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Computational Fluid Dynamics (CFD)

With OnScale Solve’s easy application of flow and pressure boundary conditions to any applicable CAD model, we put the flow in your CFD workflow. OnScale Solve provides top-tier result visualizations with a backend powered by cloud supercomputing, without you paying top-dollar. 

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Get answers to common questions about Fluid Analysis in OnScale Solve


What are OnScale’s CFD capabilities?
Fluid simulation in OnScale Solve is currently targeted at internal flow, providing accurate prediction of the behaviour of fluids within a bounded volume.  Applications include flow through:

  • Ducts and pipes
  • Plenums
  • Vessels
  • Heat exchangers
  • HVAC systems
  • Manifolds
  • Exhausts
  • Microfluidic devices
  • Vascular systems


Does OnScale Solve use OpenFOAM?

Flow simulation in OnScale Solve uses LBM-based CFD technology developed by our partner Lexma.  Solve does not use OpenFOAM at this time.


Is there a way to refine the mesh near the wall?
At OnScale, we believe meshing should be automated as part of a trouble-free simulation workflow.  We’ve put a lot of development effort into optimizing mesh generation for reliable accuracy at minimum cost so that customers generally don’t have to worry about it.  When using CFD in OnScale Solve, an important input to the mesh generation is the “Characteristic Length”, which should be set to the effective hydraulic diameter of the flow cross-section.  When the cross-sectional area varies, the minimum value should be used to ensure adequate mesh density throughout the flow.  The mesh density within the model can be further varied using the Mesh Quality selection (Very Coarse, Coarse, Medium, Fine, or Very Fine).  In OnScale Solve CFD it is not necessary to refine the mesh near the wall because the correct near-wall fluid physics is automatically modeled by the simulator.


Can simulation data be exported for post-processing on my local computer?
Yes, the simulation data can be exported from OnScale Solve for further post-processing as described in this webinar here.


What type of solver is OnScale Solve based on? How do I choose the right turbulence model?

OnScale Solve CFD uses a flow simulator based on the Lattice Boltzmann method (LBM). Turbulence modeling is handled automatically.


Can you restart a simulation based on a prior one?

Not currently, but running simulations initialized from the results of a previous simulation is on our roadmap. Please subscribe to receive our product updates.


Can you set up surface integrals over an area and calculate mass flow rate or force on a wall?

Yes, you can do this using the integrated Jupyter Notebook capability. Simulation results data are generated in VTU format, including the data fields required to calculate area-integrated flow rates, forces, or other quantities of interest.


How is convergence decided? Are there residuals or the equivalent to that?

OnScale Solve CFD uses a time-explicit method and does not require evaluation of residuals or something equivalent. Time convergence, i.e reaching a statistically converged state sufficient for reliable measurement of observables, requires setting the simulation Duration to a suitable value of physical time. Time convergence can be assessed using the data output to the ‘probes.csv’ file in the POSTPROC folder of the completed study, which can be accessed with the integrated Jupyter Notebook functionality in the Results section. This file contains pressure and velocity magnitude values vs time for 10 random points within the solution domain – plotting this data gives a good indication of whether time convergence was achieved. Automated time convergence detection, and automated stopping of a simulation once convergence is reached, is a feature on our roadmap; please subscribe to receive our product updates.


Are there other visualization methods available, like streamlines?

Not at the moment, but streamlines and isocontours are coming soon to Solve. Note the simulation data can be downloaded for use in commonly used post processing software on your local computer. Please subscribe to receive our product updates.


What’s next in the roadmap for OnScale Solve CFD capabilities?

We’re hard at work to improve the overall user experience and provide new features. Our immediate roadmap includes input support for periodic boundary conditions, volumetric flow rates, and  output support for requesting flow rates at specific locations. For up-to-date information, please subscribe to our product updates