Fluent Guided Meshing Workflows

• General Improvements

  • The 2D Meshing Workflow is now available from the list of meshing workflows for performing common meshing operations on 2D geometries. For details see Using the 2D Meshing Guided Workflow.

  • The Insert Drag Line button has been added to the ribbon for defining custom clipping planes within the graphics window. For details see The Ribbon.

  • Selective checkpointing is now available for disabling or enabling the writing of back-up mesh files for individual tasks within the workflow. Checkpointing for an individual task can be enabled or disabled by hovering over the task in the Workflow tab.

    

    Enabling checkpointing can be used to avoid fully restarting the workflow after clicking the Revert and Edit button for a task.

• The Watertight Geometry Workflow

  • You can now use the Use Size Field in Solids? option when using the poly-hexcore volume fill method to specify size-field-based sizing for polyhedra regions during volume meshing. This option is recommended when BOI(s) are defined that include polyhedra regions. For more details on using this option see Generating the Volume Mesh.

  • Multiple instances of the Set Up Periodic Boundaries task can now be added to the workflow before and after the Generate the Surface Mesh task. Additionally, automatic setup of multiple translational periodic conditions can now be created within the Set Up Periodic Boundaries task. For details see Setting Up Periodic Boundaries.

  • You can now insert the Add Thin Volume Meshing Controls task into the workflow to create a layered mesh within thin structures that can be combined with fill methods for volume mesh generation. In addition, this task can be utilized for meshing of stacked planar plates. For details see Adding Thin Volume Meshing Controls

User Experience

• Drag and drop copying of settings in the Outline View tree is expanded and improved. Refer to Drag and Drop, Copy and Paste in the Fluent User's Guide for additional information.

Files

• You can now choose which profiles are written when writing case profiles to a file from within Fluent. Refer to Writing Profile Files in the Fluent User's Guide for additional information.

• You can now specify whether data exported to CGNS includes the family name, using the file/export/settings/cgns-familyname text command.

• You can now specify whether Fluent exports separate CGNS zone_t for each cell zone. This behavior is controlled using the file/export/settings/cgns-separate-cellzones text command.

• You can choose to append the time-step, flow-time, or iteration number to animation image files. Refer to Animating the Solution in the Fluent User's Guide for additional information.

Solver-Meshing

• The following new predefined criteria for mesh adaption are now available for aerodynamic simulations:

  • Combined Hessian Indicator

    This criterion adapts the mesh based on an error indicator that includes the Hessian—that is, the matrix of second derivatives—of several flow fields (pressure, temperature, velocity, density, and turbulence, when each is applicable). It is suitable for use across a range of Mach numbers, and can target key areas for adaption in cases with a variety of different scales and flow phenomena.

  • Mach Hessian Indicator

    This criterion adapts the mesh based on an error indicator that includes the Hessian of the Mach number. It targets adaption for a wider range of Mach number flows compared to the Pressure Hessian Indicator, while being based on only a single scalar value for the input field, in contrast to the multiple flow fields used in the Combined Hessian Indicator.

  For further details, see Aerodynamics Adaption.

• It is now possible to easily create multiple mesh interfaces between boundary zones that do not currently overlap. This can simplify the setup for a sliding mesh simulation in which the zones begin without overlap, and then slide into positions that include overlap. (Manually Creating Many Non-Overlapping Mesh Interfaces)

• When creating non-conformal mesh interfaces, the text command for enabling adjustable tolerances (define/mesh-interfaces/auto-options/set-one-to-one-pairing-tolerance) is improved, so that you can manually adjust the length factor used in the pairing of boundary zones for mesh interfaces. This provides you with greater control, and may allow you to eliminate unnecessary mesh interfaces, produce missing mesh interfaces, or adjust the size of the interface areas. (Using a Non-Conformal Mesh in Ansys Fluent)

• When defining an auxiliary geometry definition, a new Reconstruction type is available that allows you to define the geometry by building a smooth background model based on the current node coordinates of one or more specified boundary zones. (Managing Auxiliary Geometry Definitions)

• It is now possible to delete cells that are marked by a specified cell register. (Deleting Cells)

• When defining a rigid body zone as part of a dynamic mesh simulation, you can now use a motion definition to specify the motion for the zone. A motion definition is comprised of a name, reference frame, translation definition, and rotation definition. Using a motion definition may be advantageous, as it can be simpler to set up than the alternatives (that is, a profile or user-defined function) and allows you to use expressions to define the dynamic mesh motion. (Managing Motion Definitions)

Cell Zones and Boundary Conditions

• For cases with solid zone(s) that involve perforated wall boundary conditions, you can now include the effect of conjugate heat transfer between the solid walls and the flow when the injection flow passes through the perforated holes.

• For a case that has a solid cell zone that involves solid motion with the energy equation enabled, you can now enable or disable the modeling of boundary advection at the individual boundary wall zones that are adjacent to the solid zone. Such modeling accounts for the heat that advects into or out of the domain because of the solid motion. By default it is disabled everywhere. In previous releases such boundary advection was by default applied to all of the boundary walls when the solid motion was translational and to none of the walls when the solid motion was rotational. It is now recommended that boundary advection be enabled at boundary walls where the average velocity of the solid is normal to the wall to a significant degree, and only then; this applies for translational as well as rotational motion. When you read a case created in a previous release, Fluent will automatically revise the boundary advection settings to match the new recommended practice; you can undo such changes using the define/boundary-conditions/wall text command. (Boundary Advection for Solid Motion)

Materials

• The REFPROP v9.1 database previously used by the NIST real gas models has been replaced by the REFPROP v10.0 database containing 152 fluids. (The REFPROP v10.0 Database)

  The REFPROP v7.0 database is no longer supported and is not included with the Ansys Fluent installation.

Heat Transfer / Radiation

• For the GPU solver, the Discrete Ordinates (DO) radiation model is now available.

Turbulence

• For the GPU solver, the Generic WMLES model is now available (Features Supported by the Fluent GPU Solver).

Turbomachinery

• When modeling a large pitch difference with an NPS interface, you can now minimize total pressure losses across the interface using the following text command: define/turbo-model/general-turbo-interface-settings/expert/nps-minimize-po-loss. (No Pitch-Scale interface)

• A turbomachinery performance tool is now available to evaluate various efficiencies and performance characteristics of a turbomachine. (Calculating Turbomachine Performance)

Reacting Flows

• When modeling multicomponent particles with chemical reactions, you can now specify generic values of viscosity and surface tension for the liquid urea and its by-products using the define/models/dpm/options/scr-urea-deposition/set-liquid-properties text command. (Multicomponent Particles with Chemical Reactions)

Discrete Phase Model

• When modeling multicomponent particles with chemical reactions, the Viscosity, Thermal Conductivity, and Droplet Surface Tension properties of a particle-mixture material are no longer limited to constant.

• For cases with multicomponent particles, immiscible-not-vaporizing has been renamed as none in the Evaporating Species selection list in the Set Injection Properties dialog box (Components tab).

• For cases that involve multicomponent particles with chemical reactions, you can now model thermolysis reactions in free-stream particles.

• The heat transfer coefficient models, which were previously available only for cases with inert or combusting particles, are now made available also for DPM cases that include multicomponent particles that do not contain evaporating species.

• For cases that involve the tabulated particle diameter distribution, you can now use the Interpolate Between Classes option to generate particle diameters by linear interpolation between neighboring diameter classes. (Using the Tabulated (Discrete) Diameter Distribution)

• For simulations that involve both evaporating liquid droplets and Lagrangian wall film, summary reports of evaporated mass are now fully supported. Using this functionality, you can include information about the fractions of total vapor from free-stream particles and from evaporating film in an extended summary report. This was available as a beta feature in Ansys Fluent version 2024 R1. The report/evap-mass-details-in-dpm-summ-rep text command has been renamed as report/calc-exchange-data-on-zone-types. (Evaporated Mass)

Multiphase Models

• For the two-resistance heat transfer model, the option formerly referred to as the lavieville-et-al interphase heat transfer option in the Two Resistance Model dialog box is now renamed as the time-scale option for clarity. In addition, you can now modify the time scale value.

• For Eulerian multiphase cases that involve the boiling model, you can now modify the bubble contact angle for the kocamustafaogullari-ishii bubble departure diameter model.

• The phasic wall heat fluxes for the VOF and Mixture multiphase models can now be calculated using a new approach which makes use of the linearized coefficients at the phase level. These coefficients are then accumulated at the mixture domain for correct reporting of wall heat fluxes at the wall boundaries. (Heat Transfer and Radiative Flux Distribution for Non-Eulerian Multiphase Models)

• A new postprocessing field variable, Saturation Vapor Pressure n, is now available in the Phase Interaction... category.

• For multiphase cases that involve the cavitation mass-transfer model, a new postprocessing field variable, Saturation Vapor Pressure n, is now available in the Phase Interaction... category.

Electric Potential Field and Electrochemistry Model

• For electrolysis and H2 pump cases, a new postprocessing field variable, Capillary Pressure, is now available in the Potential... category.

• For the electrolysis and H2 pump model, the following user-defined functions have been added:

  • DEFINE_ELECTROLYSIS_ECHEM_RATE: To customize transfer currents in the Butler-Volmer equations.

  • DEFINE_ELECTROLYSIS_RELATIVE_PERMEABILITY: To customize the relative permeability used in the transport equation of the volume fraction of liquid water.

  See DEFINE_ELECTROLYSIS_ECHEM_RATE and DEFINE_ELECTROLYSIS_RELATIVE_PERMEABILITY in the Fluent Customization Manual for details.

• The DEFINE_CAPILLARY_PRESSURE user-defined function has an extra argument—liquid saturation s. An example has been added to show the usage of the new argument. The existing DEFINE_CAPILLARY_PRESSURE UDFs must be updated accordingly. (DEFINE_CAPILLARY_PRESSURE)

• When using the electrolysis and H2 pump model, you can now specify total voltage and total current of a cell or stack using an expression.

• When modeling unresolved electrolysis, you can now specify the electrical conductivity for the anode and cathode catalyst layers and consider the ohmic potential loss.

  In addition, for clarity, the following parameters have been renamed and moved to different tabs in the Potential/Electrochemistry dialog box:

  Old Name	New Name	Old Tab	New Tab
  Anode Catalyst Surface Volume Ratio	Surface Volume Ratio	Electrolyte	Anode
  Cathode Catalyst Surface Volume Ratio	Surface Volume Ratio	Electrolyte	Cathode
  Anode Catalyst Thickness	Layer Thickness	Electrolyte	Anode
  Cathode Catalyst Thickness	Layer Thickness	Electrolyte	Cathode

Battery Model

• A new model, the battery venting model, is now available for simulating some battery hazard conditions. (Battery Venting Model in the Fluent Theory Guide)

• For the standalone thermal abuse model, the following enhancements have been introduced (Standalone Thermal Abuse Model):

  • You can now plot the Heating Temperature vs Temperature Profile. The Heating Rate Profile plot has been renamed to Heating Rate vs Time Profile.

  • You can now compare the temperature prediction with imported experimental data.

• The battery model can now be coupled with the multiphase model. This can be used, for example, in simulations of immersion cooling of a battery system in certain battery thermal management applications.

Polymer Electrolyte Membrane Fuel Cell (PEMFC) Model

• For transient simulations of PEM fuel cells, the ice formation model has been added. The model can predict the formation of ice inside the PEMFC device when it is started under freezing conditions. (The Ice Phase Model)

• You can now specify total voltage and total current of a cell or stack using an expression.

Fluent Native GPU Solver

• The Fluent GPU Solver can now be run on AMD GPUs.

• The following capabilities of Fluent solution mode are now supported by the Fluent GPU Solver:

  • Compressible flow at mass flow inlets and outlets.

  • Compressible flow at velocity inlets.

  • Pressure far-field boundaries.

  • Low speed compressible flow.

  • Solution controls for Pseudo time method and flow courant number.

  • Data sampling for steady statistics.

  • Conjugate heat transfer (CHT) with anisotropic and orthotropic thermal conductivity for solids.

  • Species transport with the eddy-dissipation model for turbulence-chemistry interaction.

  • Surface report definitions:

    • Standard Deviation

    • Volume Flow Rate

    • Uniformity Index - Mass Weighted

  • Volume report definitions

    • Volume

    • Mass

  • Poor mesh numerics (poor cell removal).

Density-based Solver

• A linear ramp-up of Courant number is now available for Solution Steering. (Using Solution Steering)

Adjoint Solver Module

• In previous releases, when using an expression as an adjoint observable, only single-valued scalar expressions were supported. In this release, support for combined single-value and field expressions within a binary operator has been added for defining expressions as observables.

• The Goal-Based Error Indicator predefined criteria is is now available for adapting the mesh to reduce the influence of mesh refinement on an observable as part of an adjoint calculation.

Graphics, Reporting, and Postprocessing

• You can now control the tessellation of 3D vectors in vector plots. Reducing the tessellation value leads to faster vector rendering, at the expense of the appearance of the arrows.

• You can easily measure distances and angles of objects displayed in the graphics window. Refer to Measuring Distance and Angle in the Fluent User's Guide for additional information.

• You can now visualize profile fields as a cloud of points. Refer to Viewing Profile Data in the Fluent User's Guide for additional information.

• Annotations are improved to allow for the appending of date, time, flow time, time step, and more. You can also move annotations around after they are displayed. Refer to Adding Text to the Graphics Window in the Fluent User's Guide for additional information on creating annotations.

• The new Figure 2.1: Learning and Support Ribbon Tab provides quick access to tutorials, training resources, documentation, and more.

  Figure 2.1: Learning and Support Ribbon Tab

  
  
  

• You can now directly select dashboards as an animation object from within the Animation Definition dialog box. Refer to Animating Embedded Window Dashboards in the Fluent User's Guide for additional information.

• Dashboards now support embedding plots and graphics objects without specifying a base window, thus allowing you to tile your windows such that there is no overlap. Refer to Embedded Graphics Window Dashboards in the Fluent User's Guide for additional information.

• Realistic raytracing displays now look even better with the ability to include the shadows cast by the displayed model on the environment ground. You can also lock the model's location in the environment to fine tune its appearance. Refer to Realistic Rendering Using Raytracing in the Fluent User's Guide for additional information.

Parallel Processing

• When running on Linux, a new ethernet.efa interconnect is available for Amazon Web Service (AWS) instances with the EFA interface. (Starting Parallel Ansys Fluent Using Fluent Launcher)

Fluent for Arm

• The following features are now supported when running Fluent for Arm:

  • WebUI

  • Turbo acoustics where the FFT fields are computed using the full signals

  For more details, see Running Ansys Fluent on Arm Compute Nodes.

Parametric Studies

• You can now make use of GPU resources for concurrent design point updates defined locally. See Running Locally Concurrent Design Point Updates with GPUs for more information.

• optiSLang-related features have been moved to their own category and expanded upon in the Parametric Ribbon. Now, the optiSLang Capabilities portion of the ribbon contains Data Export options for exporting data, directly opening optiSLang, or its postprocessor for further design point analysis. See Exporting Parametric Designs to optiSLang for details.

• When defining design points for use with optiSLang, you now have more options to optimize, customize, and run your designs of experiment (DOE). See Creating and Optimizing Designs of Experiments for optiSLang for details.

Simulation Reports

• Simulation reports exported to Powerpoint presentations now include breadcrumbs and descriptions for individual graphics (such as contours, plots, etc.).

Cell Registers

• When creating a cell register based on a field variable, a new Hessian approach is available from the Derivative Option drop-down list. This approach allows you to calculate an error indicator that includes the Hessian (the matrix of second derivatives) of the field variable, which can be useful when creating a cell register to use as part of mesh adaption for an external aerodynamic simulation. (Approaches For Deriving Field Values)

Expressions

• You can now change the units of in-use named expressions.

Load Managers

• The Scheduler tab in Fluent Launcher is improved to provide the following options (which were previously only available as command line options):

  • You can now specify a submission host when running under LSF.

  • When running under Slurm, you can now specify the number of node processes per cluster node and, if you have enabled the Native GPU Solver option in the Home tab, you can now specify the number of graphics processing units (GPUs) per cluster node.

  For further details, see Running Fluent Using a Load Manager.

Web Interface

• To better align with the standard desktop version of Fluent, the following enhancements have been introduced to the web interface:

  • You can now select multiple items in the Outline View by holding down the Ctrl key while you make your selection. Context menu options are available when applicable.

  • Drop-down menu options now appear properly capitalized.

  • You can now create and view plots for your named expressions.

  • Listings and categorizations of report definitions and surfaces in the Outline View have been simplified.

• Improvements have been made to Fluent's behavior when interrupting or pausing a batched/journaled simulation while the web server is running, where Fluent would have previously exited upon interrupting a journal, now a timeout period is provided.

• At the top level of the Outline View, cell zone and boundary condition listings can be displayed in various ways using the Group By context menu option where you have the choice of displaying a List View, by Name, by Adjacency (for boundaries only), or by Zone Type (the default).

• In addition to the Solution and Results aspects of your Fluent session, you now have access to the Setup of your simulation where you can interact with available simulation settings, model options, cell zone, boundary conditions, and so on. See Interacting with Your Simulation Setup for more information.

• You can now interactively move and resize the color map for results-based plots such as contours, vectors, etc.

• You can now edit multiple objects at the same time (especially useful for boundary conditions) using the Outline View and the context menu. See The Graphics Window for details.

• You can now create mirror planes using the web interface. This allows you to have a fully represent a symmetrical model by mirroring off of the symmetry plane. See Creating and Displaying Mirror Plane Objects for details.

• You can now interactively use the mouse to probe your results and visualize specific data values in specific spots. This is available by using the corresponding mode in the Visualization Arc and clicking a specific spot on the plot in the graphics window. See Editing Multiple Objects at Once for details.

• You can now select certain objects (report definitions, contours plots, etc.) in the Outline View tree and copy them to the system clipboard (using the corresponding context menu option). You can subsequently paste them into another selected object of the same type in the tree (using the corresponding context menu option). You can copy/paste such objects within the same session, or between different sessions. See The Outline View for more information.

• There is a new Theme preference that allows you to choose between the default dark color theme or a light color theme for the web interface.

• Plots have been improved to include:

  • The ability to resize the window once it has been relocated outside of its docked position (see The Plots View for details).

  • Enhancements for layout selection for multiple plots (see Displaying Multiple Plots for details).

  • The ability to create cumulative plots using the web interface.

  • The ability to plot histogram data, rather than just the ability to print data to the console.

Beta Features

• There are also some exciting new enhancements available as beta features that you may be interested in trying out. Detailed documentation is in the Fluent 2024 R2 Beta Features Manual.

Fluent Icing

Fluent Icing allows you to easily conduct in-flight icing simulations within a dedicated Fluent Application Client environment. The following additional functionality has been added in this release.

• Impact ice density model

  The impact ice density model which estimates the ice density based on local droplet impact angle and freezing fraction is upgraded to release, introducing three parameters that can be used to tune the model. These parameters are the maximum and minimum rime ice densities, and the blending function coefficient that controls the transition between the two based on the impact angle. A special handling of runback ice that forms past impingement limits where the impact angle is 0 is introduced.

• Icing with adiabatic wall boundary conditions when using particle size distributions

  Use of adiabatic walls requires running EID and vapor simulations before ice computations. Adiabatic wall option was limited to monodispersed droplet multishot icing simulations in the earlier versions, due to the unavailability of the combined vapor solution file with particle size distribution runs. This limitation is lifted by providing combined vapor solution data alongside combined droplet and crystal solution fields. To facilitate the combination of different bins with vapor, the vapor fields are now saved in droplet and crystal files and combined with the rest of the data in these files. As part of this update, vapor solution files will no longer be visible in the project view if using the Continuous (DROP3D) particle solver. Ice step will use vapor fields directly from droplet or crystal solution files. Vapor files will only be written out if running vapor only. This update enables using adiabatic walls when running with particle size distributions, since adiabatic walls require EID and EID requires vapor solution.

• De-icing enhancements

  • The unsteady de-icing feature can now display transient ice shapes.

  • Inner solver iterations are added to de-icing CHT time steps to converge the boundary conditions better, synchronizing air and ice side of temperatures and heat fluxes.

  • De-icing runs can now use a restart ice solution, to permit scenarios like running with heat-off for a long duration to accumulate ice, then use that as a restart to test various de-icing schemes.

• Anti-icing updates

  The anti-icing workflow will now start with the dry air solution to extract the HTC and surface recovery temperature. EID will be used for the HTC computation

• CFX import (beta)

  CFX .res files can be imported using the New Simulation button, similar to importing a .cas file. The mesh, the flow solution, and a limited array of settings will be imported, to be used as the air solution for particle and icing calculations. Some material properties (Cp, etc.) normally supplied as CVS files to CFX can be imported as well. This is currently a beta feature.

Fluent Aero

Fluent Aero allows you to easily explore the aerodynamic performance of aircrafts under a wide range of flight regimes, from subsonic to hypersonic conditions, all within a dedicated Fluent Application Client environment. A streamlined workflow guides you through the creation of a matrix of flight conditions or design points where single and multiple flight parameters, such as angle of attack, Mach number, altitude, etc., can vary. Most common models, solvers, and convergence settings of Fluent are tuned using the latest best practices for external aerodynamic problems and are available in Fluent Aero’s user interface. In this manner, simulations can be conducted in a quick and user-friendly environment. The full capabilities of the Fluent Solution workspace remain accessible when its session is displayed through Workspaces → Solution within the Fluent Aero ribbon. Tutorials are available to provide examples on how to conduct exploratory simulations using single and multiple flight parameters.

In this release, a broad range of features have been added and are described below.

• Parametric Post-Processing

  • The parametric post-processing feature, initially introduced as a Beta feature in 2024 R1, has been upgraded to full release in 2024 R2. It is now the default method to post-process Fluent Aero solutions and is accessible from the Results node in the Outline View. This upgrade brings several enhancements aimed at improving user experience and efficiency in analyzing CFD results. These include an easier view management system, customizable image saving options, and the ability to save all the graphics results for all the design points and to create animations with a single click.

• Aerodynamic Extraction Tool (AET)

  • The Aerodynamic Extraction Tool (AET), an automated workflow intended to extract the performance characteristics of a rotor blade, and to produce airfoil performance definition files that can be used to define the rotor performance in Fluent Virtual Blade Model (VBM) has been improved to better support large twist angles of blade sections.

• Custom Launch Script

  • A Custom Launch Script can now be used to launch the Fluent Solver connected to a simulation in Fluent Aero. This allows for complete flexibility to specify any launching option (cluster, solver, etc.) as required by a particular computing machine or in more complex computing environments.

• Reynolds Number Criterion

  • Users can now set the Viscous Model to Reynolds Number Based in the Airflow Physics panel. This option allows the specification of two Reynolds Number Thresholds, which define the three distinct flow regimes: Laminar, Transition and Fully Turbulent. A laminar flow model will be used to solve any design point in the Laminar flow regime. For design points that fall within the Transition and Fully Turbulent flow regimes, two different viscous models can be specified. In this manner, appropriate viscous models can be specified at each design point based on farfield or wind tunnel inlet Reynolds numbers.

• Turbulence Models

  • The Spalart-Allmaras turbulence model has been added as a selectable Viscous model in Fluent Aero.

  • Corner Flow Correction has been added as a selectable option for all Viscous models available in Fluent Aero that support this option.

• Aerodynamic Coefficients: Parameter Search: Stall AoA (Beta)

  • The Parameter Search feature has been expanded to search for Stall Angles of Attack associated with a particular geometry and flight condition. This search uses a hybrid methodology to identify the maximum Lift Coefficient within a range of angles of attack. This hybrid methodology applies first a Golden section method to identify a narrowed search interval, and then a quadratic interpolation method to speed-up the search of the local maximum within this narrowed interval. The Stall AoA can be subsequently used as an input to STK Aviator when defining a particular aircraft’s performance.

• Mesh Adaption (Beta)

  • A new Adaption node is available under Solution in the Outline View of Fluent Aero. This feature automatically adapts the baseline mesh of the simulation using the polyhedral unstructured mesh adaption (PUMA) in combination with the Combined Hessian Indicator. Mesh adaption cycles are used to progressively refine the baseline mesh in order to reveal the most salient flow features, shocks, wakes, etc. of your simulation, therefore improving the precision of CFD calculations. Fluent Aero’s mesh adaption is supported across multiple design points, where each design point starts with the same baseline mesh and is subsequently adapted based on that particular design point’s conditions and solution. This feature helps users to achieve accurate mesh independent solutions that capture detailed flow phenomena that may not have been possible using the baseline mesh over a wide range of conditions.

Meshing Workflows

• General Improvements

  • Minor changes have been made to polyhedra mesh behavior which will generally improve quality. This may result in some re-balancing of total cell count, with more poly-prisms being generated and fewer polys. Overall, the total cell count remains similar to that of previous releases.

• The Watertight Geometry Workflow

  • In previous releases, in the Generate the Volume Mesh task, the Normal Smooth Relaxation Factor was set to 1 by default. In this release, the normal smooth relaxation factor has been set to 100 by default, resulting in improved default prism behavior.

• The Fault-Tolerant Workflow

  • In previous releases, in the Generate the Volume Mesh task, the Prism Normal Smooth Relaxation Factor was set to 1 by default. In this release, the prism normal smooth relaxation factor has been set to 100 by default, resulting in improved default prism behavior.

Materials

• The reactions of the urea-water-deposits-air-brack mixture material in the Ansys Fluent materials database have changed to use an updated Brack reaction mechanism for urea deposits chemistry, which provides closer agreement to experimental urea decomposition curves. As a result, you may see improvements in solution accuracy of simulations that involve multicomponent particles with chemical reactions compared with previous releases.

• In the Fluent materials database, the piecewise polynomial profile of the air specific heat in the temperature range of 1000 K to 5000 K has been corrected. This will produce more accurate results for simulations in high temperature ranges.

Turbomachinery

• An enhanced version of the mixing-plane discretization has been implemented to prevent turbulence quantities from hitting limits in certain flow conditions. Typically, you may not notice major differences in results between this and prior versions. However, you can revert to the previous implementation using the following text command:

  define/turbo-model/general-turbo-interface-settings/expert/backward-compatibility/pre-24r2-mp-discretization

Turbulence

• When using the standard roughness model in combination with the following turbulence models:

  • two-equation models based on the omega-equation,

  • standard, RNG, and realizable k-epsilon models, when they are used with standard and scalable wall functions,

  • Reynolds stress models, when they are used with standard and scalable wall functions,

  the extrapolation from cell center to the wall face has been corrected and may create slight difference in the solution for velocity, temperature, omega, and epsilon.

Discrete Phase Model

• For cases that involve wet combusting particles together with the Lagrangian wall film model, the calculation of the wall-film particle thermal conductivity has been improved to account for both combusting and droplet particle materials. The previous implementation accounted only for the droplet particle material. As a result, the prediction of the wall film temperature and film boiling rate should be more accurate compared to previous releases.

• For cases with source term linearization, the enhanced source-term linearization method for the discrete phase source terms is now enabled by default. The method generally improves solution convergence, and, as a result, the convergence behavior may change slightly compared to previous releases. Settings in existing cases are respected. If you want to revert to the standard linearization method, you can issue the following text command:

  define/models/dpm/interaction/enhanced-source-term-linearization-enabled? No

Multiphase Models

• For cases that involve the Eulerian multiphase boiling model with either the Heat Flux or Coupled thermal boundary conditions at walls, the algorithm for calculating wall temperatures has been improved. As a result, the temperature distributions on walls will be more accurate compared to previous releases.

• The bisection method, which is used to determine the wall surface temperature for partitioning the wall heat flux in Eulerian multiphase boiling simulations that involve the heat flux wall boundary conditions, has been improved. It now incorporates a more accurate algorithm for generating initial guesses for the initial minimum and maximum values of the wall surface temperature range. This will result in more accurate solutions for some cases, such as those with relatively high wall heat flux.

Field Variables

• The Cell Wall Distance field variable (in the Mesh... category) is no longer available if the case file does not contain any walls.

Parallel Processing

• For Windows with more than 64 logical cores, the default MPI is now changed to Microsoft MPI. The default remains Intel MPI for all other cases (that is, Windows with less than 64 logical cores and Linux). To specify an MPI, you can use the MPI Types drop-down list in the Parallel Settings tab of Fluent Launcher or use the -mpi= command line option.

User-Defined Functions (UDFs)

• The CX_Message utility is no longer supported and should not be used as it may cause the Ansys Fluent session to hang infinitely. Instead of CX_Message, use the Message utility for printing data to the console. See Message for details.

• A new argument, const char *solver, has been added to many Fluent built-in functions. Typical examples of the affected functions are Scalar_Derivatives(...) and Scalar_Reconstruction(...). To update your user-defined function (UDF), follow these steps:

  1. For any Fluent built-in functions used in your UDF, check to see if the argument list has changed and update the UDF source code accordingly. Use the "rp-global" string constant (in double quotes) as an argument for the new call parameter (unless you are instructed otherwise).

  2. When compiling your UDF, carefully check and address all compiler warnings.

Fluent Materials Processing

• • The number of processors used by the workspace solver has been increased from 2 to 4 processors.

  • Mesh objects created by the workspace no longer use generic naming conventions (mesh-1, mesh-2, etc.) by default. The new default is to use the topological names found in the mesh file. The behavior can be changed using Preferences. See Setting Preferences for Fluent Materials Processing in the Fluent Workspaces User's Guide for details.