stress evolution (TSE) models: The FSI model describes fully- coupled interaction between fluid and solid using an finite element approach to model stresses and deformations in solid components in response to pressure forces from the surrounding fluid, thermal gradients, and specified constraints. The TSE model describes the evolution of stresses and deformations in solidified fluid region in response to temperature gradients and solidification. Stresses can be simultaneously computed in the mold and in solidifying metal with simple options for the interaction between them. The FSI model is also useful for those interested in modeling stresses on ejector pins.
Thermal Die Cycling Model
Core and liners inserted into a die assembly and removed after each cycle can now be modeled by defining special types of components. Unlike other parts of the die that are reused after each cycle and thus retain their temperature history, the temperature of cores and liners is reset at the beginning of each cycle. At the die open stages, the die is also cooled at the parting line. The cooling at the parting line can also be modeled by defining two die components in contact.
Advances in Meshing
Partially overlapping mesh blocks
The limitation of mesh blocks to be purely linked or nested has been lifted – mesh blocks can now overlap each other in an arbitrary fashion. In areas common to several blocks, the flow equations are solved in the one with the finest mesh (based on the average cell size in the block); the solution is interpolated in all the other blocks. The user can override this order by setting the mesh block ranking by editing the prepin file and setting the variable MESH_RANK in each MESH namelist (with 1 being the highest rank). Mesh block ranking falls back to the default behavior based on the average cell size if any of the MESH namelists misses the setting of MESH_RANK. Partially overlapping mesh blocks make mesh generation less cumbersome and should generally result in fewer mesh blocks in a simulation.
Conforming mesh blocks
Instead of being rectangular, as all standard mesh blocks are, conforming mesh blocks are shaped according to the geometry. There are two types of conforming mesh blocks – cavity-conforming and solid-component-conforming. A cavity-conforming mesh block is commonly used in casting modeling, where the cavity typically requires a finer mesh than the mold. The simplest setup is to have one rectangular mesh block with a relatively coarse mesh covering the whole domain and a nested cavity-conforming mesh block for the cavity. A component-conforming mesh block is useful when resolving thin structures or thin boundary layers around solid structures. The user can select which component(s) a mesh block should conform to. By default, it conforms to all solid components within its rectangular volume. The extent of a conforming mesh block beyond the boundaries of the shape it is conforming to is defined by the input parameter OVERLAP. By default, it is equal to five times the average cell size in the conforming mesh block. Conforming mesh blocks can be nested, linked, partially-overlapping or simply stand-alone mesh blocks.
External boundary conditions in nested blocks
When a nested block’s boundary coincides with an external boundary of the containing block, the user can define the standard boundary conditions at that nested block’s boundary, independently of those of the containing block. Previously, a nested block always assumed the boundary conditions of the containing block.
- Probe-controlled termination: Solution output at a fluid or FSI probe can be used to determine simulation termination conditions, in addition to the existing criteria based on time, fill fraction or steady-state conditions. For example, a simulation can be automatically stopped when fluid pressure at a probe location reaches a predefined value.
- Restart fluid regions: A new type of initial fluid regions has been introduced to be used in restart calculations. These regions allow users to modify the initial conditions read from the restart data source files, for example, to insert a bubble or a droplet into the solution.
- History probes: History probes have been added to the interactive toolbar as well as within the GUI to allow the user the capability of monitoring parameters throughout time.
General Purpose Models
- Particle model:
- Multiple initial particle blocks: Users can define multiple initial blocks of particles, so that particles can be introduced at the beginning of a simulation at different locations and with different properties.
- Particle origin tags: Particles are now tagged according to their origin, indicating which initial block or particle source they came from. Separate tags are used for particle blocks and particle sources.
- Mass particles: Particles can now be defined by density or diameter, they can have drag and diffuse, they can stick to solids or bounce off solids, and various other options.
- Granular flows: The granular flow model has been extended from describing granular/gas mixtures to granular/liquid, or slurry, flows. This may be useful when modeling, for example, the flow of mud. The model can be viewed as a simple version of the sediment transport model without the complications of erosion and multiple sediment species. It uses the average grain properties to characterize the flow behavior of the granular material in the mixture. The forces acting on the granular media in both granular flow models, with gas and with liquid, now include dispersive pressure that arises from grain collisions in shearing flow. The additional force is a function of the friction angle which is an input parameter to these models.
- Liquid/Gas phase change: Initial and boundary conditions for the vapor/gas mixture can now be defined in terms of relative saturation. This is especially useful when modeling water vapor in air. Tabular and polynomial definitions of the P-T saturation curve and the latent heat as functions of temperature have been added to the liquid/gas phase model as an alternative to the existing Clausius-Clapeyron equation for the P-T curve and constant latent. This addition expands the applicability of the phase change model from the triple point temperature to the critical temperature. This model is useful for those who want to model core drying.
- Tabular time-dependent input: Input tables for any time-dependent property such as mesh boundary conditions, GMO motions, or mass source rates, can now be defined using external files which are then read during the simulation without copying the data into the prepin file. Unlike the tables defined directly in the prepin file where the number of points is currently limited to 500, there is no limit on the number of time points in the external tables. This allows users to define very detailed behavior of transient objects in a simulation. The impact of using the external tables on the memory and CPU usage is very minimal.
- Automatic fluid volume correction: An option has been added to automatically maintain a constant volume of fluid #1 to compensate for possible systematic volume errors due to severe distortion of free surface.
- Implicit advection: The implicit advection solver has been enhanced to allow the user to define a threshold velocity or time-step size to directly control the use of explicit and implicit approximations of advective fluxes. The goal of this addition is to speed up simulations by maintaining a larger time-step size than in a fully explicit run, but small enough (based on the user’s judgment) to resolve the essential features of the flow.
- Volume fraction cleanup: The volume fraction cleanup option allows users to force the preprocessor to close small openings between solid components that sometimes appear due to minor inaccuracies in the STL data. Barely open cells could pose problems for the stability of the flow solution, but at the same time are usually not important.
- Fluid pointers: A pointer is used to fill all open cells within an enclosure with fluid.
- Die temperatures: When using a reduced heat transfer solver inside solid components, i.e., the thermal penetration depth model or the constant non-uniform temperature option, the solid temperature in the solid region outside the active domain is now retained and can be used for post-processing and restarts. This is especially useful when running, for example, a thermal die cycling simulation with the full heat transfer solver, then a filling restart with a reduced heat transfer solver and then another restart simulation for solidification, again with the full heat transfer solver. In this case, the die temperatures obtained during the first simulation are available in the last one as the initial conditions in the newly activated die regions.
- Hydrostatic mesh boundary conditions: A hydrostatic pressure boundary condition is primarily characterized by the fluid elevation. The hydrostatic pressure boundary condition has been extended from the x and y-direction mesh boundaries to the z-direction boundaries. When fluid elevation is defined at a ZMIN or ZMAX boundary, the uniform boundary values of fluid fraction and pressure are automatically computed.
- Time-dependent void pointers: Void pointers can now be used to define not only an initial state of a void region, but also its pressure and temperature during the simulation by using tabular definitions of these parameters vs. time. This feature effectively acts as a time-dependent boundary condition for the fluid surrounding the void containing the pointer. A time-dependent pointer becomes inactive when covered by fluid or a GMO component, and is reactivated as soon as it becomes surrounded by void again. Time-dependent void pointers could be used to model heat treatment of a casting by defining the time-dependent temperature in the void surrounding the part.
- Mass source and steady-state: Mass and mass/momentum sources are now compatible with the constant-velocity flow solver, IFVELP=1. This is useful when a fully transient simulation with mass sources/sinks is run first to achieve a steady-state at which point a restart simulation is carried out with the constant velocity field.
- Component permeability input: Permeability can now be directly input to define porous properties of core gas, permeable mold and porous components. Non-Darcian permeability can also be defined for core gas and porous components (not for permeable mold components). The existing options to use sand grain size for the core gas and permeable mold, or drag coefficients for porous components have been retained.
- Flow rate at valves/vents: Gas flow rate at valves is output to the General History data catalog. This is useful for the evaluation of the effectiveness of the gas evacuation at valves.
- Output options: Output frequency of data as a function of time for history data, selected, restart, short prints, and long prints. History output is time dependent output of moving objects.