NASA Technical Reports Server (NTRS) 20150009408: Simulation Apps Bring Us Closer to Mars

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by  NASA Technical Reports Server (NTRS)

GUEST EDITORIAL
Simulation Apps Bring Us
Closer to Mars
by JIM KNOX, MARSHALL SPACE FLIGHT CENTER, NASA
My work with mathematical modeling and computer Exploration Systems
simulations began in earnest in 1987 when I signed on with program, is keeping abreast
the National Aeronautics and Space Administration, better of parallel developments in
known as NASA. At the time I was developing computer CO capture and storage.
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simulations to support the design of carbon dioxide (CO) While listening to a speaker
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removal systems for the International Space Station (ISS) life at a recent conference, I was
support system. CO is a human metabolic waste, produced struck by his conclusion: For
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at a rate of a kilogram per day per crewmember. CO must this complex technology,
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be removed from the crew cabin, as it will quickly become standard figures of merit
detrimental to crew health. The systems used to remove cannot be used to optimize
CO are typically based on sorption processes, which include the processes involved.
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complex interactions of heat transfer, mass transfer, and Rather, computer simulations
gas flow through porous media. At this time, there were no that capture the key physics
commercial options for solving a set of coupled mathematical of the process, including
models such as partial differential equations (PDEs); you coupled heat and mass Jim Knox is the functional area
manager for maturation of CO
either force-fit the physics into a thermal analysis package transfer in porous media, 2
Removal systems within NASA’s
or wrote your own code, complete with discretization, must be applied. A large
Advanced Exploration Systems
meshing, and solution algorithms. Unfortunately, coding CO number of parametric
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removal processes from scratch did not allow an appropriate simulations are required to
aerospace engineering from the
focus on the challenging yet crucial task of understanding converge on the optimal University of Colorado and an MS
and capturing the underlying physics via appropriate solution. Parametric testing in mechanical engineering from the
could also be employed, University of Alabama. Research
of course, but would be using COMSOL Multiphysics® to
“The Application Builder will provide
prohibitively expensive and simulate adsorption processes
the means to distribute the workload time-consuming, severely is part of his ongoing PhD
dissertation.
limiting the number of
to many individuals.”
options that can be explored.
Multiphysics applications have made great strides in solver
mathematical models. Configuration control was often simply robustness and speed. However, to accelerate 1D system
ignored due to tight schedules, resulting in a code that would simulations and enable multidimensional modeling of full
be quicker for a second party to rewrite than modify. CO removal systems, further improvements in robustness,
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In the early 2000s, I decided to move CO removal simulations execution rate, and memory usage are highly desirable
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to a platform with built-in meshing, solvers, and postprocessing future developments.
capabilities, and that could solve user-defined multiphysics One feature that can be applied now to increase the
PDEs. The program chosen to meet these needs was execution rate of parametric studies is the Application
COMSOL Multiphysics®. Along with freeing the engineer to focus Builder in COMSOL Multiphysics®. After verification of a CO
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on the underlying physics, a degree of configuration control removal simulation against test results, the configuration
was automatically achieved via a consistent user interface, thus can be locked down and a simulation app distributed to
allowing COMSOL users to share computer models. My team multiple users for parallel parametric studies. Examples of
has developed simulations that are already providing a valuable parametric variables include sorbent selections, fixed bed
debugging capability for the ISS CO removal system, and will size, cycle times, and flow rates. The recent development of
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provide guidance in upgrades to that system. the Application Builder is very timely, as it will seamlessly
As NASA looks to the next phase of human space travel, first facilitate this process.
to the vicinity of Mars, and then eventually to the Mars surface, In summary, early investigation of COMSOL as a platform
the need for robust and efficient systems takes a quantum for parametric studies towards maturation of spacecraft CO
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leap. Unlike on ISS, resupply is unavailable, and early return is removal systems appears very promising. The Application
impossible. Design of CO removal systems thus requires a new Builder will provide the means to distribute the workload to
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degree of optimization, including selection of adsorbents and many individuals. With this approach, informed selections
sorbent processes. from a wide range of possible options can be made towards
One facet of my current position, guiding the maturation finding the best solution of a CO removal system for the
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of spacecraft CO removal technologies for NASA’s Advanced crew traveling to, and landing on, the Red Planet. v
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