Reduced Gradient Bubble Model (Buhlmann Tissue overlay)  in Abyss.

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also allow Abyss to run active tracking, in real time, of actual bubble growth based upon his published and proprietary unpublished research.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 Haldanian 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 Alimos Laboratories, on lightning fast supercomputers with near Gigaflop speed (1billion floating point operations per second)