Flow Resolution
News in 2023-2024 from Prof. Poggie's research group.
Recent Reading
W. van Saarloos, V. Vitelli, and Z. Zeravcic, Soft Matter: Concepts, Phenomena, and Applications, Princeton University Press, Princeton NJ, 2024. ISBN 9780691251691
Soft matter is field that focuses on liquids and solids with complicated properties. The field encompasses colloids, polymers, foams, gels, granular materials, liquid crystals, and various biological materials. In contrast to a relatively simple substance like water, the materials of interest in soft matter research typically have significant structure on a scale between that of atoms and that of the macroscopic world. They are materials with microstructure.
Soft Matter is an ambitious textbook that aims to give an overview at an introductory level of this broad field. The authors are physicists, and as a result, the textbook has a distinctive outlook. The focus is more on mathematically and physically interesting aspects of the subject matter than on applications.
The text is beautifully illustrated and attractively typset (by the authors). There are many appealing color illustrations. The layout of the book is similar to the Tufte-book LaTeX class, with wide margins for figures and side notes. At nearly 600 pages, it is a substantial book. The writing style is relatively informal.
In an effort to make the book more accessible to beginners in the field, the authors devote the first section to an overview of fluid mechanics, elasticity, Brownian motion, with an emphasis on the application of these fields to soft matter science. These chapters should be fairly accessible to a student with at least some prior background in these areas, but a class in each of the subjects would be valuable preparation for this course. Beginning students may find the notation challenging: the authors use several notations for derivatives, and they mix tensor index notation with vector (Gibbs) notation.
The next section of the book covers soft matter phases. There is a chapter each on colloids, polymers, and liquid crystals, along with a chapter on interfaces. The third section of the book treats advanced topics, including pattern formation and active matter. The text concludes with perspectives on the future development of the field of soft matter.
There is too much material for a short summary. Readers coming from a background in Newtonian fluid mechanics will find broader horizons in the director field model of liquid crystals and the odd elasticity and odd viscosity (non-symmetric stress tensor) in active matter models.
This is a valuable textbook for anyone interested in the field of soft matter. Because of its ambition and scope, there is much material for the student to digest.
Cylinder / Skewed Flare
Purdue MS student Ben Derks recently completed a a computational campaign to match a series of experiments at Mach 2.85 carried out in the 1980s at NASA Ames Research Center. The test articles were a set of cone / skewed flare configurations designed to produce highly three-dimensional shock-wave / boundary-layer interactions in the absence of end-wall effects.
The video below shows the instantaneous skin friction magnitude for detached eddy simulations for a flare inclination angle of 23 deg. A high degree of large-scale separation unsteadiness is evident in these flows.
More details are available here.
CI-PIVOT
Purdue University has an open position for a Senior Computational Scientist to advise researchers on high-performance computing and to help research teams make effective and creative use of modern computational hardware. https://bit.ly/49HF8FA The position is associated with the CI-PIVOT project.
Transverse Jet at Mach 6
The movie above shows the wall pressure field predicted by a detached-eddy simulation of a transverse jet on a 7 degree half-angle cone. The view is approximately in the downstream direction. The calculations were carried out by PhD student Matthew Dean using the DoD CREATE Kestrel KCFD code. The freestream conditions correspond to those of Purdue’s Mach 6 quiet-flow hypersonic wind tunnel, the BAM6QT. In the computation, the jet issues from a 1 mm diameter hole in the cone, at a stagnation pressure of 689 kPa. Significant large-scale unsteadiness is observed, which is the subject of ongoing computational and experimental research.
About
Prof. Poggie's research interests have encompassed the experimental, computational, and theoretical aspects of fluid dynamics and plasma physics. Current work in our research group focuses on high Mach number flow, laminar-turbulent transition, large-scale separation unsteadiness, and electrical discharges for flow control.