ANSYS Fluent Features
ANSYS Fluent software contains the broad physical modeling capabilities needed to predict, with confidence, the impact of every fluid behavior on your product.
ANSYS Fluent is integrated into the unified ANSYS Workbench platform, which forms the foundation for the industry’s broadest and deepest suite of advanced engineering simulation technology. This easy-to-use platform provides access to bi-directional parametric CAD connections, powerful geometry and meshing tools, an automated project-level update mechanism, pervasive parameter management, multiphysics simulation management, and integrated optimization tools. As a result of these linkages, ANSYS Fluent delivers benefits that include the ability to:
- Quickly prepare product/process geometry for flow analysis without tedious rework
- Avoid duplication through a common data model that is persistently shared across physics beyond basic fluid flow
- Easily define a series of parametric variations in geometry, mesh, physics and post-processing, enabling automatic new CFD results for that series with a single mouse click
- Improve product/process quality by increasing the understanding of variability and design sensitivity
- Easily set up and perform multiphysics simulations
The bottom line: ANSYS Fluent delivers unprecedented productivity in CFD simulations, enabling Simulation Driven Product Development.
ANSYS Fluent software provides complete mesh flexibility, including the ability to solve flow problems using unstructured meshes that can be generated about complex geometries with relative ease. Supported mesh types include triangular, quadrilateral, tetrahedral, hexahedral, pyramid, prism (wedge) and polyhedral. ANSYS Workbench allows you to import your CAD geometry, prepare it for CFD use in ANSYS DesignModeler and mesh it automatically or manually with the ANSYS Mesh component. ANSYS Meshing can also automatically extract the fluid volume from a CAD assembly and mesh it using a cut cell approach, which creates non-conformal mesh composed of hexahedral elements or by using a cut tet approach, which creates meshes composed of tetrahedral elements. Both approaches support the creation of inflation layers that are critical for accurate resolution of flow in the near-wall regions.
ANSYS Fluent also allows dynamic refinement or coarsening of the mesh based on the flow solution.
ANSYS Fluent runs robustly and efficiently for all physical models and flow types including steady-state or transient, incompressible or compressible flows (from low subsonic to hypersonic), laminar or turbulent flows, Newtonian or non-Newtonian flows, and ideal or real gases.
ANSYS Fluent offers robust solvers for any application: a fully segregated pressure based solver, a coupled pressure based solver with pseudo-transient option, an implicit and an explicit density based solver.
Careful discretization is necessary to provide robust and accurate answers to the range of situations encountered in industrial CFD. ANSYS Fluent software's default high-resolution discretization delivers on both counts. The adaptive central bounded numeric scheme locally adjusts the discretization to be as close to second order as possible while ensuring stable simulation. Sophisticated numerics ensure accurate results on any combination of mesh types, including (hybrid) meshes with hanging nodes and non-matching mesh interfaces. ANSYS Fluent allows refinement or coarsening of the mesh based on the flow solution.
The vast majority of industrial flows are turbulent, so ANSYS Fluent software has always placed special emphasis on providing leading turbulence models to capture the effects of turbulence accurately and efficiently.
For statistical turbulence models, ANSYS Fluent provides numerous common two-equation models and Reynolds–stress models. However, particular focus is placed on the widely tested shear stress transport (SST) turbulence model, as it offers significant advantages for non-equilibrium turbulent boundary layer flows and heat transfer predictions. The SST model is as economical as the widely used k-ε model, but it offers much higher fidelity, especially for separated flows, providing excellent answers on a wide range of flows and near-wall mesh conditions. ANSYS Fluent complements the SST model with numerous other turbulence modeling innovations, including an automatic wall treatment for maximum accuracy in wall shear and heat transfer predictions and a number of extensions to capture effects like streamline curvature.
ANSYS Fluent also has innovative capabilities for laminar-to-turbulent transitionl. Using CFD to predict the location where the laminar boundary layer becomes turbulent is critical to improving efficiency and/or longevity of equipment in turbomachinery, aerospace, marine and many other industries. The Menter–Langtry γ–θ laminar–turbulent transition model™ gives users a powerful tool to capture various types of transition mechanisms in CFD simulation.
In addition, ANSYS Fluent provides a number of scale-resolving turbulence models, such as large- and detached-eddy simulation (LES and DES) model. The development of the novel scale-adaptive simulation (SAS) model is a highlight. This model provides a steady solution in stable flow regions while resolving turbulence in transient instabilities, such as massive separation zones without an explicit grid or time-step dependency. The SAS model has shown excellent results on numerous validation cases. It provides a good option for applications in which resolution of turbulence is required.
In ANSYS Fluent, an embedded-LES (E-LES) option allows computation of an LES solution for the subdomain in which unsteady (resolved) turbulence is required for accuracy, with a RANS model used to model the rest of the flow domain. For flows were wall effects are important but cannot be captured by a full LES simulation, the wall model LES (WM-LES) model was developed.
Optimizing heat transfer can be critical in many types of industrial equipment, like turbine blades, engine blocks and combustors, as well as in the design of buildings and structures. In such applications, an accurate prediction of convective heat transfer is essential. In many of these cases, the diffusion of heat in solids and/or heat transfer by radiation also plays an important role.
ANSYS Fluent software features the latest technology for combining fluid dynamics solutions using conjugate heat transfer (CHT) for the calculation of thermal conduction through solid materials. The solid domain can be meshed directly or modeled as a thin solid sheet using the shell model. Additional related features include the ability to account for heat conduction through thin baffles, thermal resistance at contact areas between solids and through coatings on solid surfaces.
ANSYS Fluent incorporates a wealth of models to capture all types of radiative heat exchange in and between fluids and solids from fully and semi-transparent to radiation, or opaque. ANSYS Fluent gives the user the choice of different spectral models to account for wavelength dependencies in a simulation. It also enables scattering effects to be taken into account.
Numerous CFD applications involve not just a single fluid phase but, rather, multiple phases. ANSYS Fluent is a leader in multiphase modeling technology. Its varied capabilities allow engineers to gain insight into equipment that is often difficult to probe. A complete suite of models allows ANSYS Fluent to capture the interplay between multiple fluid phases like gases and liquids, dispersed particles and droplets, and free surfaces.
For immiscible multiphase flows, ANSYS Fluent offers the volume-of-fluid (VOF) model. For multiphase applications such as spray dryers, liquid fuel sprays, continuous fiber drawing and coal furnaces, the discrete phase model (DPM) can be used. The simple DPM model allows for dilute droplet or particulate flows. For flows with denser droplets or particulates concentration, ANSYS Fluent offers the dense DPM (DDPM) model. Furthermore, accurate tracking of the collisions between large solids particles can be taken into account thanks to the ANSYS Fluent discrete element particles (DEM) model. It is also possible to simulate complex phenomena like erosion.
For interpenetrating fluids or phases, ANSYS Fluent software makes use of the Eulerian multiphase model with its separate sets of fluid equations, as well as a more economical mixture model. Both models can also handle granular flows.
The Eulerian multiphase model features a wealth of options to capture the exchange of mass, momentum and energy. This includes numerous drag and nondrag force models as well as robust models for phase change due to cavitation, evaporation, condensation and boiling. Additionally, population models allow the simulation of the effect of turbulent breakup and coalescence of different bubble sizes.
Whether simulating combustion design in gas turbines, automotive engines, or coal-fired furnaces or assessing fire safety in and around buildings and other structures, ANSYS Fluent software provides a rich framework to model chemical reactions and combustion associated with fluid flow. With ANSYS Fluent, you can use non-premixed, partially-premixed, or premixed combustion models to accurately predict parameters like the flame speed, flame location, and the post-flame temperature. These models can assume equilibrium chemistry. In situations in which the chemistry is assumed to be relatively fast, but not at equilibrium, the laminar flamelet model with presumed probability density function (PDF) offers a practical and efficient means to depict the detailed chemistry of hundreds of species without having to solve hundreds of transport equations.
ANSYS Fluent also offers innovative models such as the eddy dissipation concept, PDF transport, and stiff finite rate chemistry models as well as mature models including the eddy dissipation concept (EDC) and finite rate models. In-situ adaptive tabulation (ISAT) used in conjunction with either the EDC or PDF transport models speeds up those calculations by an order of magnitude or more.
The extended coherent flamelet model (ECFM) is suited for specific applications like internal combustion engines.
The reacting flow models available in ANSYS Fluent can be used to tackle a vast array of gaseous, coal and liquid fuel combustion simulations. Special models for the prediction of SOx formation and NOx formation and destruction are also available. The technology's surface reaction capability allows for reactions between gas and surface species as well as between different species, so that deposition and etching can be rigorously predicted. The ANSYS Fluent reaction models can be used in conjunction with the real gas model and LES and DES turbulence models.
For acoustics, ANSYS Fluent can compute the noise resulting from unsteady pressure fluctuations in several ways. Transient LES predictions for surface pressure can be converted to a frequency spectrum using the built-in fast Fourier transform (FFT) tool. The Ffowcs–Williams and Hawkings acoustics analogy can be used to model the propagation of acoustics sources for various objects, ranging from exposed bluff bodies to rotating fan blades. Broadband noise source models allow acoustic sources to be estimated based on the results of steady-state simulations.
The effect of solid motion on fluid flow can be modeled by coupling ANSYS Fluent software with ANSYS structural mechanics solutions. Using the unified user environment (ANSYS Workbench) fluid–-structure interaction (FSI) simulations can be easily set up. ANSYS Fluent FSI solutions are an Industry leader in robustness, applicability and accuracy for two-way FSI. There is no need to purchase, administer or configure third-party coupling and pre- and post-processing software.
The robust and flexible algorithm to deform a given fluid volume mesh in ANSYS Fluent tolerates even very large boundary displacements. These displacements may be defined explicitly by the user or be the implicit result of an FSI simulation with ANSYS structural mechanics software or from the rigid body solver within ANSYS Fluent. In all cases, boundary displacements are diffused into the interior volume mesh while ensuring that small or near-wall elements are deformed less. This maintains good boundary layer resolution and allows for larger mesh deformations with a single mesh topology.
In situations in which the boundary motion is more extreme and a single-mesh topology is simply insufficient to model the entire displacement, ANSYS Fluent provides options for automatic remeshing when required during a simulations
The dynamic mesh capability in ANSYS Fluent software meets the needs of challenging applications, including in-cylinder flows, valves and store separation. Several different mesh rebuilding schemes, including layering, smoothing and remeshing, can be used for different moving parts within the same simulation as needed. Key-frame mesh swapping allows swapping (automatic or manual) of a mesh during the solution according to a sequence of pregenerated meshes. Only the initial mesh and a description of the boundary movement are required. A built-in six-degrees-of-freedom solver is available for applications with unconstrained motion, including store separation, ship hydrodynamics, missile launch and tank sloshing. Dynamic meshing is compatible with a host of other models including the ANSYS Fluent suite of spray breakup and combustion models, and multiphase models including those for free surface prediction and compressible flow.
ANSYS Fluent also provides sliding mesh and multiple reference frame models that have a proven track record for mixing tanks, pumps and turbomachinery.
ANSYS Fluent delivers powerful and scalable high-performance computing (HPC) options. Parallel processing with ANSYS CFD HPC allows users to consider higher-fidelity CFD models — including large systems with greater geometric detail, (for example, a full 360-degree blade passage rather than a single-blade one) and more complex physics (such as unsteady turbulence rather than a steady turbulence model). In fact, using 64-bit technology, ANSYS Fluent can run parallel calculations on meshes consisting of a billion cells or more. The result is enhanced insight into product performance — insight that can’t be gained any other way. This detailed understanding can yield enormous business benefits, revealing design issues that might lead to product failure or troubleshooting delays. Using HPC to understand detailed product behavior provides confidence in a design and helps ensure that a product will succeed in the market.
ANSYS CFD HPC increases throughput by speeding up turnaround time for individual CFD simulations. This enables consideration of multiple design ideas and provides the ability to make the right design decisions early in the design cycle. Using ANSYS CFD HPC helps make an engineering staff, and almost any product development process, more productive and efficient.
The ANSYS Fluent technology incorporates optimization for the latest multi-core processors and benefits greatly from recent improvements in processor architecture, algorithms for model partitioning combined with optimized communications, and dynamic load balancing between processors. ANSYS CFD HPC is easy to use and works exceptionally well on a number of systems — from multi-core desktop workstations to high-end HPC clusters. Linear scalability has been shown on systems with more than 1,000 processors.
ANSYS Fluent software offers shape optimization capabilities that can automatically adjust the geometric parameters of a specific design until specified optimization goals for that design are met. Examples include optimized aerodynamics of a car or aircraft wing and the optimized flow rate in nozzles and ducts. ANSYS Fluent can also be used with optimization software from some ANSYS partners.
Furthermore, ANSYS Fluent offers ground-breaking adjoint solver technology. The adjoint solver allows you to get information about how you should modify your geometry to achieve your design goals, by modifying the mesh from within to see the effect of the recommended change. It provides information in a single simulation that is very difficult and expensive to gather using other methods. The adjoint method computes the derivative of engineering quantities with respect to the system inputs. The discrete adjoint solver is available for examining down force (for F1 applications), decreasing drag (for automobiles), and reducing total pressure drop (for ducts and pipes). The adjoint solver performs robustly and excellent scalability on large meshes of more than 10 million cells.
The detailed behavior of materials under the influence of flow conditions, such as pressure or temperature, can have a critical effect on the accuracy of CFD predictions. ANSYS Fluent software provides a wide range of material modeling options to ensure nothing stands in the way of achieving the highest fidelity solutions possible.
ANSYS Fluent comes with a rich database of material properties for a large range of liquids, gases, and solids. Both ideal and real fluid behavior can be modeled using well-established and advanced equations of state. Numerous relations are available for viscosity and conductivity variations, from Sutherland’s formula to models based on kinetic theory. For non-Newtonian fluids, an ample selection of viscosity models is provided to account for their shear-rate dependent behavior.
Should a simulation involve a proprietary material, or any other material or material property not already included in the material database, ANSYS Fluent users can take advantage of the flexibility of the user environment to easily define any number of new materials or dependencies of material properties on flow conditions such as pressure, temperature, shear-strain rate and more. Users can enter any algebraic expressions for such custom models directly in the ANSYS Fluent GUI using the simple syntax or user-defined functions.
User-defined functions are a popular option for those wanting to customize ANSYS Fluent software. Comprehensive documentation and a number of tutorials are available, as is full technical support. The ANSYS global consulting network can provide or help to create templates for the repeated setup of any equipment. Add-on modules for many special applications are available, such as PEM and solid oxide fuel cells and magnetohydrodynamics. Finally, most user operations within ANSYS Fluent can be recorded, modified and combined with ANSYS Workbench (project-wide) scripting tools for parameter/file/data management as well as design exploration.
Post-processing tools for ANSYS Fluent can be used to generate meaningful graphics, animations and reports that make it easy to convey fluid dynamics results. Shaded and transparent surfaces, pathlines, vector plots, contour plots, custom field variable definition and scene construction are just some of the post-processing features that are available. Solution data can be exported to ANSYS CFD-Post, third-party graphics packages or CAE packages for additional analysis. Within the ANSYS Workbench environment, ANSYS Fluent solution data can be mapped to ANSYS simulation surfaces for use as thermal or pressure loads. In standalone mode, ANSYS Fluent can map structural and thermal loads on surfaces and temperatures in volumes from ANSYS Fluent to third-party FEA meshes.
ANSYS CFD technology is ready for use with the ANSYS Engineering Knowledge Manager (EKM). The ANSYS EKM system addresses simulation data management challenges. It assists engineers with important aspects of simulation data management, including archiving, backup, traceability, maintaining audit trails, collaboration and IP protection. These features ensure that the knowledge gained by ANSYS CFD simulations is properly captured and ready for use in the corporate engineering process.