S. A. E. Miller, Ph.D.

The Chrysler Museum of Art features a new exhibit on Henri Matisse. Henri Matisse is a master of color and a leader of French artists experimenting in color. When these paintings emerged in the early 1900’s they were ridiculed by contemporary critics of the time. It did not take too long for the critics to be silenced. These works mark the beginning of Fauvism. In his work, `Open Window, Collioure,’ the Mediterranean sea is captured with characteristic bright colors. Simple objects in the paintings take on a clear presence with the effect of color overwhelming almost everything else. Often the paintings show simple pleasures of life, inner contemplation, or basic contentment. He also created paper collages that filled very large frames. Near the end of this early era of Fauvism, a following grew and the works became more formalized. An interesting quote adorns the wall,

I have always tried to hide my efforts and wished my works to have a light joyousness of springtime which never lets anyone suspect the labor it has cost me.

Perhaps that is a fitting quote for any creative profession.

I have recently published an article in honor of the late NASA Senior Theoretical Aeroacoustician Dr. Fereidoun `Feri’ Farassat.

During the first week I worked at NASA, while I was sending a fax, Dr. Farassat literally screamed from the other end of building 1208, Is this how NASA researchers spend their time?‘ I was surprised and confused at the time, but now this question remains in my mind everyday. The French impressionist painter Camille Pissarro wrote,everyday a line,’ I might write, `everyday an equation.’ Doing so honors those who have come before us at this prestigious organization and allows us to stand on their shoulders, especially so during this 100th Anniversary of NACA!

The article citation is

Miller, S. A. E., “The Scaling of Broadband Shock-Associated Noise with Increasing Temperature,” International Journal of Aeroacoustics, Vol. 14, Num. 1-2, 2015, pp. 305-326. DOI: 10.1260/1475-472X.14.1-2.327 [Link via DOI] [PDF Preprint]

More important than the technical contribution of the article are the lessons we learned from the person the article honors. The article contains a personal introduction,

It is a privilege to contribute an article to this special edition in honor of Dr. Fereidoun ‘Feri’ Farassat. The present article involves the use of an acoustic analogy and a Green’s function for its solution. Dr. Farassat’s career was heavily involved with both of these fundamental methods in aeroacoustics since his Ph.D. [1] work at Cornell (under advisement of Professor William R. Sears) based on the work of J. E. Ffowcs Williams and D. L. Hawkings [2]. His Ph.D. work laid the foundation for the rest of his career at NASA Langley Research Center (LaRC) within the Aeroacoustics Branch. Dr. Farassat’s developments such as Formulation 1 (Farassat [3]), Formulation 1A (Farassat and Succi [4]), the use of generalized functions (Farassat and Myers [5]), and countless others, were extremely important for the field. Some of these contributions are available on the NASA Technical Reports Server, where Dr. Farassat has over 130 publications available to the public on a wide range of topics.

Dr. Farassat, during his mid- to late-career, was undoubtedly the theoretical backbone of the Aeroacoustics Branch at NASA Langley. He had influenced the technical direction of many researchers within both the branch and NASA as a whole, and had a considerable influence throughout the community, all of which are still being felt today.

Dr. Farassat had a long history of imparting his knowledge to new researchers at NASA Langley. Some of my first and most memorable interactions with Dr. Farassat had started with these teachings. I enjoyed many technical discussions in his office and his guidance changed my technical view-point, especially relating to the acoustic analogy. These discussions saved me large amounts of time and helped me avoid many possible technical failures. He also was not afraid to offer advice, technical or personal, and was genuinely interested in the well-being of everyone he interacted with. He was an unwavering advocate within NASA for the importance of research and was extremely supportive of junior researchers.
I am proud to call Dr. Farassat my colleague and friend. Thank you Feri for the time we had together.

Abstract

A physical explanation for the saturation of broadband shock-associated noise (BBSAN) intensity with increasing jet stagnation temperature has eluded investigators. An explanation is proposed for this phenomenon with the use of an acoustic analogy. To isolate the relevant physics, the scaling of BBSAN peak intensity level at the sideline observer location is examined. The equivalent source within the framework of an acoustic analogy for BBSAN is based on local field quantities at shock wave – shear layer interactions. Propagation of sound through the jet shear layer is predicted with an adjoint vector Green’s function solver of the linearized Euler equations. The combination of the equivalent source and adjoint vector Green’s function allows for correct predictions of the saturation of BBSAN with increasing stagnation pressure and stagnation temperature. The sources and vector Green’s function have arguments involving the steady Reynolds-Averaged Navier-Stokes solution of the jet. It is proposed that saturation of BBSAN with increasing jet temperature occurs due to a balance between the amplification of the sound propagation through the shear layer and the source term scaling.

Acknowledgements

The author benefited greatly from discussions with Boeing/A. D. Welliver Professor Philip J. Morris of the Pennsylvania State University. The availability of experimental data from Professor Dennis K. McLaughlin of the Pennsylvania State University, Dr. James Bridges of NASA Glenn Research Center at Lewis Field, and Dr. Viswanathan of the Boeing Company made this work possible. The author is grateful for continuous support from The National Aeronautics and Space Administration Fundamental Aeronautics Program High Speed Project.

Some References

[1] Farassat, F., “The Sound from Rigid Bodies in Arbitrary Motion,” Cornell University Ph.D. Dissertation, January 1973.
[2] Ffowcs Williams, J. E. and Hawkings, D. L., “Sound Generation by Turbulence and Surfaces in Arbitrary Motion,” Phil. Trans. R. Soc. Lond. A, Vol. 264, No. 1151, 1969, pp. 321–342. doi:10.1098/rsta.1969.0031.
[3] Farassat, F., “Linear Acoustic Formulas for Calculation of Rotating Blade Noise,” AIAA Journal, Vol. 19, No. 9, 1981, pp. 1122-1130. doi:10.2514/3.60051.
[4] Farassat, F. and Succi, G. P., “A Review of Propeller Discrete Frequency Noise Prediction Technology with Emphasis on Two Current Methods for Time Domain Calculations,” Journal of Sound and Vibration, Vol. 71, No. 3, 1980, pp. 399–419. doi:10.1016/0022–460X(80)90422-8.
[5] Farassat, F. and Myers, M. K., “Multidimensional Generalized Functions in Aeroacoustics and Fluid Mechanics-Part 1: Basic Concepts and Operations,” International Journal of Aeroacoustics, Vol. 10, No. 2–3, June 2011, pp. 161–200. doi:10.1260/1475–472X.10.2-3.161.

One hundred years ago, March 3rd 2015, the US Congress created the National Advisory Committee for Aeronautics, the predecessor organisation of NASA. Every allied aircraft has been tested in some form or another at NASA Langley. NASA has created a few websites to celebrate,

NACA 100th Celebration and more NASA Langley specific.

It is certainly an exciting time to be a part of the organization. Over the next month there will be multiple events at NASA and within the community to celebrate!

I should also like to mention how fitting it is, that I had the opportunity to work today (and yesterday and tomorrow) at NASA Langley (site of the original NASA/NACA center), and examined one of the most difficult problems in modern physics – turbulence. That is really an honor and quite amazing! Certainly a life worth living.

While browsing the Internet I found an interesting website on abstract mathematics by Professor Charles Wells. The site is organized into subsections like chapters in a book. I’m especially interested in the use of different fonts, sizes, and colors to illustrate important points. Perhaps the important points are emphasized because of the experience of the author as a teacher. The presentation is such that most people can understand it if they have some background in the field. It is fun to review the site and remind oneself of the notation and key base concepts in abstract mathematics. It is very refreshing relative to the traditional mathematics education for engineers and scientists (that I was a part of for the most part). I wish more professional scientists, engineers, and mathematicians (read researchers) maintained personal websites or offered basic notes online. It is a service to society.

I had the pleasure of watching the opera Salome in Norfolk Virginia by the Virginia Opera. My seat was in the front row and off-set a few stage right from the center. Salome is an opera (drama) in one act after the poem of Oscar Wilde, music by Richard Strauss, first performed in 1905. As always Wikipedia has a nice article on the opera. A few of my favorite lines:

Ah ! I have kissed thy mouth, Jokanaan, I have kissed thy mouth. There was a bitter taste on thy lips. Was it the taste of blood ? . . . But perchance it is the taste of love. They say that love hath a bitter taste. . . . But what of that ? what of that ? I have kissed thy mouth, Jokanaan, I have kissed thy mouth. ~Salome

and the repetitive interactions of Salome and Jokanaan. Here she compliments, he rejects, and she changes her tune, but only in so far as to openly mock him.

Salome

Jokanaan, I am amorous of thy body ! Thy body is white like the lilies of a field that the mower hath never mowed. Thy body is white like the snows that lie on the mountains, like the snows that lie on the mountains of Judaea, and come down into the valleys. The roses in the garden of the Queen of Arabia are not so white as thy body. Neither the roses in the garden of the Queen of Arabia, nor the feet of the dawn when they light on the leaves, nor the breast of the moon when she lies on the breast of the sea. . . . There is nothing in the world so white as thy body. Let me touch thy body.

Jokanaan

Back ! daughter of Babylon ! By woman came evil into the world. Speak not to me. I will not listen to thee. I listen but to the voice of the Lord God.

SALOME

Thy body is hideous. It is like the body of a leper. It is like a plastered wall where vipers have crawled; like a plastered wall where the scorpions have made their nest. It is like a whitened sepulchre full of loathsome things. It is horrible, thy body is horrible. It is of thy hair that I am enamoured, Jokanaan. Thy hair is like clusters of grapes, like the clusters of black grapes that hang from the vine-trees of Edom in the land of the Edomites. Thy hair is like the cedars of Lebanon, like the great cedars of Lebanon that give their shade to the lions and to the robbers who would hide themselves by day. The long black nights, the nights when the moon.

Costumes were relatively contemporary. Music, acting, singing, and especially set were very good. The set was interesting in that the floor, ceiling, and walls of a burnt out palace (seemingly reminding me of a worn torn contemporary Iraq) had a focal point that converged at an almost impossible close point. This gave the effect that one would be watching the opera through a wide angle lens!

This months issue of Notices of the American Mathematical Society (Vol. 62, No. 2, Feb. 2015 pp. 152 – 160) contains an interview with Professor Yakov Sinai. The interview occurred because he won an award called the Abel prize. The interview contains a large number references to A. N. Kolmogorov! Here are a few interesting quotes,

Regarding having Kolmogorov as an adviser,

Kolmogorov had many students, and I became one of them. His students had complete freedom to work on any problem. Kolmogorov loved to discuss their results. There were several cases when Kolmogorov wrote their papers in order to teach them how to write mathematical texts.

It seems that Kolmogorov did more than most to protect his students,

The other case arose with my entrance examination to graduate school. This exam was about the history of the Communist Party; I was very bad in this topic and failed the exam (I don’t want to discuss the details). But P. S. Alexandrov, who was head of the mathematical department at Moscow State University, together with Kolmogorov, visited the head of the Chair of the History of the Party and asked her to allow me to have another attempt.

Perhaps the most important excerpt might be,

At a certain time, Kolmogorov decided that the Soviet Union did not have enough applied statistics. He worked on theoretical statistics and found many beautiful and deep results, but he was not satisfied with the fact that the theorems in applied statistics were not used for practical purposes. (…) He wanted us to work on this problem and invited a very good geophysicist, Yevgeny Fyodorov, who was one of the main experts in this field. We were sitting there; Kolmogorov and Fyodorov were present. Kolmogorov said, “Look at these people; they prefer to write a paper for Doklady instead of doing something useful” (Doklady was the leading Russian journal). In our joint paper (by M. Arató, A. Kolmogorov, and me) written on this occasion, practically everything was done and written by Kolmogorov.

One might take away from this that we should focus on producing quality research, instead of focusing on placing articles in high level journals. This might be lost on many people today, especially with the publish or perish attitude so prevalent in academic circles. In the end creating high quality works, even just one over a lifetime, is more valuable than having countless articles in any publication. The point after all is to discover or explain something that has never been thought of before.

Mr. Marcolini, the branch head who hired me in at NASA, recently retired. I had the opportunity to attend his retirement party a few days ago. Highlights were many gifts, funny stories, and an amazing NASA cake! I certainly wish him a very happy retirement. I’ll miss his advice and conversation at NASA.

I am very excited about the new year and what it might bring. I recall the words of a professor and friend who wrote, `don’t predict your future – create it.’ Wishing all my colleagues, friends, and family a happy future full of making their dreams become reality! I hope that I have some big changes in store for 2015. The next major event for me is the AIAA Aerosciences conference (now called SciTech) in Orlando, FL. I will be presenting a paper and seeing many friends and colleagues. Hopefully I will make a few new friends along the way! Happy New Year.

On Christmas day I enjoyed traveling to nearby Richmond to check out the `Virginia Fine Arts Museum.’ Perhaps a bit presumptuous with its name, they showed a few select works worth seeing. I recommend visiting the museum only if you have extra free time while in the city. They do have an impressive collection of Japanese wood block prints and silver. Disappointingly, they have almost a complete lack of British (unless you like hunting sports) work and the French galleries were closed. Admission is free and parking is five dollars. Here are some photos I took.

I’m so impressed by the art of Saya Woolfalk (personal homepage link). She recently gave a talk in Norfolk that coincides with her new exhibition. The work involves the Empathics, whom are a possible future race. They seem to be a combination between plant and human biology. Each show building on the last has led to their creation of a corporation called ChimaTek, that markets their technology. Here are two of my own personal photos.