The New Art of Simulating          Multiphase Flow

A first-Class CMFD Platform for Complex Fluid Flow

TransAT Suite includes an exhaustive list of CFD & CMFD tools tailored for specific industry branches. The portfolio ranges from 1D to 3D models used in various engineering verticals, including oil & gas, nuclear energy, processing and environment.

The TransAT Suite is an advanced CFD/CMFD modelling platform including an exhaustive list of fluid flow simulation tools with emphasis on multiphase flow systems, tailored for specific engineering verticals, including oil & gas, nuclear safety issues, energy systems, chemical and process engineering and environment.


The CMFD version of TransAT©, known as TransAT Multiphase© is finite-volumes based, solving the multi-fluid Navier-Stokes equations. This version of the code uses the same meshing means as HPC (IST/BMR or BFC). It is parallelized on HPC systems using MPI. Multiphase flows can be treated using a variety of techniques and models, depending on the nature of the flow;

Topology Prediction

Multiphase gas-liquid flows can be tackled using either interface tracking methods (ITM) or phase-average models, for both laminar and turbulent flows. Specifically, the Level-Set approach, the phase-field variant and the Volume-of-Fluid methods can be employed as ITM’s. Static or dynamic angle treatment is also possible. Particle laden flows rely and the Lagrangian framework, under one-, two- or four-way coupling (granular flows).

Multiphase Turbulence

As in the HPC module, turbulent multiphase flows can in this product be tackled within both the RANS and Scale-Resolving contexts, including LES, V-LES. Statistical RANS models are used in the context of the Mixture and N-Phase techniques, which could also benefit from the versatility of scale-resolving strategies (LESS). The ITM context, however, can only be employed in connection with LES or V-LES (LEIS). The Lagrangian particle module can be used within RANS or LES

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The New Art of Simulating Multiphase Flow

Energy Systems, Process Engineering, Oil and Gas, Nuclear Safety Engineering, Environmental Engineering, Water Technology, MedTech, Microfluidics…

Advanced Turbulence

Linear Eddy Viscosity Models (EVM) : TransAT base RANS strategy relies on the k-ε model,using adaptive WF’s, low-Re models or the dynamic two-layer variant, which is more stable and cheaper than Low-Re. The model is modified to treat basic drawbacks.

Explicit Algebraic Stress Models (EASM)* : For turbulent flows featuring rotation, anisotropy, strong buoyancy effects, TransAT adopts the EASM concept, with variants ranging from the quadratic up to the quartic versions.

Algebraic Heat Flux Models (AHFM)*  : In turbulent-flow situations where the heat (or scalar) transfer does not scale with the flow motion, the base EVM models could be transcended by high-order AHFM models, including: SGGD, GGDH and AFM.

Large Eddy Simulation (LES) : The LES module built in TransAT is stable, accurate and sophisticated as to wall modelling, grid refinement, unsteady inflow conditions (using synthetic models), and schemes. The LES module resorts to various SGS models.

Very Large Eddy Simulation (V-LES) : V-LES is a compromise between efficiency and precision as to capturing turbulent flow unsteadiness and non-homogeneity, and is thus well suited for industrial problems for which LES remains computationally expensive.

Excellence in Multiphase

Interface Tracking: Level Set : The level set explicitly tracks gas-liquid interfaces on a fixed Eulerian grid, using a smooth function referring to the shortest distance to the front. The method is very well suited for free-surface problems encountered in almost all industry & environmental segments.

Interface Tracking: Phase Field : The Phase Field method is applicable to microscale  two-phase systems involving complex fluids, where the flow motion is primarily controlled by interfacial (capillary) forces.

Lagrangian Particle Tracking : Here individual particles are tracked -in the Lagrangian sense- within a flow field that is resolved on a fixed grid. The flow and temperature fields can both be affected by the presence of particles, and vice-et-versa.

Dense-packed particle systems :  Dense-packed particle systems refer to flows with mildto-high particle volume fractions. Our model accounts for particle-particle and particle-wall collision, and can thus be used for fluidized beds and various other Chemical processes.

Phase-Average: The Mixture approach : Here the transport equations are solved for mixture quantities, unlike in the two-fluid model, which substantially reduces the number of equations to be solved; a clear advantage for practical problems. The model, which can be employed with an algebraic slip model (ASM) is built within EVM (with turbulent dispersion) and LES/V-LES.

Population Balance Models with DQMOM* : Bubbly flows in chemical and process engineering involving coalescence and breakage require the representation of the size distribution function via PBM. TransAT features DQMOM as a PBM, offering better accuracy than direct multiple-class models, at moderate computational expenses.

Complex Fluids Flows

Non-Newtonian Flows : The rheology of complex fluids can be accounted for using viscoplastic models: e.g. Carreau, Power law, Cross, Bingham plastic or Herschel-Bulkley. A thixotropic model allows simulating time-dependent behaviors, as encountered in colloidal suspensions, polymer flows or muds in oil drilling.

Boiling and Condensation : Phase change heat transfer is critical for high-power density systems as well as for nuclear power plants. TransAT includes unique modelling capabilities for boiling and condensation present in these sectors.

Reactive Flows : TransAT is coupled to the Cantera chemistry library to deal with problems involving chemical reaction. Use can be made of the Eddy dissipation concept for fast chemical reactions. These models are efficient in improving conversion efficiency in various combustion applications

Solid-surface Chemical Reaction : Catalytic reaction is very important in the automotive industry, where the design of catalytic exhaust systems to reduce pollution needs advanced prediction models for complex geometries to increase surface reaction-efficiency.
TransAT includes models for multi-step reaction mechanisms on the catalytic surfaces, coupled with the conjugate heat-transfer capabilities.

Hydrate Formation & Melting :  A hydrate plug in oil pipelines may immobilize the production during weeks. Detailed 3D CMFD help anticipate the formation of hydrates, or design strategies to ensure restarting after a long shutdown. TransAT incorporates all the models to predict the formation and dissociation of hydrates.

Microfluidics Physics : Flow control in medical diagnostics and drug delivery systems is central to technology advances. TransAT is particularly powerful in predicting this class of flows; it virtually informs about tiny flow details that are otherwise impossible to detect by measurement technologies.