ICCFD10, Barcelona

PSA: Abstracts for ICCFD11 are due on 18 Feb 2020!

Amazing destination conference opportunity in Maui, Hawaii

Every two years, the International Conference on Computational Fluid Dynamics is held in a different iconic city across the globe. ICCFD conferences begun in 2000 as the merger of “Numerical Methods in Fluid Dynamics (ICNMFD), and the International Symposium on Computational Fluid Dynamics (ISCFD); which had been running since 1969 and 1985, respectively.” According to the ICCFD homepage.

In early 2018, I submitted two abstracts and was lucky enough to be invited to present a poster on “Scalable HPC Building-Block for Multi-Disciplinary Systems” and complete paper on “Unified Geometries for Dynamic HPC Modeling”. I’ve published a few papers before, but this felt like a new experience; here I was submitting for peer review intimate technical details on the inner workings of some of my original innovations. In the past it was always part of academic group. I worked for two months to bring together my 20-page paper, leaving the presentation until the week of the event…

Pretty familiar experience for most engineers — those minutes leading up to a big presentation…
This balanced tree approach to geometry type taxonomy permits nice inheritance and functional polymorphic optimizations. It is also really interesting to resolve the characteristic similarities and differences between types. There are embedded levels of orthogonality in many spaces. This yields a complete solution space to address all analysis challenges.
In the red, it says that across types we found on order: 50X span in memory usage, 60X span in IO usage, and about 20X speedup when running on GPU vs CPU. Not bad!
Now that the work part is done, I can now look around…
Barcelona is an absolutely gorgeous city, and maintains its own special timeless charm. This is pretty much a typical back alley.
Many interiors have simply stunning craftsmanship and taste. Visual inspiration all around!

The lovely coastal city of Sitges, Spain!
The world-famous multi-century construction project, Sagrada Familia.

Food. Okay let me just say that perhaps my favorite element about Spain was the food. Fresh, flavorful, and affordable. Tapas around great, but we made a point to try many different types of restaurants ranging from known tourist spots to tiny spots that only open for a few hours in the late evening to serve a couple families. Honestly, almost every place we tried had something special about it and several of them we just had to come back for a second or third time. Really, we should have taken more food pictures.

To make up for it, here are a few treats:

Hope to see you at ICCFD11 Summer 2020 in Maui, Hawaii!

Spaceport Cup 2019

Once a year a pilgrimage occurs to the mecca of amateur and commercial rocketry, nestled in the desert north of Las Cruces New Mexico. University-sponsored teams from around the world converge on Spaceport America to demonstrate their rocket design, analysis, building, and launching skills… one of the greatest defining moments in their collegiate careers. Teams can compete in certain competition categories, targeting altitudes of 10,000ft and 30,000ft. However, some teams elect to attempt flights beyond — to 50,000ft and up to 100,000ft using solid, hybrid, and liquid propulsion systems.

This facility is uniquely positioned just west of Whitesands Missile Range, so it is possible to obtain waivers to fly all the way to space on a regular basis, if required… as are the plans of emerging spaceflight companies Virgin Galactic and others.

It turns out the event was so popular this year that there were zero cars available for rent in the El Paso region. I was able to bum rides for the duration for the trip and made some profound new friendships. The morning of the first flights, we made it out to Spaceport America before sunrise — morning weather is best for launches. The largest building in the complex is currently VG’s new hangar, dubbed “The Gateway to Space”. This quick shot from our car doesn’t do it justice; it’s an incredibly-inspiring facility that represents the emerging commercial spaceflight industry.
Here’s a view of the Gateway from the Spaceport Operations Center. The state of New Mexico is investing heavily into emerging space industry. Personally, I think these lands will be of significant importance moving forward.
Here’s the Gateway to Space from the back (2.5 mile runway behind the camera). It was such a treat to meet Spaceport CEO Dan Hicks and his staff. He’s one of the nicest and most competent leaders I’ve encountered in the industry. He’s assembled an incredible team to move things forward, methodically and safely…and inspiring innumerable ppl along the way.
The Spaceport supports propulsion testing and vehicle flight test operations, spanning solids, hybrid, and liquid engine efforts. Designated areas and modern infrastructure will position them for long-term success. However, they must also be prepared and trained in emergency response. Spaceport America has its own specially-equipped fire and police department on duty 24/7. This new fire truck is one of their arsenal with all modern sensing and life-saving technologies. They work closely with local and federal authorities.
It’s no easy task to host several thousand students out in the desert for most of a week. There was a designated area for general spectators as well as a restricted area for rocketeers, judges, and volunteers. I’m very grateful to Spaceport America for granting me access to all areas.
A dry heat was sustained at over 100 degrees most of the day and dust storms tend to pick up as the day progresses. Numerous facilities and comforts were brought in for water, food, shade, and first-aid. Almost everyone was struggling against the heat, but the event did a very good job of providing rest areas and reminding attendees to keep hydrated. The food trucks and icies were especially popular. The people were the best part.
Over 120 university teams and numerous aerospace companies participated. It was a delight to walk the rows of tents and talk to each team. The international participation was strong (with more than 17 countries represented) and there was a feeling it was special for everyone to interact, share, and support. While this was a competition, the demeanor was one of cooperation and friendship.
Many well-known universities had a presence. Most had to drive for several days to get their equipment and rocket to the launch site. For many, this was the capstone project for their university major.
17 teams from Canada participated in the competition. It’s superb to see such comradery between students across borders. Perhaps the UN should be replaced by rocket clubs… 🙂
University of Washington came in full-force with their awesome liquid rocket project. They would later be crowned the winner of the 2019 Spaceport Cup!
Switzerland also had several teams with some great innovations and craftsmanship. When I launched rockets about a decade ago, active control systems were extremely rare. Nowadays, teams like these can reliably deploy airbrakes and other control surfaces to help hit their target altitude.
I was delighted to also meet a few teams from India. Not only did they muster the time and resources to put together some amazing projects, I think it was super special they made the long journey (which is not easy with rocket components).
This picture does not do it justice. Iowa State University’s rocket appeared to have some of the best aerodynamic designs I’ve seen in rocketry. In particular, their forward control canards were very close to optimized shapes with professional fabrication and positioned for (what appeared to me) proper CG-CP correlation and potential control-ability?! For the expected supersonic flight regime, the vehicle proportions seemed close to optimal.

It was such a treat to be able to meet with so many of you! Honestly, I think you’re all winners and given that the worst injuries that I heard of were heat exhaustion and a sprained ankle, I would say congratulations for being a part of a world-class rocket event! Hope to see you next year!

Ad Astra!

‘the space show’ called me E.T.

That’s the pot calling the kettle black!

Thank you for the kind words and interest! We had a BLAST at Space Access 2019!


Xplicit Computing gets discussed from 46:21 – 52:20 . Here’s the segment set to some of the presentation material:

Space Access 2019

The most interesting space tech conference you’ve never heard about.

Turns out crazy comes in many different forms:

Lady and Gentlemen gather on the last eve of Space Access 2019. We were actually kicked out of the hotel bar because we were too excitable. On several occasions, I was approached with the pickup line “want to see my rocket/engine?” (See below)
I was pretty busy piloting my own XCOMPUTE spaceship. It is powered by high performance computers and good vibes. We were there celebrating our official product launch! Check out emerging capabilities and special offers with our partners R Systems and Rescale.
Hosted by ERPS and SAS, these events run long and hard, all day. It’s exhausting to soak it all in…each talk is so different and interesting…it feels terrible when you must pick and choose. On Thursday night I had a brief 15 minutes slot to introduce the new platform.

Here most’s of the video: (though there wasn’t any music in real life, just me talking)
This short musical montage looks back at our development over the last 5-6 years (from a graphical UI perspective) as we have iterated toward the current enterprise platform. The early 2D FDM prototype codes were truly impressive and beautiful. We’ve taken a detour into more complex 3D FVM, FEM, and other essential methods first before expanding once again. We think this new architecture will give us 100x the power and flexibility of our early numerical codes. Further, we’re looking into the future of advanced machine design and operating systems.
An incredible spectrum of people were in attendance, spanning advanced amateurs, university researchers, aerospace start-ups, and even notable legends such as directors for major US agencies such as DARPA.

The event was structured in a way to maximize people connections to facilitate business in space sectors. The first day was focused on practical space entrepreneurship and business activities. The second day was more ambitious trans/cis-lunar and deep-space exploration. The last day was high-risk high-reward concepts with a keen eye on energy/power systems. Probably more than 50% of attendees held an engineering degree and/or industry experience.
After another long day of talks we were excited to get an exclusive update from SpaceIL founder and recent attempts at landing their Beresheet spacecraft on the lunar surface. Huge inspiration to all, despite the terrible connection and A/V issues.
This is how we have fun and put our bench-top rocket fuel pumps to use when not on exhibit or moving hypergols. Explosions were controlled, mostly. Two ranging margarita parties fueled some of the leading rocket scientists to get belligerent and bash scramjets. Because we’re all so agreeable…
Going into the event I didn’t really have anything good to show. Long story short, the night/morning before I set up my computer in my hotel room and ran a 6.7M element CFD with the A/C directly into that Titan-Z going at full blast. I saved 1/10 of the 10,000 iterations to yield 350 GB of data in about 4 hours. (Each frame is about 350 MB)

towards sustained hypersonic flight

What comes after the Space Shuttle?

New Glenn? Falcon??

I believe something more radical is on the horizon…

Summary: a modernized X30 National Aero-Space Plane with advanced computing under the hood.

About six years ago, I was fortunate to receive hundreds of hours of guidance from the CFD chairman at Boeing (now at Blue Origin). As my startup’s acting VP of Research, he helped us establish technical requirements for a new simulation platform for next-gen systems. He set us on a path, and I worked to bring it all together, pulling from a spectrum of experiences at JPL, Blue Origin, and Virgin Galactic…

Why does hypersonic flight require a new engineering approach?

Banner image, courtesy https://en.wikipedia.org/wiki/Specific_impulse


By definition, “hypersonic” means much faster than sound. There does not appear to be a formal demarcation between supersonic and hypersonic, but design philosophies start to deviate markedly as kinetics take over. At sufficient speed and conditions, traditional compressible flow theory becomes inaccurate due to additional energy modes of excitation, storage, and transmission (that were not included in the original model). As specific kinetic energy approaches molecular bond energies, a distribution undergoes dissociation, inhibiting chemical reformation reflected in further-limiting reaction progress (“Damkohler numbers”). A transition occurs as radiation dominates thermal modes. Plasma density increases as free stream energy density approach valence electronic Gibbs potentials. At some point, you can’t extract net positive work because combustion doesn’t progress (until recombination outside the engine).

For air, I’d say hypersonic phenomena onset around M~6. Very few vehicles to date (or planned) have such capabilities, obviously.

However, I think it is within our technological grasp to cruise at Mach 15+ with the right configuration and engineering approach, enabling point-to-point travel and booster services for deploy-ables and satellites.

In time, I intend to demonstrate a clear pathway forward. First we must understand the basic principles and underlying processes…


Perhaps close or slightly worse than current commercial high-bypass turbo-jet engines, but certainly worse than future hydrogen turbo-jets!

However, a marked performance improvement over traditional hydrogen-oxygen rocket performance since not only does the air-breathing vehicle not have to carry its own fuel, but it can control the effective specific impulse by varying the ratio of bypass (air) to heat input (fuel).

To move beyond traditional liquid-fueled rockets for high-speed trans-atmospheric flight, we can extract more thrust-per-Watt out of an air-breathing engine by including more air (“working fluid”) in the propulsive process at a slower jet speed (difference between engine outlet and inlet velocities). We essentially spread the jet power to maximize fuel efficiency (“effective specific impulse”) and to have jet outlet velocity match free-stream speed to maximize jet kinetic efficiency. (Ideally, once ejected, exhaust would stand still in the reference frame of the fluid. However this is not possible at very low speeds due to minimal mass flux through engine generating minimal net thrust, albeit at very high efficiency! At high Mach numbers, there isn’t enough delta-v in the exhaust to keep up with vehicle speed, and a gradual drop in thermodynamic efficiency is expected.)

Example everyone can observe: this is why commercial jets have big engines with big bypasses so that majority of the thrust comes from the fan, rather than the core engine flow. I think nowadays the ratio is something like 8:1. The exhaust velocity is roughly sonic at Mach 0.85 cruise — all to maximize fuel economy — the driving economic factor for air-travel and a significant portion of your airfare. Not to mention ecological impact. Image courtesy https://en.wikipedia.org/wiki/General_Electric_GE90

The average kinetic energy of the vehicle scales as the square of its speed, while the power required to sustain flight scales as the cube.

What does this mean about powered vehicles that fly very fast?


As vehicle power-density scales as speed cubed, propulsion starts to dominate the design of the vehicle in hypersonics. The vehicle becomes a big flying engine as M->25, and the project schedule and funding should reflect this. Based on flight profile and lift requirements, a linear “wave-rider” design may be considered vs more practical annular layout (which also is more efficient at carrying large thermal-stress loads and propellant storage). Fuel density remains important, but not as much as net specific energy density.

Sub-cooled liquid hydrogen is used as fuel and coolant, and if pressed above supercriticality, has insane heat capacity — but at a cost of varying density (and Nusselt number used in regen cooling analysis). Both active and passive cooling strategies are required to offset vehicle and engine heat transfer. An open cycle is unacceptable to overall performance, so boundary layer coolant (BLC) must be injected on leading surfaces and ingested / combusted (as part of a turbulent shock-detonation inlet). Combustion takes place in specialized sub-sonic burners before being mixed with the primary flow as part of a closed staged-combustion cycle. Liquid oxygen is supplemented to the combustors for take-off and LEO injection.

Engine length becomes an impediment in smaller vehicles (such as those encountered by any research/test program) due to finite combustion reaction time, requiring longer characteristic chamber length to ensure relatively-complete combustion (Damkohler numbers close to one). Net chemical power extraction is balanced against thermal and drag impediments, so the systems must balance all these and resolve rate reacting large eddy simulation (LES), as physical testing will have inherent limitations to replicate and measure combustion environment. Simulations are used for analysis and optimization and to characterize transfer functions to be applied as the machine’s advanced onboard control system.

Although a hypersonic compressor and diffuser does not use rotating turbomachinery (per excessive thermal-stresses), supporting cooling and fluid control systems remain a large-scale systems engineering challenge. The technical scope is akin to a nuclear power plant that can fly and requires multiples modes of operation. Structural engineering must make no assumptions regarding thermal and acoustic environments as the vehicle will pass through many regimes, expected and off-nominal. Quantifying dynamic load environments require experiment or flight experience, as computing resources to resolve turbulent micro-structures scale as the Reynolds number to 9/4 power, more than square of speed!

To have any hope to getting this right, we must have a very strong concept and technology basis. We need a good initial vector and structured yet flexible approach…so defining the problem by systems and subsystems provides the exact encapsulation and recursive definition required to be infinitely interchangeable and expandable (only limited by computing resources). These tools must be intuitive and powerful as to fully-leverage parallel computing so analysis doesn’t continue to be the bottleneck:

From a project cost and schedule perspective, it is imperative that the concept and its infrastructure be a suitable architecture, as more than 2/3 of project costs are locked-in by the time the first design decision is made. I’ve heard officials from DARPA claim, from their experience, that problems costs 1000x more to fix while in operations than if caught in pre-acquisition stages.


There’s obviously a lot of competing factors in advanced aerospace and energy systems. To integrate these different domains (fluid, thermal, mechanical, electronic) we need an alternative to the current isolated unidirectional “waterfall” engineering process. We need a unified HPC platform everyone can use to integrate systems, not just fluids or solids.

To take steps beyond theory into practice — to actually conceptualize, design, analyze, and build these systems, we need some amazing software and sustained discipline across many teams. Realistically, the problem must be approached with a strong systems framework and restraint on exotics. (“Can I personally actually build this?”) I’ve been participating in various AIAA and peer-review conferences over past years, and there is certainly some impressive work out there. I think the CREATE suite from the DoD has taken a real but ambitious approach to give the military turn-key analysis tools. However, I haven’t seen many commercial or academic firms with their eye (or checkbook) on the systems challenge of next-gen engineering — let alone an architecture that not only demonstrates multi-disciplinary functionalities now (CFD, FEA, etc) while remaining relevant to future computing.

I pulled away from the aerospace industry to dedicate just under 20,000 hours to this software infrastructure, collaborating with a few bright graduate researchers at Stanford, MIT, and the Von Karman Institute. We made hundreds of thousands of code contributions across more than two-thousand commits. We burned through a small fortune of friends and family investments and leveraged technology to work more efficiently towards decadal objectives of NASA. Things, we have reason to believe, few are attempting. It is now getting exciting…

Despite funding obstacles, we’ve broken through major barriers and are ready to apply our new advanced engineering platform to new projects — leveraging modern software machinery (C++14, OpenCL) and processing hardware (CPU, GPU, FPGA). Our integrated engineering environment provides end-to-end capabilities for such grand challenges. We can now build simulations out of different systems and algorithms and dispatch them to any processor. Aerospace is only the first use case.

You’ve really got to be a fearless generalist to take on something like this. But you’ve also got to be able to dive deep into key areas and understand the process on first and zeroth principles. Many fields of mathematics and technical practice, concentrated into an applied real-world problem. Since you can’t rely on books for answers to new questions, we must inquire the fundamental laws and be cognizant of our human constructs and assumptions made therein.

Is it possible to optimize against physics while also providing a practical engineering path?

I’ve pondered such quandaries for many years, but now I think I have a clear path. Over the next few years I hope to demonstrate and share what I can on this blog.


P.S. All this talk about jet engine thrust reminds me of this time a senior engineer at Blue Origin emailed a challenge question to the company along the lines of – if force is the integral of pressure times area, what parts of a jet engine are most responsible for its net thrust generation?

Do you know?

It appears most of the company did not. I took a stab:

It’s the pressure differential across the bypass compressor blades, probably followed by the central jet exit (and its compressor blades and internal cowling).