Page 322 - The Combined Finite-Discrete Element Method

NBS CONTACT DETECTION ALGORITHM IN 3D 305

.........continued from previous listing.............
/* add forces into global vector */
for(i=0;i<4;i++)
{ d1ncfx[ipc[i]]]=d1ncfx[ipc[i]]]+fc[i]*xnc;
d1ncfy[ipc[i]]=d1ncfy[ipc[i]]+fc[i]*ync;
d1ncfz[ipc[i]]=d1ncfz[ipc[i]]+fc[i]*znc;
d1ncfx[ipt[i]]]=d1ncfx[ipt[i]]]-ft[i]*xnc;
d1ncfy[ipt[i]]=d1ncfy[ipt[i]]-ft[i]*ync;
d1ncfz[ipt[i]]=d1ncfz[ipt[i]]-ft[i]*znc;
} }}}
Listing 10.20 Adding forces to the global force vector.

void TsortINT(n,nsort,nrear,i2)
/* Sorts nsort arrays - smallest...largest */
/* and rearrange nrear-nsort arrays same way */
INT n; INT nsort; INT nrear; INT **i2;
{ INT iblock,i,j,k,isort,tmp,m;
INT *il, *ilr;
INT ibig[50];
INT iend[50];
ibig[0]=0;
iend[0]=n-1;
iblock=0;
Listing 10.21 Sorting a set of one-dimensional integer arrays– local variables.

First the space boundaries are calculated using a loop over all discrete elements, as
shown in Listing 10.24. The second step is a calculation of total number of cells in the
x, y and z direction (ncelx, ncely, ncelz) (Listing 10.25).
Once the required number of cells in each direction is known, dynamic memory allo-
cation is performed and dynamic arrays are created (Listing 10.26).
A one-dimensional integer array i1cfz[ncelz] is allocated to store the first element
(head) of each of the lists containing discrete elements mapped onto the same layer of
cells (z direction).
Two one-dimensional arrays, i2cfy[0] and i2cfy[1], are allocated for storing the heads
of y-lists for layers (iz-1)and iz, respectively (where iz is the current central layer). Two
one-dimensional arrays, i2cfx[0] and i2cfx[1], are allocated to store the heads of x-lists.
Array i2cfx[0] stores the heads of all x-lists for the central row iy; array i2cfx[1] stores the
heads of all x-lists containing all the discrete elements from all y-rows that are neighbouring
rows of the central row iy according to the contact map. Arrays i1cnz, i1cny and i1cnx are
one-dimensional arrays used to store, for each discrete element, the next discrete element
that is in the same z-list, y-list or x-list, respectively. Listing 10.27 represents initialisation,
where all lists are initialised in such a way that they represent empty lists. The first loop in
the listing makes all z-lists empty lists. The second loop makes all lists of both sets of y-lists
empty. The third loop makes all lists of both sets of x-lists empty.
In Listing 10.28, all discrete elements are placed onto the corresponding z-list according
to the z-coordinates of each discrete element. This is done using the loop over all discrete