Editing Appendix/Ramblings/MyDoctoralStudents (section)

===Years 1994 - 2000===
<!-- 1994 - 2000 -->
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  <td align="center">[http://www.phys.lsu.edu/~tohline/ref_ref.html Pubs.] <font color="red">(rank)</font></td>
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Our earlier CFD modeling of rapidly rotating polytropes showed that configurations that are sufficiently rapidly rotating will be subject to a dynamical bar-mode instability.  <font color="red">John E. Cazes</font> showed that the nonlinear development of this instability usually results in the formation of a dynamically ''stable,'' self-gravitating structure that appears to be a compressible analog of a Riemann ellipsoid.  Often, differential fluid flows inside the bar were supersonic and exhibited mild standing shocks near the ends of the bar, so the structure of each bar was necessarily expected to change on a secular time scale. After introducing a mechanism for slowly cooling the bar, Cazes observed that the bar became steadily more elongated and tended to develop a pair of off-axis density maxima.  This ''suggested'' &#8212; but did not convincingly show &#8212; that as star-forming clouds slowly contract, they can smoothly transition from stable bar-like structures to binary protostellar configurations.

In an effort to ascertain whether the results obtained from Woodward's earlier CFD-based examination of the stability of toroidal configurations were consistent with the results of linear stability analyses previously published by other groups, <font color="red">Saied W. Andalib</font> completed a project &#8212; in close collaboration with Christodoulou &#8212; titled, "A Survey of the Principal Modes of Nonaxisymmetric Instability in Self-Gravitating Accretion-Disk Models."  Andalib also developed a technique for constructing 2D equilibrium structures of compressible and differentially rotating ''disks'' that exhibit nonlinear distortions in the azimuthal coordinate direction.  (A very similar technique is described in the 1996 publication by [[Apps/Korycansky_Papaloizou_1996#Korycansky_and_Papaloizou_.281996.29|Korycansky &amp; Papaloizou]].)  The variety of model geometries that were obtained with this new tool helped us place in better context the range of distorted models that developed spontaneously during John Cazes' simulations.

Over this time period, we continued to receive NSF allocations of supercomputing time, but we shifted from the CTC to the [https://www.sdsc.edu San Diego Supercomputing Center (SDSC)] for two reasons:  (1) It appeared to us that it would be relatively easy for us to migrate the parallel version of our CFD code &#8212; which had been developed using MasPar Fortran &#8212; to the SDSC's Cray T3D (then T3E) because PGHPF (Portland Group's High-Performance Fortran) was a supported compiler on the Cray platforms.   (2) The SDSC's new ''Advanced Scientific Visualization Laboratory (Vislab)'' was providing access to visualization tools on its Silicon Graphics Onyx2, such as Alias|Wavefront.  At approximately the same time, a virtually identical computing environment was developed at the DoD's new [http://benchpub.powweb.com/GULFPORT03/resources/03.html Major Shared Resource Center (MSRC) in Stennis, MS]; after being introduced to the MSRC's managers by Warren N. Waggenspack Jr. (LSU, Mechanical Engineering), we also received an allocation of time on these computing resources via the [http://aspen.ucs.indiana.edu/pet/ DoD's Programming Environment &amp; Training (PET) program].

In relatively short order we figured out that the PGHPF compiler did not generate efficient executable code on the MIMD-architecture Cray T3E.  <font color="red">Patrick M. Motl</font> rewrote the CFD code using explicit message-passing instructions (MPI) and realized a significant speedup of the executable code.
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<b>[</b>[https://digitalcommons.lsu.edu/gradschool_disstheses/6982/ <math>~\odot</math>]<b>]</b><br />
<b>[</b>[https://ui.adsabs.harvard.edu/abs/2000ApJ...532.1051C/abstract 54]<b>]</b><br />
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<b>[</b>[https://digitalcommons.lsu.edu/gradschool_disstheses/6650/ <math>~\odot</math>]<b>]</b><br />
<b>[</b>[https://ui.adsabs.harvard.edu/abs/1997ApJS..108..471A/abstract 47]<b>]</b><br />
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<b>[</b>[http://www.phys.lsu.edu/faculty/tohline/SDSC/T3E.timings.html#part1 web]<b>]</b><br />
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<b>[</b>[https://digitalcommons.lsu.edu/gradschool_disstheses/6940/ <math>~\odot</math>]<b>]</b><br />
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<b>[</b>[https://digitalcommons.lsu.edu/gradschool_disstheses/6269/ <math>~\odot</math>]<b>]</b><br />
<b>[</b>[https://ui.adsabs.harvard.edu/abs/1997ApJ...490..311N/abstract 51]<b>]</b> <font color="red">(25<sup>th</sup>)</font><br />
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<b>[</b>[https://digitalcommons.lsu.edu/gradschool_disstheses/6983/ <math>~\odot</math>]<b>]</b><br />
<b>[</b>[http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.33.3594&rep=rep1&type=pdf 50]<b>]</b><br />
<b>[</b>[https://ui.adsabs.harvard.edu/abs/1999ApJ...527...86C/abstract 53]<b>]</b> <font color="red">(6<sup>th</sup>)</font><br />
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<b>[</b>[http://www.phys.lsu.edu/faculty/tohline/CiSE/CiSE2007.Vol9No6.pdf Viz]<b>]</b><br />
<b>[</b>[http://www.phys.lsu.edu/faculty/tohline/CIP/article.html HCE]<b>]</b><br />
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Building on the foundation ideas developed earlier in collaboration with Caldwell and Simonson, and, in effect, extending Christodoulou's earlier CFD simulations, <font color="red">Paul Fisher</font> used our MasPar-based CFD code to model the secular settling of ''thin'' galaxy disks toward the equatorial plane of spheroidal halos.  The observed behavior of these settling disks was unexpected, as the underlying equatorial plane of the halo did not seem to serve as a ''preferred plane.''  This discrepancy may have resulted from artificial constraints on the disk's velocity field that were unintentionally imposed at the time by our CFD algorithm.
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Using the HSCF technique, <font color="red">Kimberly C. B. New</font> (now, Scott) constructed equilibrium models of ''synchronously rotating, equal-mass binary stars'' along various physically relevant sequences:  White dwarf sequences having various total masses, and ''Newtonian'' neutron star (NS) sequences having different possible NS equations of state.  Each equilibrium sequence was composed of binaries having varying separations, allowing for detached, contact, or common-envelope structures.  She then used our MasPar-based CFD code to follow in a self-consistent manner the time-evolutionary motion of these extended fluid systems in order to determine along each equilibrium sequence which, if any, configurations were dynamically unstable toward merger.
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<font color="red">Howard S. Cohl</font> made two key contributions to the development of our Poisson solver:  (1) A parallel implementation of a data-transpose technique to facilitate, on our SIMD-architecture MasPar, fast execution of an iterative scheme to evaluate the Newtonian gravitational potential throughout the interior volume of the grid; and (2) a compact cylindrical Green's function (CCGF) expansion that much more effectively facilitates an accurate evaluation of potential values along the exterior boundary of our cylindrical-coordinate grid.  

Comment from Tohline:  &nbsp;As has been detailed in an [[Appendix/Ramblings/CCGF#Compact_Cylindrical_Green_Function_.28CCGF.29|accompanying chapter on this CCGF paper]], over my professional career this has proven to be the publication with the most citations from research groups outside of the astrophysics community.  Howard Cohl deserves full credit for the important discovery presented in this paper; I simply tagged along as his physics doctoral dissertation advisor and harshest skeptic.
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In collaboration with Monika Lee, and at three different sites &#8212; see accompanying table &#8212; <font color="red">John Cazes</font> and <font color="red">Howard Cohl</font> developed a ''heterogeneous computing environment'' (HCE) through which our two primary computational tasks (CFD simulation and visualization) were performed simultaneously on two separate computing platforms, each of which was configured to handle the assigned task in an optimum fashion. Communication between the tasks (the link) was accomplished over existing local area networks.
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  <th align="right" rowspan="2">TASK:&nbsp; &nbsp;</th>
  <th align="center">CFD Simulation</th>
  <th align="center" colspan="2">''the link''</th>
  <th align="center">Visualization</th>
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  <td align="center">Platform</td>
  <td align="center">data transfer</td>
  <td align="center">process control</td>
  <td align="center">Platform</td>
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  <td align="center">@ LSU<br />(1993)</td>
  <td align="center">MasPar MP1</td>
  <td align="center">NFS cross-mounted disks</td>
  <td align="center">unix sockets</td>
  <td align="center">Sparcstation</td>
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  <td align="center">@ SDSC &amp; @ Stennis<br />(1998)</td>
  <td align="center">Cray T3E</td>
  <td align="center">ftp</td>
  <td align="center">remote shell script</td>
  <td align="center">SGI Onyx</td>
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