What’s New for FreeFlow in Ansys 2026 R1

Ansys FreeFlow™ smoothed-particle hydrodynamics (SPH) simulation software is designed to simulate single-phase free-surface flows using a powerful GPU-based solver that handles large-scale simulations with millions of SPH elements.

Although FreeFlow software is one of the newest solutions in the Ansys–Synopsys portfolio, it continues to evolve rapidly, introducing innovations and enhancements with every release.

The Ansys FreeFlow 2026 R1 release introduces significant improvements to SPH fluid simulation, including the long-awaited SPH Adaptive Size capability, enhancements to Multiphysics integrations, and improvements in Performance and Usability.

Explore what’s new in Ansys FreeFlow 2026 R1 and discover how these enhancements can help accelerate innovation in your applications.

SPH Adaptive Size

One of the most anticipated capabilities in FreeFlow software is now available with the SPH Adaptive Size feature.

This feature dynamically adjusts the size of SPH elements during simulation based on user-defined criteria. Similar in concept to adaptive mesh refinement in CFD, this approach allows simulations to automatically refine or coarsen SPH elements where greater resolution or efficiency is required.

Adaptive size can be applied in several ways using the following two approaches:

• Region-based refinement, where SPH elements are refined or coarsened within a specific region of interest.
• Boundary-based refinement, where element size adapts as particles approach walls or geometric features.

Cases examples: Nozzles, flows over obstacles and hydraulic valves. ​

This flexibility allows users to maintain high resolution in critical areas, such as narrow gaps or complex boundaries, while using larger elements in less critical regions to improve computational efficiency.

In addition to improving performance, adaptive sizing can also enhance accuracy near boundaries and impact regions, making it particularly valuable for simulations involving free-surface interactions, impacts, and complex geometries.

SPH Simulation Improvements

IISPH promotion to main feature

The Implicit Incompressible SPH (IISPH) solver has been promoted from beta to a fully supported main feature in Ansys FreeFlow 2026 R1.

Following extensive validation and testing, IISPH is now the default solver for SPH simulations, while the Weakly Compressible SPH (WCSPH) solver remains available for users who require it.

Compared to WCSPH, the IISPH solver offers significant efficiency improvements. In many cases, the timestep used by IISPH can be up to an order of magnitude larger, enabling faster simulations without compromising accuracy.

IISPH simulation

Flat Plate HTC Correlation module

A new Heat Transfer Coefficient (HTC) module enables reliable heat transfer estimation using a flat-plate correlation applied directly to surfaces.

The module automatically calculates the average heat transfer coefficient for each surface triangle, simplifying thermal analyses involving fluid–structure interactions.

This capability enables FreeFlow simulations to produce results that can be integrated with advanced thermal studies and multiphysics analyses.

SPH Implicit Viscous Forces

FreeFlow 2026 R1 also introduces Implicit Viscous Forces for SPH simulations, supporting both Newtonian and non-Newtonian fluids.

This formulation improves stability and efficiency when modeling high-viscosity fluids, which were previously difficult to simulate using explicit formulations due to very small timestep requirements.

By enabling stable and efficient simulation of viscous flows, this enhancement expands FreeFlow’s applicability to a broader range of industrial fluid processes.

Variable viscosity of the fluid due to its Non-Newtonian behavior.

Periodic Continuous Injection Support

FreeFlow now supports time-periodic boundary conditions for SPH fluid inlets, enabling simulations with periodic fluid injection behavior.

This capability allows users to define:

• Injection period
• Injection duration

By controlling these parameters, users can reproduce realistic periodic flow conditions, such as pulsating injections, cyclic filling processes, or oscillating flow systems.

This feature expands FreeFlow’s boundary condition capabilities and enables more realistic modeling of time-dependent fluid behavior.

Multiphysics Coupling

Integration with Ansys optiSLang

The integration between FreeFlow software and Ansys optiSLang^® has been enhanced with the introduction of a dedicated FreeFlow node.

This improvement simplifies the setup of parametric studies, design exploration, and optimization workflows involving FreeFlow simulations.

Users can now more easily incorporate FreeFlow results into:

• Design optimization studies
• Parametric sensitivity analyses
• Reduced-order modeling (ROM) workflows

The improved integration streamlines the user experience and makes it easier to perform automated design studies involving free-surface fluid simulations.

EnSight postprocessing

FreeFlow simulation data can now be visualized and analyzed using Ansys EnSight™, providing advanced post-processing and visualization capabilities.

While FreeFlow software remains the primary environment for simulation setup and standard post-processing, EnSight enables users to perform more advanced visualization and analysis workflows, particularly for large datasets and complex fluid simulations.

Ansys EnSight provides nice visualization and post-processing for FreeFlow simulation files.

Performance & Usability

Optimization of the volumetric generation of SPH elements.

Code optimizations have significantly improved the generation of SPH elements during simulation initialization.

These improvements reduce the time required to create large volumes of fluid represented by millions of SPH elements, accelerating the setup phase of simulations.

As a result, users can expect faster model initialization compared to previous releases, particularly in large-scale free-surface simulations.

Extend SPH Flowmeters

The SPH Flowmeter capability has been extended to provide additional measurement functionality.

Flowmeters can now be used to measure average flow quantities across a defined surface, including:

• Average velocity
• Average temperature

This enhancement provides a convenient way to monitor and analyze flow behavior within SPH simulations.

With the 2026 R1 release, Ansys FreeFlow continues to expand its capabilities for high-fidelity free-surface fluid simulations. New adaptive SPH technology, improved physics models, enhanced multiphysics integration, and performance optimizations allow users to simulate increasingly complex fluid behaviors with greater efficiency. These advancements help engineers gain deeper insights into fluid dynamics and accelerate innovation across a wide range of applications.

Ansys FreeFlow™ smoothed-particle hydrodynamics (SPH) simulation software.

Learn more about Ansys FreeFlow™ software in Ansys FreeFlow Website.

JANAINA OLIVEIRA

Senior Technical / Product Publications