Description

Del Cima OM, de Carvalho Teixeira AVN, Rocha CM, Wienke BR. Ostwald Ripening for Gas Bubbles

and Decompression in Diving. Undersea Hyperb Med. 2026 Third Quarter; 53(3):443-454.

Introduction: The Ostwald ripening phenomenon for gas bubbles in a liquid consists mainly in gas

transfer from smaller to larger bubbles. While the phenomenon itself is well known, the consequence of

the temporal evolution of bubbles in the bloodstream in human physiology lacks deeper investigation.

Methods: In this work, a series of direct experiments was carried out in which the Ostwald ripening for air

bubbles in a viscous fluid was reproduced. There, the time evolution of the bubbles' mean radius, number

of bubbles, and radius size distribution was measured, where the initial bubble distribution behaves like a

Tsallis (q-Weibull) distribution.

Results: The results show the usual behavior of wet foam, where smaller bubbles disappear, whereas

the larger bubbles, potentially dangerous for the diver, grow, and the number of bubbles decreases in

time. On the other hand, a long-time power-law regime was found with an exponent smaller than that

of the LSW (Lifshitz-Slyozov-Wagner) model, and the radius size distribution showed positive asymmetry

throughout the experiment.

Discussion: From the results obtained, it is presumed that such a bubble broadening effect could

contribute, even minimally, to decompression illness: decompression sickness and arterial gas embolism.

This conjecture is reinforced by the preliminary results of Ostwald broadening to RGBM (Reduced

Gradient Bubble Model) decompression schedules for a closed-circuit rebreather (CCR) dive to 420

feet of seawater (fsw) (128 meters of seawater (msw)) with a 21/79 Heliox gas mixture, where the first

decompression stops lengthening time thanks to Ostwald ripening is at the Pyle-type deep stop, a stop at

the half bottom depth, 210 fsw (64 msw).

Dedicated to the memory of Prof. B. R. Wienke (1940-2020).

Keywords: bubble broadening; coarse and graining; decompression sickness; RGBM.