double form1Eqn(double yc, void* p)
//
// Input: yc = critical depth
// p = pointer to a TCulvert object
// Output: returns residual error
// Purpose: evaluates the error in satisfying FHWA culvert Equation Form1:
//
// h/yFull + 0.5*s = yc/yFull + yh/2/yFull + K[ac/aFull*sqrt(g*yh/yFull)]^M
//
// for a given value of critical depth yc where:
// h = inlet depth above culvert invert
// s = culvert slope
// yFull = full depth of culvert
// yh = hydraulic depth at critical depth
// ac = flow area at critical depth
// g = accel. of gravity
// K and M = coefficients
//
{
double ac, wc, yh;
TCulvert* culvert = (TCulvert *)p;
ac = xsect_getAofY(culvert->xsect, yc);
wc = xsect_getWofY(culvert->xsect, yc);
yh = ac/wc;
culvert->qc = ac * sqrt(GRAVITY * yh);
return culvert->hPlus - yc/culvert->yFull - yh/2.0/culvert->yFull -
culvert->kk * pow(culvert->qc/culvert->ad, culvert->mm);
}
double storage_getOutflow(int j, int i)
//
// Input: j = node index
// i = link index
// Output: returns flow from storage node into conduit link (cfs)
// Purpose: finds outflow from a storage node into its connecting conduit link
// ( non-conduit links have their own getInflow functions).
//
{
int k;
double a, y;
// --- link must be a conduit
if ( Link[i].type != CONDUIT ) return 0.0;
// --- find depth of water in conduit
y = Node[j].newDepth - Link[i].offset1;
// --- return 0 if conduit empty or full flow if full
if ( y <= 0.0 ) return 0.0;
if ( y >= Link[i].xsect.yFull ) return Link[i].qFull;
// --- if partially full, return normal flow
k = Link[i].subIndex;
a = xsect_getAofY(&Link[i].xsect, y);
return Conduit[k].beta * xsect_getSofA(&Link[i].xsect, a);
}
void initLinks()
//
// Input: none
// Output: none
// Purpose: sets initial upstream/downstream conditions in links.
//
// Note: initNodes() must have been called first to properly
// initialize each node's crown elevation.
//
{
int i; // link index
int j; // node index
int k; // conduit or pump index
double z; // crown elev. (ft)
// --- examine each link
for ( i = 0; i < Nobjects[LINK]; i++ )
{
// --- examine each conduit
if ( Link[i].type == CONDUIT )
{
// --- assign initial flow to both ends of conduit
k = Link[i].subIndex;
Conduit[k].q1 = Link[i].newFlow / Conduit[k].barrels;
Conduit[k].q2 = Conduit[k].q1;
Conduit[k].q1Old = Conduit[k].q1;
Conduit[k].q2Old = Conduit[k].q2;
// --- find areas based on initial flow depth
Conduit[k].a1 = xsect_getAofY(&Link[i].xsect, Link[i].newDepth);
Conduit[k].a2 = Conduit[k].a1;
// --- compute initial volume from area
Link[i].newVolume = Conduit[k].a1 * link_getLength(i) *
Conduit[k].barrels;
Link[i].oldVolume = Link[i].newVolume;
}
// --- update crown elev. of nodes at either end
j = Link[i].node1;
z = Node[j].invertElev + Link[i].offset1 + Link[i].xsect.yFull;
Node[j].crownElev = MAX(Node[j].crownElev, z);
j = Link[i].node2;
z = Node[j].invertElev + Link[i].offset2 + Link[i].xsect.yFull;
Node[j].crownElev = MAX(Node[j].crownElev, z);
}
}
void initLinks(Project* project, int routingModel)
//
// Input: none
// Output: none
// Purpose: sets initial upstream/downstream conditions in links.
//
{
int i; // link index
int k; // conduit or pump index
// --- examine each link
for ( i = 0; i < project->Nobjects[LINK]; i++ )
{
if ( routingModel == SF) project->Link[i].newFlow = 0.0;
// --- otherwise if link is a conduit
else if ( project->Link[i].type == CONDUIT )
{
// --- assign initial flow to both ends of conduit
k = project->Link[i].subIndex;
project->Conduit[k].q1 = project->Link[i].newFlow / project->Conduit[k].barrels;
project->Conduit[k].q2 = project->Conduit[k].q1;
// --- find areas based on initial flow depth
project->Conduit[k].a1 = xsect_getAofY(project, &project->Link[i].xsect, project->Link[i].newDepth);
project->Conduit[k].a2 = project->Conduit[k].a1;
// --- compute initial volume from area
{
project->Link[i].newVolume = project->Conduit[k].a1 * link_getLength(project, i) *
project->Conduit[k].barrels;
}
project->Link[i].oldVolume = project->Link[i].newVolume;
}
}
}
