Page 347 - Handbook Of Multiphase Flow Assurance

346 10. Research methods in flow assurance

Pi=3.14159265
nrdels=0.5D0/rdel
origns=k/2
rdelsi=rdel/sigma
2 format(2F12.6)
do 700 j=1,nrdels
radius=rdelsi*dfloat(j)
volshl=4.D0*PI*(RADIUS**3−(RADIUS−RDELSI)**3)/3.D0
GR=rdf(j)/(density*origns*volshl*(l−le+1))
write(2,2)radius*(xbox+ybox+zbox)/3.D0/side,gr
700 continue
close(1)
close(2)
end

Program for h bonded rings count in water
program ringcode; {written for AIX 3.2.3 Pascal}

{General description
This program is used to count the distribution of n–membered
ring-like paths in the network of H bonds between water molecules.
Program expects the input as the list of pairs of numbers of H bonded
oxygens as nhb array[1..n,1..2] where 1..n is the total number of
H bonds and 1..2 means that 2 water molecules represented by oxygen
atoms are connected by one H bond. The list of H bonds must be sorted
in an increasing order (for example see test array nhb2).
Output of the program is the number of unique non short circuited
closed paths. This distribution is stored in array rdist. Numbers
should be divided by 2 because each path is counted clockwise and
counterclockwise. List of atoms present in every such ring–path is
in the array ring.

Method of work

Briefly: find and test. Program searches all the possible paths
from a given point which will return to start in no more that nmax
steps. Then the ring–path is checked for short circuiting bonds.
A short circuit is defined here as a path between two points of a
ring–path, shorter or equal than the shorter distance in a ring-path
between these two points. If short–circuit is of the same length as
the shorter path in the ring, then ring–path is considered to be
short–circuited only if the number of atom in position 2 of short
circuit is greater than that of atom in position 2 in ring. Or if