ANSYS Fluent’s Focus Is on User Experience

The latest release of ANSYS Fluent 17.0 has made many improvements that will help experienced computational fluid dynamic (CFD) engineers produce faster results and allow for more informed decisions early in a product’s development cycle. Additionally, these workflow, solver and meshing improvements will help CFD beginners learn the ins and outs of CFD simulations.

Tabs are arranged based on the typical stages in a simulation, and larger icons are used for common and important actions. Common settings are also available on the ribbon. (Image courtesy of ANSYS.)

Many of these changes come in the form of user experience modernizations, such as a ribbon-style tool bar. The tabs in the ribbon will be organized by the processes of a typical simulation, and icon sizes will be based on the frequency and importance of the action.

It won’t be a surprise to see many core users have some initial concerns about the graphical user interface (GUI) changes. However, William Kulp, lead product marketing manager at ANSYS, reports that once these users get the hang of it, the new navigation will reduce the number of mouse clicks by up to 12 percent.

“Fluent’s user experience has been enhanced with workflow that is easily learned by new or infrequent users, while remaining efficient, powerful and familiar to experienced users,” said Kulp. “No need to trade off Fluent’s ‘gold standard’ results for speed or ease of use. For example, preprocessing times for complex geometries were reduced 40 to 80 percent in ANSYS 17.0.”

Some of the other new navigation features include:

Availability of common settings on the ribbon
Flexible layouts
- Pop-out console
- Tab console versus task page
- Full-screen graphics window

Fluent’s Latest Solver Produces Fast and Accurate Results on Poor Meshes

Despite the poor mesh, the WFGC results are comparable to results from a good mesh. (Image courtesy of ANSYS.)

A new approach to handling warped mesh faces in the ANSYS Fluent 17.0 solver provides superior solver stability.

Kulp reports that this will allow users to produce fast and accurate results that are comparable to those from higher quality meshes.

“The new approach is available when using the pressure-based solver,” said Kulp. “This can be particularly helpful for hexagonal and poly cells with highly nonplanar faces or cell centroid outside of cell.”

Additionally, coupled solvers will now use a conservative coarsening setting as a default to assist with stability and convergence. “This is especially helpful for cases with native polyhedral meshes and/or highly stretched cells,” explained Kulp.

Near-linear scalability of the ANSYS Fluent solver. (Image courtesy of ANSYS.)

The CFD solver has also seen some high performance computing (HPC) improvements with the new release. For instance, the solver has been able to run on an impressive 129,000 cores at 90 percent efficiency. This scaling is made possible due to partitioning optimization, improved core communication and the algebraic multigrid solver.

Sliding and moving deforming meshes have also seen scalability improvements thanks to optimized algorithms for sliding interface intersections and load balancing.

“These HPC improvements are not just for extreme cases,” confirmed Kulp. “Smaller cases on HPC clusters (especially above 2,000 cores) will benefit from communication optimizations and removing bottlenecks impacting case reading and parallel building. HPC setup, including partitioning and neighborhood creation, can be done up to 30 times faster.”

ANSYS Fluent 17.0 Prepares CAD Geometry Faster

Avoid incorrect joins and improve mesh efficiency by ignoring parallel faces. (Image courtesy of ANSYS.)

Larger models and multiphysics simulations are pushing engineers to work with more complex geometries. This will translate into a difficult and time-consuming setup for the CFD model.

These large models will have many intersections and “joins” between surfaces. To ease this process, ANSYS Fluent 17.0 now allows for local “mark” and “undo” operations. These will help engineers fix faulty joins and improve their geometry efficiency.

The undo tool can roll back to the last mesh made—but no further.

Another new option is to set ANSYS to ignore parallel faces. This will help to avoid accidental intersect operations. Similarly, users can now use zone-based gap, joins and intersects.

Other CFD preprocessing improvements in ANSYS 17.0 include:

Label definition
Object creation
Part replacement
Preparation of object for wrapping
Suppression of unwanted CAD objects

Script-Based Automatic Meshing for CFD in ANSYS 17.0

Scripted automatic surface mesh. (Courtesy of Volvo.)

A major stumbling block for newcomers to CFD is the meshing of complex geometry. ANSYS 17.0 follows the simulation democratization trend by using scripted automatic meshing to simplify the meshing process.

This script-based automated meshing tool links together the SpaceClaim Direct Modeler and Fluent’s meshing algorithms. SpaceClaim then prepares the model geometry for the meshing procedure with little input from the user. Guidance on the potential of scripted meshing should be sought from your local ANSYS support team.

If a user then decides to use default solver settings, they can then fully automate the simulation process.

Application	Objective	Cell Count	Effort
Small Truck	Front-End Air Flow	46 million tet (2 layers)	1 day
Oven	Flow Rate	55 million tet (3 layers)	1.5 days
1/8th-Scale Truck and Trailer	External Aero + Front-End Air Flow	40 million hexcore	1 day
Combustor (1 sector)	External Aerodynamics	54 million (6 layers)	0.5 day
Oil Refinery	External Aerodynamics	40 million (10 prism layers)	0.5 day
Passenger Car	External Aerodynamics	80 million (2 layers) → 170 million (21 max layers—all adapted)	2 to 3 days
Motorcycle	Underhood Thermal Management	10 million (2 layers)	<0.5 day

Smart meshing and solving allows for reduced effort for simulation results. (Chart courtesy of Mike Marchant and ANSYS.)

Users will also be able to create mesh morphing and optimization constraints faster when dealing with thousands of boundary conditions. This improvement is thanks to more changes to the GUI, which allows the user to select zones easier.

Kulp reports that in one experiment with over 80 million cells and 1,962 zones, a user was able to select the target zones and set constraints in 2 seconds. Previously, this user would have spent 15 minutes on the task.

GUI improvements also speed up boundary zone point creation. The user can now specify the number of control points on the boundary instead of creating each point separately. These control points are then created automatically using binary space partitioning of the mesh.

Other CFD meshing improvements in ANSYS Fluent 17.0 include:

Native polyhedral meshes
- Two to three times faster to complete with two to three times less memory than serial polyhedral conversion in Fluent solver
- Avoids rework when tetrahedral meshes fail conversion process
Region-Based Volume Meshing
- New workflow fills regions with volume meshes faster with local settings
- Tetrahedral, hexcore and scoped prisms are supported
Distributed Parallel Prism and Serial Tetrahedral Meshing
- Partitioning the meshing using the principle of inertial axis will perform two to three times faster than serial prism generation on eight parallel nodes
Overset Mesh
- Currently compatible for:
  - Steady and transient (fixed mesh), 3D and 2D planar
  - Pressure-based coupled solver
  - Incompressible density method
  - Single-phase or volume-of-fluid (VOF) multiphase
  - Heat transfer
  - k-epsilon and SST k-ω turbulence models
- BETA in ANSYS Fluent 17.0:
  - Moving mesh
  - Compressible flow
  - VOF with surface tension
  - Pressure-far-field boundary condition
  - Workbench support
  - Pressure-based segregated algorithms

Other improvements in ANSYS Fluent 17.0 include:

Save selected results based on location (iso-surfaces, iso-clip and STL surfaces), data type and time stamps, which can reduce postprocessing and result files by up to 90 percent
Import and export geometry as STL files for better contextual geometry images

To learn more about ANSYS Fluent 17.0, follow this link. ANSYS will also be offering a webinar on Feb. 25 as part of its ANSYS 17.0 Webinar Series.

ANSYS has sponsored this post. They have no editorial input to this post. All opinions are mine. —Shawn Wasserman