The challenge is to develop a realistic three-dimensional model of the heart for improved design of prosthetic heart valves, modeling of cardiac diseases, and understanding the functional anatomy of the heart. PetaFLOPS are needed to allow current promising models to be scaled to realistic levels of detail.
The present level of development successfully models some portions of
the fluid dynamics of a heartbeat. It models the heart as geodesic
fiber paths on surfaces in three dimensions, based on painstaking anatomical
dissection of mammalian hearts. Fiber forces are transmitted to the
blood by a special weighting function. Blood is represented currently
by three-dimensional lattice of points on
which fluid dynamics are calculated using versions of the Navier-Stokes
equations. The problem scales in memory as slightly less than the grid
size cubed, and in computational complexity as more than
.
Present requirements are a CRAY C90 cpu-week and 50 megawords of
memory for a single beat. Realistic improvements would require a
PetaFLOPS computer, and could be utilized immediately to refine the many
parameters, to achieve steady-state dynamics, and to introduce new
features such as electrical activity. Methods developed for this work
are applicable to problems of sperm motility, platelet aggregation, and
other problems with flexible boundaries, such as blood vessels of the
lung and heart.
Problem match to three categories of PetaFLOPS computer:
Class I machines could be utilized immediately. Very large shared memory, vectorizable, multiprocessor codes are in use. The ratio of megawords to MegaFLOPS is less than one and a high fraction of theoretical peak speed is attained.
Class II machines are likely to be useful with modification of the codes currently being developed on clustered microprocessor machines.
Class III machines are likely to be applicable as well, since they appear to be successful for other fluid dynamics codes.