HELYX-Coupled is an extension module for HELYX and ELEMENTS featuring the following solver components:

  • Fully implicit, pressure-based, block-coupled solver for incompressible and compressible flow applications in the sub-sonic, transonic and supersonic regimes.
  • Fully implicit, density-based, block-coupled solver for compressible flow applications in the sub-sonic, transonic and supersonic regimes.

The coupled solver technology in HELYX-Coupled has been extensively tested and validated to simulate a wide range of devices, including vehicle external aerodynamics, projectiles, turbomachinery, etc. The block-coupled approach provides considerable benefits over equivalent segregated solvers in terms of convergence speed and robustness, making this add-on a must when turnaround times are critical.

Why HELYX-Coupled?

While standard segregated type solvers make use of pressure correction algorithms to achieve a converged solution, the block-coupled solvers in HELYX-Coupled solve the continuity, momentum and energy equations simultaneously (in a single matrix system) to deliver convergence speeds up to 10 times faster. The HELYX-Coupled solvers also show linear scaling with number of cells and excellent parallel efficiency in HPC systems, exhibiting faster performance than similar commercial CFD solvers in the market.

Additionally, the block-coupled solvers delivered with the HELYX-Coupled add-on module make use of the exact same physical models, boundary conditions and ancillary tools available in HELYX and ELEMENTS for segregated solvers, making it really easy to switch between segregated and block-coupled solutions.


The block-coupled solvers in HELYX-Coupled are fully supported in HELYX-GUI and incorporate the following features as standard:

Single-phase, steady-state and transient flows.
Incompressible flows (Ma < 0.3) with pressure-based solver.
Compressible flows (0.3 < Ma < 5) with density-based solver.
Characteristic (non-reflective) boundaries for transonic and supersonic flows.
RANS, URANS, DES, LES turbulence.
Dynamic mesh motion with extended ALE formulation.
Porous media regions, MRF, GRF and other volumetric sources.


Single channel water pump simulation using HELYX-Coupled (Courtesy of Grundfos)


Wall shear stress on F1 car surface calculated with HELYX-Coupled (geometry courtesy of Samuel Silva).


Karpouzas, G.K. A Hybrid Method for Shape And Topology Optimization in Fluid Mechanics. Engys Ltd. s.l. : NTUA, 2018.

Darwish, M, Sraj, I and Moukalled, F. A coupled finite volume solver for the solution of incompressible flows on unstructured grids. Journal of Computational Physics. 2009.

Council for Scientific and Industrial Research in South Africa (CSIR). High Speed Aerodynamic (HiSA) Solver. GitLab Project Page. [Online] https://hisa.gitlab.io/.

Heyns, J.A., Oxtoby, O.F. and Steenkamp, A. Modelling High-speed Flow Using a Matrix-free Coupled Solver. 9th OpenFOAM Workshop. 2014.


Want to Buy?

The solvers in HELYX-Coupled are released under the GNU General Public License for the benefit of the end-user. For further information about HELYX-Coupled features, availability and prices, please contact us today or speak to one of our local sales representatives.

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