TGQR 2010Q4 Report.pdf - Teragridforum.org

In 2010, Aidun and colleagues made use of TeraGrid resources at Purdue, LONI, NCSA and
TACC. The researchers have examined exceedingly complex noncolloidal suspensions, work
which lends itself to varied applications such as biological systems (blood flow), paper
manufacturing (wood fiber and coating flows), mining and petroleum industries (for waste
trailing), and home products (paint and cosmetics). For example, blood is comprised of elements
such as red blood cells and platelets suspended in plasma. Most computational modeling of blood
flow has simplified blood as pure fluid flow without the presence of actual suspended particles.
Understanding the physics of blood flow requires accurate simulation of the suspended solid
particles to capture the suspension structure and the blood elements on a microscale. This kind of
understanding could be important in, among other things, treating pathological blood clots, a
common cause of heart attacks and strokes, which strike more than 2 million Americans annually.
Clot formation and detachment also plays into such medical issues as the failure of popular
bileaflet mechanical heart valves. Aidun’s group published results from such simulations more
than once in 2010, including “Parallel Performance of a Lattice-Boltzmann/Finite Element
Cellular Blood Flow Solver on the IBM Blue Gene/P Architecture,” Computer Physics
Communications, 181:1013-1020, 2010. Their paper “Numerical Investigation of the Effects of
Channel Geometry on Platelet Activation and Blood Damage,” accepted by Annals of Biomedical
Engineering in October 2010, reports results that may help optimize the design of prosthetic
replacement heart valves. The researchers also are looking at extremely complex flows through
saturated deformable media, work that could provide insight into material properties of foams and
felts used in industrial applications and lead to improvement in the designs of these materials.
2.2.13
Fluid, Particulate, and Hydraulic Systems: Large Eddy Simulation Investigations of
Aviation Environmental Impacts (PI: Sanjiva Lele, Stanford)
One of the impacts about which the climate research community is very uncertain is the extent to
which aircraft change cloud cover. That’s why Sanjiva Lele and his team at Stanford University,
including PhD candidate Alexander Naiman, are studying the impact of commercial aviation on
global climate. The direct effect is known: that airplanes produce
contrails, which are clouds of ice particles, under certain atmospheric
conditions. But Lele and Naiman have shown there’s also an indirect
effect, where jet contrails induce cirrus cloud formation where clouds
might not have formed naturally otherwise. This is a concern, as
increased cloud cover may reduce a region’s temperature as well as
the amount of solar energy a region receives.
The portion of the research that's being conducted on Abe at NCSA is
a Large Eddy Simulation (LES) of contrails using a highly scalable
parallelized LES code that was developed at Stanford. It is a new
model of aircraft exhaust plume dilution that is used as a subgrid scale
model within a large-scale atmospheric simulation, providing
predictive equations for the evolution of individual exhaust plumes
based on parameters provided by the large-scale simulation. The
simulations start with the wake of a commercial airliner at a cruise
condition, one second after the airplane has passed. In addition to
solving the LES fluid equations, they also compute the deposition of
water vapor onto the ice particles that form a contrail, leading to
cirrus cloud formation. The outputs of their simulations include 3D
fields of all the simulation variables at certain time intervals, which
was not previously possible.
Current simulations continue for 1200 seconds (20 minutes), and the
Figure 2.13. This image shows 3D
isosurfaces of two quantities. The
opaque surfaces on the inside are
vorticity magnitude colored by
streamwise vorticity; these show the
development of the aircraft wake
vortices, which are what give contrails
interesting dynamics. The vortices are
initially parallel, then they form loops
and interact chaotically until they
dissipate. The translucent green/blue
outer surface shows the aircraft jet
exhaust scalar, which essentially
defines the outer extent of the contrail.
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