Abyss incorporates RGBM
Dr. Bruce Wienke, Director of the Computation Testbed for Industry, Advanced Computing
Laboratory at Los Alamos National Laboratory, and the creator of the RGBM (Reduced
Gradient Bubble Model) has joined the Abysmal Diving team. Dr. Wienke will be assisting us
in the implementation of his latest decompression model into Abyss.
This means that Abyss will be the first and only product in the world with a fully
operational Bubble Mechanics model.
1. This will allow Abyss to more effectively handle Technical Repetitive decompression
diving!!!(not a small issue in itself!!)
2. Dives in which the following dive is deeper than the first. (a real potential problem
area).
3. This will also allow Abyss to run active tracking, in real time, of actual bubble
growth based upon his published and proprietary unpublished research.
RGBM/ABYSS Implementation
The Reduced Gradient Bubble Model (RGBM) is a dual phase (dissolved and free gas)
algorithm for diving calculations. Incorporating and coupling historical Haldaniean
dissolved gas transport with bubble excitation and growth, the RGBM extends the range of
computational applicability of traditional methods. The RGBM is correlated with diving and
exposure data on more complete physical principles. Much is new in the RGBM algorithm, and
troublesome multidiving profiles with higher incidence of DCS are a target here. Some
highlighted extensions for the ABYSS implementation of the Buhlmann basic algorithm
include:
1. Standard Buhlmainiann nonstop time limits;
2. Restricted repetitive exposures, particularly beyond 100 ft, based on reduction in
permissible bubble diffusion gradients within 2 hr time spans;
3. Restricted yo-yo and spike (multiple ascents and descents) dives based on excitation of
new bubble seeds;
4. Restricted deeper-than-previous divers based on excitation of very small bubble seeds
over 2 hr time spans:
5. Restricted multiday diving based on adaptation and regrowth of new bubble seeds;
6. Smooth coalescence of bounce and saturation limit points using 32 tissue compartments;
7. Consistent treatment of altitude diving, with proper zero point extrapolation of
limiting tensions and permissible bubble gradients (through zero as pressure approaches
zero);
8. Algorithm linked to diving data (tests), Doppler bubble, and laboratory micronuclei
experiments;
9. Overall, parameters in RGBM/ABYSS are conservative, but flexible and easy to change or
fit to new data.
What’s in store for the future?
Quoting from Dr. Bruce Wienke..."The ultimate computational algorithm, coupling
nucleation, dissolved gas uptake and elimination, bubble growth and collisional
coalescence, and critical sites, would be very, very complicated, requiring supercomputers
such as CRAYS or their massively parallel cousins CMs for three dimensional modeling.
Stochastic Monte Carlo methods and sampling techniques exist which could generate and
stabilize nuclei from the thermodynamic functions, such as Gibbs or Helmholtz free energy,
transport dissolved gas in flowing blood to appropriate sites, inflate, deflate, move, and
collide bubbles and nuclei, and then tally statistics on tensions, bubble size and number,
inflation and coalescence rate, free phase volume, and any other meaningful parameter, all
in necessary geometrics."
Such types of simulations of similarly complicated problems last for 16-32 hours at the
Los Alamos Laboratories, on lightning fast supercomputers with near Gigaflop speed
(1billion floating point operations per second).