VPMechanics6

Copyright 1999-2001 Eric Maiken

PssNew and Variation of the Parameters

This notebook considers the dependence of the allowed supersaturation gradients PssNew on decompression time, dive pressure, and critical volume.

PssNew vs. decompression time tD and critical volume  λ

The set of 16  PssNew corresponding to the ZHL16 compartments are plotted below against decompression time, with fixed ΔP = 3 atm, and
λ =. The curves follow the color association to the ZHL16 compartments shown in the last plot of VPMechanics4, with red the fastest, and purple the longest half-time.
After approximately 60 min, there is little difference between the PssNew.

At the no decompression limit of a 100 ft dive, the variation of PssNew with the (scaled) critical volume  λ is shown below. tD = 0 min and ΔP = 3 atm.
The plot ranges from approximately one-half to twice the critical volume used in the Y&H paper.

The allowable PssNew decreases with longer decompression times and with smaller allowed critical volumes (ie lesser λ). For decompression times greater than approximately 30 min, the PssNew are nearly insensitive to the parameter λ, which tracks the critical volume.
The two preceding plots depict the intersection of the PssNew surfaces shown below with the tD = 0 min and λ = planes.

PssNew vs. pressure change ΔP and critical volume λ

The following plot's facing Pss/ ΔP plane is identical to the graph "Converged Supersaturation Gradients" in the VPMechanics4 notebook, which plots PssNew vs. ΔP , with fixed λ. This notebook's second graph "ZHL16 PssNew vs. λ at the NDL" corresponds to the trace left on the ΔP = 3 atm plane by the following stack of 16 surfaces.

The dispersion of PssNew vs. pressure change ΔP and decompression time tD

This surface  illustrates the range of allowable saturations  by plotting the difference between the 4 and 635 min ZHL16 compartments against the total decompression time and the change in hydrostatic pressure:
,
with λ = 218 (Ata min).

Compare the above plot's intersection with the tD = 0 min plane to the  "Converged Supersaturation Gradients" in the VPMechanics4 notebook, where the difference between the red line that tracks the 635 compartment and the purple line that tracks the 4 min compartment correspond to the following set of dispersions: