Remembering Stephen Jurczyk

It seems just like yesterday that I was at NASA Langley working for a short time under then Director Stephen G. Jurczyk. He passed away just recently on Thanksgiving of 2023. He helped propel my career in the later stages of my time at Langley. One thing that I appreciated a lot about Stephen Jurczyk was that he came up through the organization as an engineer. Not all NASA administrators or SES are engineers nowadays. I appreciated this fact about him, because I felt that he could understand the needs of the research staff of the center. Reading books like Engineer in Charge gave me a deep appreciate of the history of NASA, and also gave me a viewpoint that the leaders of NASA should be first and foremost learned people of science. Unfortunately, this is not so much the case today. I’m hopeful that future leaders of NASA come from backgrounds in engineering especially, instead of political appointees with degrees in economics or finance.

Another important lesson is that one should try and depart love ones with kind words, because one never knows when will be the last time someone says goodbye.

Toward Exascale Computation for Turbomachinery Flows

Citation: Yuhang Fu, Weiqi Shen, Jiahuan Cui, Yao Zheng, Guangwen Yang, Zhao Liu, Jifa Zhang, Tingwei Ji, Fangfang Xie, Xiaojing Lv, Hanyue Liu, Xu Liu, Xiyang Liu, Xiaoyu Song, Guocheng Tao, Yan Yan, Paul Tucker, Steven Miller, Shirui Luo, Seid Koric, and Weimin Zheng, “Toward Exascale Computation for Turbomachinery Flows,” Gordon Bell, High Performance Computing, Networking, Storage and Analysis (SC ’23). Association for Computing Machinery, Article 4, 2023. pp. 1-12. DOI: 10.1145/3581784.3627040 [Open Access Link via DOI]

The screenshot of Q-criteria iso-surface colored with velocity magnitude, with background contoured by pressure gradient to visualize the shock wave and pressure propagation.

Abstract: A state-of-the-art large eddy simulation code has been developed to solve compressible flows in turbomachinery. The code has been engineered with a high degree of scalability, enabling it to effectively leverage the many-core architecture of the new Sunway system. A consistent performance of 115.8 DP-PFLOPs has been achieved on a high-pressure turbine cascade consisting of over 1.69 billion mesh elements and 865 billion Degree of Freedoms. By leveraging a high-order unstructured solver and its portability to large heterogeneous parallel systems, we have progressed towards solving the grand challenge problem outlined by NASA, which involves a time-dependent simulation of a complete engine, incorporating all the aerodynamic and heat transfer components.

Updates on Tsien

I was able to find additional interesting pictures for my page on Tsien. One is with Adolf Busemann, father of swept wings and German / NASA Langley Scientist. Others are interesting like his home in Beijing. I’m currently reviewing a biography, and will make a note when finisihed.

National Air and Space Museum’s Journey Toward 2025

Appearing next month in the NASA Alumni Newsletter.

Walking on the Washington, D.C. Mall is an inspiring experience for all citizens. One might be inspired by the many memories and great institutions of our American people. Nestled as one of the most visited museums of the world is the National Air and Space Museum, just southwest of our Nation’s Capital. The museum had a partial reopening on October 14, 2022, with the west wing of its building unveiling eight new and renovated galleries. However, the east wing remains closed for renovation. The next phase of the renovation, which includes the east wing, is scheduled to be completed in 2025.

I have traveled to D.C. and have seen the entirety of the previous exhibits on display. Like many in the aerospace profession, every time I go to D.C. I visit the museum. I love seeing the new exhibits. The best part of the museum is not the exhibits themselves, but watching people from all over the world who are amazed. Here, people say, ‘we did that?’ often expressing surprise at what was accomplished in the approximately last 120 years of flight.

What is new in the western third of the museum includes:

  1. Destination Moon: This exhibition features numerous icons of space history, such as the Apollo 11 command module Columbia and Neil Armstrong’s Apollo 11 spacesuit, both of which have undergone extensive conservation in recent years.
  2. Jackie Cochran’s T-38: On display is a Northrop T-38A Talon flown by aviator Jacqueline “Jackie” Cochran, who set eight world records for speed, altitude, and distance flying in 1961 with this T-38.
  3. Walking On Other Worlds: An interactive experience that provides a seven-minute “tour” of seven different celestial bodies, offering an immersive media exhibit with a nearly 360-degree screen.
  4. Nation of Speed: A collection of vehicles built for speed.
  5. Diverse Stories: A broader story of aviation and space, like Neal Loving’s red Loving WR-3 air racer, a parachute used by Georgia “Tiny” Broadwick, and airline uniforms worn by pioneering women pilots like Emily Howell Warner, Cynthia Berkeley, and Bonnie Tiburzi.

I encourage everyone to plan a D.C. visit to see the grand opening of the entire renovated museum in 2025. It is important to make advance entry reservations before you go. A limited number of same day entry reservations can be made on their website. It is entirely free.

Armstrong’s Lunar Suit (Photo – Miller).
View of the new west gallery from the second floor (Photo – Miller).

Split-Step Simulations to Assess the Effects of Atmospheric Boundary Layer Turbulence on the Dose Variability of N-Waves and Shaped Booms

My former student, Dr. Alex Carr, along with Dr. J. Lonzaga, who are both of NASA Langley Research Center, and myself published an article on the propagation of sonic boom through the turbulent atmosphere.

Abstract: The effects of atmospheric boundary layer turbulence on the loudness variability of a sonic boom N-wave and shaped boom are examined with split-step simulations. The shaped boom is representative of a design iteration of the NASA X-59 aircraft. Inhomogeneous atmospheric boundary layer turbulence is generated in the computational domain by a Fourier synthesis method. The N-wave and shaped boom are propagated through turbulent fields representing eight different convection levels measured at the NASA Kennedy Space Center and the NASA Armstrong Flight Research Center. Probability density functions of the formation of caustic regions along the propagation direction are computed from the N-wave results, and a parameter to collapse the caustic PDFs that accounts for both fluctuation intensities and length scales is proposed. Statistical results concerning loudness metric variability are presented, and the standard deviations of several metrics are shown to collapse across different convection levels of turbulence for small nondimensional propagation distances. The loudness metric distributions are observed to be well approximated by a normal distribution for a given range of propagation distances, and become increasingly skewed as distance increases. A model function for the dose variability is proposed, and the function parameters are found to be related to the convection level of the turbulence. The model for the dose variability distribution is compared to simulation data that were not used to find the regression parameters of the model. At several nondimensional propagation distances, agreement is observed between the model and the simulation data. These results indicate that the model may be suitable for providing quick estimates of noise dose variability in the primary carpet region across a wide range of atmospheric boundary layer conditions.

Carr, A. N., Lonzaga, J. B., Miller, S. A. E., “Split-Step Simulations to Assess the Effects of Atmospheric Boundary Layer Turbulence on the Dose Variability of N-Waves and Shaped Booms,” The Journal of the Acoustical Society of America, No. 571, 2024. pp. 1-28. DOI: 10.1016/j.jsv.2023.118118 [Link via DOI]

Academic Freedom at Florida CLAS

One of my colleagues informed me about a website at the University of Florida, hosted by the College of Liberal Arts and Sciences. The website provides information about academic freedom, and I’m impressed by the college’s effort to create the website. It addresses fundamental questions that people often have about academic freedom, tenure, and other significant university-related topics. The content is presented in a manner that is accessible to everyone, and it includes citations and links for further reading and research. I’ve included the link to the main content below.

  • Academic freedom is a set of norms and practices that guides faculty in the pursuit of research and teaching, as well as matters of shared governance, and as citizens to serve a democratic society for the common good.
  • Academic freedom includes the freedom to teach, discuss, question, and explore freely according to the standards of our disciplines.
  • Shared governance and tenure are important components to support academic freedom.
  • Students have a right to freedom in learning, including freedom to question and discuss material introduced in a course.

“The essentiality of freedom in the community of American universities is almost self evident. No one should underestimate the vital role in a democracy that is played by those who guide and train our youth. To impose any straitjacket upon the intellectual leaders in our colleges and universities would imperil the future of our Nation…. Scholarship cannot flourish in an atmosphere of suspicion and distrust. Teachers and students must always remain free to inquire, to study and to evaluate, to gain new maturity and understanding; other wise our civilization will stagnate and die.”

U.S. Supreme Court, Sweezy v. New Hampshire(opens in new tab), 1957

was designed and implemented over 80 years ago to act as a fundamental pillar supporting academic freedom. It allows faculty to pursue the search for knowledge and to educate students in a manner that is independent of and not beholden to any special interests. Tenured professors report their teaching, research and service activities annually and are evaluated at the department level along with all other faculty.

Source: Academic Freedom at Florida CLAS [Link –]

Fall 2023

Who would have thought that 7 years go by so quickly at the University of Florida. This year I am teaching introduction to computational fluid dynamics. The last time I taught it was before COVID in the fall of 2020. I am working on a new design program for nozzles. I am basing it on the original method of characteristics, but integrating boundary layer theory, source plane theory for transonics, and trying to build upon some of the previous programs published by NASA.

Talking Oak I spoke

ONCE more the gate behind me falls;
Once more before my face
I see the moulder’d Abbey-walls,
That stand within the chace.
Beyond the lodge the city lies,
Beneath its drift of smoke;
And ah! with what delighted eyes
I turn to yonder oak.

For when my passion first began,
Ere that, which in me burn’d,
The love, that makes me thrice a man,
Could hope itself return’d;

To yonder oak within the field
I spoke without restraint,
And with a larger faith appeal’d
Than Papist unto Saint.

For oft I talk’d with him apart,
And told him of my choice,
Until he plagiarised a heart,
And answer’d with a voice.

Tho’ what he whisper’d, under Heaven
None else could understand;
I found him garrulously given,
A babbler in the land.

But since I heard him make reply
Is many a weary hour;
’Twere well to question him, and try
If yet he keeps the power.

Hail, hidden to the knees in fern,
Broad Oak of Sumner-chace,
Whose topmost branches can discern
The roofs of Sumner-place!

Say thou, whereon I carved her name,
If ever maid or spouse,
As fair as my Olivia, came
To rest beneath thy boughs.—

‘O Walter, I have shelter’d here
Whatever maiden grace
The good old Summers, year by year,
Made ripe in Sumner-chace:

‘Old Summers, when the monk was fat,
And, issuing shorn and sleek,
Would twist his girdle tight, and pat
The girls upon the cheek.

‘Ere yet, in scorn of Peter’s-pence,
And number’d bead, and shrift,
Bluff Harry broke into the spence,
And turn’d the cowls adrift:

‘And I have seen some score of those
Fresh faces, that would thrive
When his man-minded offset rose
To chase the deer at five;

‘And all that from the town would stroll,
Till that wild wind made work
In which the gloomy brewer’s soul
Went by me, like a stork:

‘The slight she-slips of loyal blood,
And others, passing praise,
Strait-laced, but all too full in bud
For puritanic stays:

‘And I have shadow’d many a group
Of beauties, that were born
In teacup-times of hood and hoop,
Or while the patch was worn;

‘And, leg and arm with love-knots gay,
About me leap’d and laugh’d
The Modish Cupid of the day,
And shrill’d his tinsel shaft.

‘I swear (and else may insects prick
Each leaf into a gall)
This girl, for whom your heart is sick,
Is three times worth them all;

‘For those and theirs, by Nature’s law,
Have faded long ago;
But in these latter springs I saw
Your own Olivia blow,

‘From when she gamboll’d on the greens,
A baby-germ, to when
The maiden blossoms of her teens
Could number five from ten.

‘I swear, by leaf, and wind, and rain
(And hear me with thine ears),
That, tho’ I circle in the grain
Five hundred rings of years—

‘Yet, since I first could cast a shade,
Did never creature pass
So slightly, musically made,
So light upon the grass:

‘For as to fairies, that will flit
To make the greensward fresh,
I hold them exquisitely knit,
But far too spare of flesh.’

Oh, hide thy knotted knees in fern,
And overlook the chace;
And from thy topmost branch discern
The roofs of Sumner-place.

But thou, whereon I carved her name,
That oft hast heard my vows,
Declare when last Olivia came
To sport beneath thy boughs.

‘O yesterday, you know, the fair
Was holden at the town;
Her father left his good arm-chair,
And rode his hunter down.

‘And with him Albert came on his.
I look’d at him with joy:
As cowslip unto oxlip is,
So seems she to the boy.

‘An hour had past—and, sitting straight
Within the low-wheel’d chaise,
Her mother trundled to the gate
Behind the dappled grays.

‘But, as for her, she stay’d at home,
And on the roof she went,
And down the way you use to come,
She look’d with discontent.

‘She left the novel half-uncut
Upon the rosewood shelf;
She left the new piano shut:
She could not please herself.

‘Then ran she, gamesome as the colt,
And livelier than a lark
She sent her voice thro’ all the holt
Before her, and the park.

‘A light wind chased her on the wing,
And in the chase grew wild,
As close as might be would he cling
About the darling child:

‘But light as any wind that blows
So fleetly did she stir,
The flower she touch’d on dipt and rose,
And turn’d to look at her.

‘And here she came, and round me play’d,
And sang to me the whole
Of those three stanzas that you made
About my “giant bole;”

‘And in a fit of frolic mirth
She strove to span my waist:
Alas, I was so broad of girth,
I could not be embraced.

‘I wish’d myself the fair young beech
That here beside me stands,
That round me, clasping each in each,
She might have lock’d her hands.

‘Yet seem’d the pressure thrice as sweet
As woodbine’s fragile hold,
Or when I feel about my feet
The berried briony fold.’

O muffle round thy knees with fern,
And shadow Sumner-chace!
Long may thy topmost branch discern
The roofs of Sumner-place!

But tell me, did she read the name
I carved with many vows
When last with throbbing heart I came
To rest beneath thy boughs?

‘O yes, she wander’d round and round
These knotted knees of mine,
And found, and kiss’d the name she found,
And sweetly murmur’d thine.

‘A teardrop trembled from its source,
And down my surface crept.
My sense of touch is something coarse,
But I believe she wept.

‘Then flush’d her cheek with rosy light,
She glanced across the plain;
But not a creature was in sight:
She kiss’d me once again.

‘Her kisses were so close and kind,
That, trust me on my word,
Hard wood I am, and wrinkled rind,
But yet my sap was stirr’d:

‘And even into my inmost ring
A pleasure I discern’d
Like those blind motions of the Spring,
That show the year is turn’d.

‘Thrice-happy he that may caress
The ringlet’s waving balm
The cushions of whose touch may press
The maiden’s tender palm.

‘I, rooted here among the groves,
But languidly adjust
My vapid vegetable loves
With anthers and with dust:

‘For, ah! my friend, the days were brief
Whereof the poets talk,
When that, which breathes within the leaf,
Could slip its bark and walk.

‘But could I, as in times foregone,
From spray, and branch, and stem,
Have suck’d and gather’d into one
The life that spreads in them,

‘She had not found me so remiss;
But lightly issuing thro’,
I would have paid her kiss for kiss
With usury thereto.’

O flourish high, with leafy towers,
And overlook the lea,
Pursue thy loves among the bowers,
But leave thou mine to me.

O flourish, hidden deep in fern,
Old oak, I love thee well;
A thousand thanks for what I learn
And what remains to tell.

‘’Tis little more: the day was warm;
At last, tired out with play,
She sank her head upon her arm,
And at my feet she lay.

‘Her eyelids dropp’d their silken eaves.
I breathed upon her eyes
Thro’ all the summer of my leaves
A welcome mix’d with sighs.

‘I took the swarming sound of life—
The music from the town—
The murmurs of the drum and fife
And lull’d them in my own.

‘Sometimes I let a sunbeam slip,
To light her shaded eye;
A second flutter’d round her lip
Like a golden butterfly;

‘A third would glimmer on her neck
To make the necklace shine;
Another slid, a sunny fleck,
From head to ancle fine,

‘Then close and dark my arms I spread,
And shadow’d all her rest—
Dropt dews upon her golden head,
An acorn in her breast.

‘But in a pet she started up,
And pluck’d it out, and drew
My little oakling from the cup,
And flung him in the dew.

‘And yet it was a graceful gift—
I felt a pang within
As when I see the woodman lift
His axe to slay my kin.

‘I shook him down because he was
The finest on the tree.
He lies beside thee on the grass.
O kiss him once for me.

‘O kiss him twice and thrice for me,
That have no lips to kiss,
For never yet was oak on lea
Shall grow so fair as this.’

Step deeper yet in herb and fern,
Look further thro’ the chace,
Spread upward till thy boughs discern
The front of Sumner-place.

This fruit of thine by Love is blest,
That but a moment lay
Where fairer fruit of Love may rest
Some happy future day.

I kiss it twice, I kiss it thrice,
The warmth it thence shall win
To riper life may magnetise
The baby-oak within.

But thou, while kingdoms overset,
Or lapse from hand to hand,
Thy leaf shall never fail, nor yet
Thine acorn in the land.

May never saw dismember thee,
Nor wielded axe disjoint,
That art the fairest-spoken tree
From here to Lizard-point.

O rock upon thy towery top
All throats that gurgle sweet!
All starry culmination drop
Balm-dews to bathe thy feet!

All grass of silky feather grow—
And while he sinks or swells
The full south-breeze around thee blow
The sound of minster bells.

The fat earth feed thy branchy root,
That under deeply strikes!
The northern morning o’er thee shoot
High up, in silver spikes!

Nor ever lightning char thy grain,
But, rolling as in sleep,
Low thunders bring the mellow rain,
That makes thee broad and deep!

And hear me swear a solemn oath,
That only by thy side
Will I to Olive plight my troth,
And gain her for my bride.

And when my marriage morn may fall,
She, Dryad-like, shall wear
Alternate leaf and acorn-ball
In wreath about her hair.

And I will work in prose and rhyme,
And praise thee more in both
Than bard has honour’d beech or lime,
Or that Thessalian growth,

In which the swarthy ringdove sat,
And mystic sentence spoke;
And more than England honours that,
Thy famous brother-oak,

Wherein the younger Charles abode
Till all the paths were dim,
And far below the Roundhead rode,
And humm’d a surly hymn.

The Talking Oak, Alfred Tennyson