FLOW-3D
Optimize product designs and reduce time to market with FLOW-3D, a highly-accurate CFD software that specializes in solving transient, free-surface problems. FLOW-3D provides a complete and versatile CFD simulation platform for engineers investigating the dynamic behavior of liquids and gas in a wide range of industrial applications and physical processes. FLOW-3D focuses on free surface and multi-phase applications, serving a broad range of industries including microfluidics, bio-medical devices, water civil infrastructure, aerospace, consumer products, additive manufacturing, inkjet printing, laser welding, automotive, offshore, energy and automotive.
A uniquely powerful, multiphysics tool, FLOW-3D provides the functionality, ease-of-use and power that helps engineers advance their modeling objectives. Built for the highest level of performance, FLOW-3D seamlessly scales from standard workstations to hundreds of CPU cores on high performance computing solutions.
FLOW-3D is a powerful modeling tool that gives engineers valuable insight into many physical flow processes. With special capabilities for accurately predicting free-surface flows, FLOW-3D is the ideal CFD software to use in your design phase as well as in improving production processes.
TruVOF and Free Surface Modeling
FLOW-3D differs from other computational fluid dynamics software in its treatment of flowing fluid surfaces. The program uses special numerical methods to track the location of surfaces and to apply the proper dynamic boundary conditions at those surfaces. In FLOW-3D, free surfaces are modeled with the Volume of Fluid (VOF) technique that was first developed by a group of scientists, including Flow Science’s founder, Dr. C. W. Hirt, at the Los Alamos National Laboratory. A number of competing CFD programs claim to have incorporated a VOF capability, when in reality they implement only one or two of the three fundamental VOF ingredients. Prospective users of CFD should be aware that these pseudo-VOF schemes will often give incorrect results. FLOW-3D has all of the ingredients recommended for the successful treatment of free surfaces. Moreover, FLOW-3D incorporates major improvements beyond the original VOF method to increase the accuracy of boundary conditions and the tracking of interfaces. We refer to our implementation as TruVOF. Read more about FLOW-3D‘s TruVOF method in CFD-101
Free Gridding Separates Meshing from Geometry Construction
FLOW-3D’s basic approach to gridding combines the advantages of simple rectangular grids with the flexibility of deformed, body-fitted grids. Fixed grids of rectangular control elements are simple to generate and possess many desirable properties (e.g., improved accuracy, smaller demands on memory, and simpler numerical approximations). The approach is referred to as “free-gridding” because grids or geometry can be freely changed, each independent of the other. This feature eliminates the tedious task of generating body-fitted or finite-element grids.
The flexibility and efficiency of rectangular gridding are enhanced by the advanced features such as multi-block and conforming meshing. Linked, nested and partially-overlapping mesh blocks provide the means to effectively enmesh complex, multi-scale flow domains and concentrate high resolution in the areas of interest. Conforming meshes allow users to generate high quality grids that conform to specific geometric shapes or cavities, resolve thin structures and boundary layers, without the limitations typically associated with structured rectangular gridding. Read more about FLOW-3D‘s free-gridding approach in CFD-101
Modeling Fluid Flow in Complex Geometry is Easy with FAVOR™
FLOW-3D incorporates a special technique, known as the FAVOR™ (Fractional Area Volume Obstacle Representation) method, which is used to define general geometric regions within the rectangular grid. The philosophy behind FAVOR™ is that numerical algorithms are based on information consisting of only one pressure, one velocity, one temperature, etc., for each control volume, so it would be inconsistent to use much more information to define the geometry. Thus, the FAVOR™ technique retains the simplicity of rectangular elements while representing complex geometric shapes at a level consistent with the use of averaged flow quantities within each volume element. Read more about FLOW-3D‘s FAVOR™ technique in CFD-101
Meshing Capabilities
FLOW-3D offers a multitude of meshing capabilities that are designed to be simple yet efficient and robust in modeling complex flows. While the simplicity of meshing can be attributed to the structured mesh that is used by FLOW-3D, the efficiency and robustness is achieved by various features enabled by multi-block meshing. The use of multiple mesh blocks allows local refinement in areas of interest and significantly reduces computational resources required for a given simulation. Small obstacles, complex geometries and thin channels that are small compared to the overall domain size can be accurately resolved using one of the several multi-block meshing capabilities such as; linked, nested, conforming, and/or partially overlapping mesh blocks. Linked mesh blocks can be used only to mesh the areas of interest and limit the total number of computational cells. Nested mesh blocks can be used to enhance the resolution around an area of interest. Conforming and partially overlapping mesh blocks can be used to resolve irregularly shaped fine features with sharp changes in scale that otherwise cannot be simply resolved using nested mesh blocks. FLOW-3D also allows body-fitted finite element meshes to model Fluid-Structure Interaction. These body-fitted meshes can be automatically generated with FLOW-3D or imported from external CAD packages. All these meshing techniques gives users the flexibility to create meshes that are simple and yet efficient, thereby improving solver performance and reducing simulation turnaround time.
FLOW-3D Simulation Gallery
FLOW-3D Playlist
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This FLOW-3D simulation of a forward roll coating process captures a ribbing defect due to a high capillary number. The model incorporates the effects of surface tension and viscosity as the backing rollers draw the fluid through a 400 micron nip. The simulation is based on research described in the paper ‘Ribbing instability in rigid and deformable forward roll coating flows’ presented in the Korea-Australia Rheology Journal Vol. 22. The accurate prediction of the onset of ribbing allows for researchers to identify optimal process parameters to avoid defects.
This simulation shows a single-layer curtain coating process. FLOW-3D can be used to investigate the stability of the coating process under different process parameters such as flow rate, flow width, and substrate speed, as well as changes to the liquid’s physical properties like viscosity, surface tension, and adhesion force.
In this simulation of a multi-layer slide curtain coating process, three layers of liquid are ejected from a slot die and allowed to flow under gravity to a substrate. FLOW-3D can be used to investigate the stability of curtain coating processes under different process parameters such as flow rate, flow width, and substrate speed, as well as changes to the liquid’s physical properties like viscosity, surface tension, and adhesion force.
In this example, FLOW-3D is used to simulate drop impingement on a fibrous bed, looking at the propagation of the fluid front as it relates to surface tension, contact angle, and viscosity.
To highlight FLOW-3D’s NIRF module capabilities, a sample simulation showing the fuel sloshing in the space shuttle is set up. The space shuttle accelerates upwards for initial 25 seconds and then de-accelerates by the same amount for the next 25 seconds. After that, using angular acceleration, the shuttle rotates by 90 degrees and then continues to accelerate linearly again. It is interesting to see the complex free surface fluid motion during this complicated space shuttle maneuver. The RNG turbulence model is used to estimate the turbulent kinetic energy of the fluid.
Deformation of the combustible component (in red) of a rocket part using the Combustible objects model in FLOW-3D. The combustible object gets converted into gas creating pressure inside the combustion chamber. Pressure evolution is shown at the right in the simulation.
In this example, a pump (dark grey rectangle) in a cryogenic tank feed pipe pulls liquid oxygen from a propellant tank at a constant flow rate. As the liquid oxygen drains, a mass/momentum source (grey bar at top) is triggered by Active Simulation Control when the pressure in the ullage drops below a specified value. Pressurization is turned off when the ullage pressure rises above a specified value.
In this hydrodynamic microfluidic separation simulation, you can see particle sorting based on varying diameters. The technique works on the principle that a particle will follow a streamline. Particles with the smallest diameter (blue) get easily carried towards the top of the constriction and hence at the divergence follow the streamlines that diverge upwards. Particles with the largest diameter (green) stay their course and move towards the bottom of the constriction. Upon exiting the constriction, these particles follow the streamlines that diverge downwards.
Electrowetting is a technique used to change the apparent contact angle of a dielectric fluid under the influence of electric potential. In this example, the fluid is originally hydrophobic and beads on the surface. However, when a 50V potential difference is applied, the fluid is forced to wet the surface becoming hydrophilic.
Joule heating occurs when an electric current passes through a conducting material, such as a fluid. At a microscopic level, Joule heating is caused by interactions between moving charged particles. Additionally, if the fluid is dielectric, polarization will happen in the presence of an electric field causing fluid flow. FLOW-3D can capture all such effects, which is demonstrated by the simulation, which highlights the software‘s ability to accurately capture electro-kinetics physics.
Automotive fuel tanks hold significant fuel mass and are subject to constant vehicle accelerations and decelerations. This presents a structural issue for tank material due to the impact forces. Additionally, sloshing of fuel can cause incorrect reading or damage to measurement devices. Shown here is a simulation in FLOW-3D of fuel sloshing under acceleration plotting velocity contours. The graph shows transient force magnitude on fuel tank.
This FLOW-3D simulation depicts gear-gear and gear-oil interactions in a gear box as an example of fluid-structure interaction. The left gear possesses prescribed rotation. The two gears undergo a series of collisions with each other on their teeth causing rotation of the right gear. The right gear’s rotation is also affected by its interaction with the motion of the oil.
Simulation of a non-Newtonian, ketchup-like fluid through a nozzle. Velocity animations indicate maximum speed and steady profile through the dispenser based on upstream pressure or flow rate.
A bottle filling example uses the dynamic droplet model for highly viscous flows. These results compare three simulations that use different values of the critical capillary number, which defines the necessary shear stress for droplet breakup.
The new DEM model in FLOW-3D 2025R1 allows engineers to accurately model particle-particle and fluid-particle interactions for granular and particle-laden flows. Whether improving the cleanout rate of a cyclonic separator or testing how process conditions affect throughput, this fully coupled model supports data-driven decisions that reduce risk for high-value projects and improve system performance.