This Week in CFD

This week’s CFD news, while formatted differently, includes all the usual suspects including an article about whether CAD files are going the way of the dodo. There’s a tasty CFD application involving gelato. The application case study about cars driving backwards makes me wonder about doing CFD on a plane flying backwards. And if you’ve ever wondered why geometry modeling is to mesh generation as turbulence modeling is to CFD, there’s a paper you need to download. Shown here is a screen cap of the video of the week of supersonic flow over a cylinder by Matthias Maier.

Stream of consciousness edition. [And now you’re wondering whether previous editions actually had some structure.]

“The overall scientific objective of the BOLT project is to investigate boundary layer transition mechanisms on a low-curvature concave surface with swept leading edges at high Mach numbers (approximately five to seven).” This is from an article in the Jan-Feb 2021 issue of the AIAA Journal of Spacecraft and Rockets. Sounds like a great CFD benchmark case to me.

“[CAD] vendors will be attempting to kill files and move to databases and cloud services” is one conclusion drawn in the Beyond PLM article Who Wants to Kill the CAD File? I know a guy who has been advocating for the demise of CAD files for years and years and I understand his point. A geometry model in a CAD file is a like a rose pressed between the pages of a book – it’s still a flower but it’s dead and flat. Regardless of whether you call it a file or a database, however, you’re still faced with the interoperability challenges of representation and translation.

The latest update of Pointwise’s mesh generation software includes a native interface to the AzoreCFD flow solver. Development of the interface leveraged Pointwise’s plugin SDK which allowed Azore Software (and any user) to write the exporter themselves.

The new native interface from Pointwise to AzoreCFD makes it easy to go from mesh (left) to flowfield results (right).

“Compute geodesic distance, transport tangent vectors, and generate a special parameterization called the logarithmic map using fast solvers based on short-time heat flow,” from Geometry Central. [Not included herein solely because of the ducks. Primarily? Maybe. Solely? No.]

Illustration of various geometric computations performed using an algorithm based on short-time heat- flow. Image from geometry-central.net. See link above.

A Choice of Difference Schemes for Ideal Compressible Flow by Bram van Leer dated 09 Sep 1970.

“As predicted with simulation, the variegation is top-notch. The handmade feeling of the gelato is palpable. This didn’t just excite the consumers but the marketing team as well. Pictures of the creamy, rich, soft gelato increased sales.” A tasty story of the use of STAR-CCM+ to design a variegator for injecting sauce into gelato. [I may have shared this story already but it’s about gelato so…]

“We used modeFRONTIER in the optimization of hull shapes, foil shapes, and also to optimize sailing techniques. In all those fields modeFRONTIER allowed us to explore a much wider design space in a given amount of time than we could have done without the use of such a powerful optimization tool.” So says Martin Fischer of the Luna Rossa Prada Pirelli team about design of their new America’s Cup yacht.

“What may have escaped your attention is the availability of a new product, named Ansys CFD-Pro.” Indeed that did escape my attention in the announcement of Ansys 2021 R1 so thanks to the Leap Australia blog for the reminder. Basically, CFD-Pro is a more affordable version of CFD-Premium. But the results appear to be as good as shown below.

Comparing velocity in a pump using CFX (left) and CFD-Pro (right). Image from computationalfluiddynamics.com.au. See link above.

ICYMI, the full-paper submission deadline for this year’s International Meshing Roundtable has been extended to 05 March. Also, your note of commitment for their meshing contest is due by 16 April.

“Ever wondered how the drag coefficient changes when you drive an SUV backwards?” Heck, I don’t even understand why people back into parking spots. This question – not rhetorical – was asked and answered by the AirShaper folks for a Mercedes EQC.

Pressure clouds around a Mercedes EQC going in reverse. Image from airshaper.com. See link above.

ICYMI, Pointwise updated its free, Y+ Calculator app for iOS and Android. Every CFDer MUST [Really? Must? Wait, who am I arguing with?] have this on their phone.

“The Common Parametric Aircraft Configuration Schema (CPACS) is a data definition for the air transportation system. CPACS enables engineers to exchange information between their tools. It is therefore a driver for multi-disciplinary and multi-fidelity design in distributed environments.” I only recently became aware of this open source tool and I’m wondering how it can be used with CFD.

A video explainer of what’s new in Simcenter STAR-CCM+ 2021.1.

“We shouldn’t forget, however, that when it comes to designing efficient aerodynamics, electric vehicles offer distinct advantages.” This is actually a decent, well designed article from Audi about vehicle aerodynamics. In fact, the only thing I don’t like about the article is the fact that the image shared below is crooked.

Vehicle aerodynamics from Audi. Image from progress.audi. See link above.

Certainly you’ve seen this already because it’s sweeping teh interwebs, but use Iceberger to draw an iceberg and see how it’ll float.

VIDEO OF THE WEEK. Mach 3 flow around a cylinder. I could watch this all day.

Confronting Grand Challenges in Environmental Fluid Mechanics from Physical Review Fluids. As much as I’m curious about what I’d learn from this article, I can’t bring myself to open the wallet.

The SIAM Conference on Computational Science and Engineering will be held virtually on 01-05 March 2021. I had completely forgotten it was supposed to be held in Fort Worth.

CFD for (actually CPFD for) cement on AWS using Barracuda Virtual Reactor.

NASA’s CFD Vision 2030 Study stated that “most standard CFD analysis processes for the simulation of geometrically complex configurations are onerous.” A major factor contributing to this perception is the preparation of geometry models for mesh generation, a task deemed a “significant bottleneck” in CFD workflows. The reasons why this is so are presented in the paper Preparation of Geometry Models for Mesh Generation and CFD.

The Large Eddy Simulation Workshop on Smooth-Body Separation will be held at AIAA SciTech 2022.

Onshape Live 21 is coming up on March 11th.

Read about how meshing with Pointwise vastly sped-up the simulation of compressor casings.

CFD for testing turbine engines.

“Los Angeles-based artist Charles Gaines is celebrated for his photographs, drawings, and works on paper that investigate how rules-based procedures construct order and meaning. Working serially in progressive and densely layered bodies of works, Gaines explores the interplay between objectivity and interpretation, the systematic and the poetic.” My internet browsing came to an abrupt halt when I first saw Gaines’ painting Numbers and Trees V, shown below. The manner in which he’s superimposed a grid over a photograph and then filled it in with colored and number squares is a remarkable example of “the systematic and the poetic” as noted above.

Charles Gaines, Numbers and Trees V, Landscape #8: Orange Crow, 1989. source
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6 Responses to This Week in CFD

  1. Greg Vernon says:

    Two things:

    1) The only structure of these posts that I’m aware of is “Cool Stuff” then “Cool (Modern?) Art”
    2) Interoperability is King. Until all CNC, CMM, CAE, CAD, CAM, SLM, FDM, (keep inserting 3-letter acronyms for software and hardware) all use the same kernels and ontologies, and until all businesses in the supply chain can support interconnected cloud solutions, we’re gonna need CAD files.
    3) I’m not a CFD’er and even I have the Y+ calculator app on my phone… you just never know when you’ll need to be a hero and step in to save the day!
    4) 1 thing + 1 thing + 1 thing + 1 thing > 2 things…. maybe I should get an abacus on my phone too…

    • John Chawner says:

      Thanks for reading and commenting, Greg. I thought for a long time about how to follow-up with your interop comment. One way to avoid it is to rely on fully integrated solutions which would seem to require all CAE to fall into CAD’s gravity well. The other end of the spectrum is the so-called best-in-class ecosystem of tools for which interop is vital and which gets exponentially more complicated for multi-disciplinary sims. And when it comes to interop solutions, the old mantra rings true; good, fast, or cheap – choose two of three.

  2. A Blog Reader says:

    No need to open the wallet, thanks to Green Open Access (a Google Scholar search often gets you a PDF):
    Confronting Grand Challenges in Environmental Fluid Mechanics
    https://arxiv.org/abs/1911.09541

  3. Tom says:

    Great article. In particular the section on CAD files. As per your reply the Greg’s comment I am not sure if an entire CAE ecosystem will be the way forward (what about open source solvers who have no intention of providing a full CAE ecosystem, including CAD?). I feel a best-in-class ecosystem will be the standard in the near future and probably prevail.

    Out of curiosity, if you could change anything about CAD files (having a pointwise-biased view), what would that be? I.e. is there a way to modify existing CAD file formats to make them “less” painful or more interoperability friendly?

    • John Chawner says:

      Thanks for reading and commenting, Tom.

      If I could change one thing about CAD files I’d mandate that everyone read and write them correctly according to the standard specification.

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