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Use barrier functions for PDA & emitters

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Uses continuous barrier functions to constrain PDA demands and emitter flows to allowable values (see J. Hydroinformatics, 24:697, 2022).
This commit is contained in:
Lew Rossman
2023-03-29 10:35:14 -04:00
parent ffe272462f
commit 9c79a65171
1 changed files with 45 additions and 29 deletions
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72
src/hydcoeffs.c
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@@ -7,7 +7,7 @@
Authors: see AUTHORS
Copyright: see AUTHORS
License: see LICENSE
Last Updated: 02/05/2023
Last Updated: 03/29/2023
******************************************************************************
*/
@@ -66,6 +66,41 @@ static void psvcoeff(Project *pr, int k, int n1, int n2);
static void fcvcoeff(Project *pr, int k, int n1, int n2);
void addlowerbarrier(double dq, double* hloss, double* hgrad)
/*
**--------------------------------------------------------------------
** Input: dq = difference between current flow and lower flow limit
** Output: hloss = updated head loss value
** hgrad = updated head loss gradient value
** Purpose: adds a head loss barrier to prevent flow from falling
** below a given lower limit.
**--------------------------------------------------------------------
*/
{
double a = 1.e9 * dq;
double b = sqrt(a*a + 1.e-6);
*hloss += (a - b) / 2.;
*hgrad += (1.e9 / 2.) * ( 1.0 - a / b);
}
void addupperbarrier(double dq, double* hloss, double* hgrad)
/*
**--------------------------------------------------------------------
** Input: dq = difference between current flow and upper flow limit
** Output: hloss = updated head loss value
** hgrad = updated head loss gradient value
** Purpose: adds a head loss barrier to prevent flow from exceeding
** a given upper limit.
**--------------------------------------------------------------------
*/
{
double a = 1.e9 * dq;
double b = sqrt(a*a + 1.e-6);
*hloss += (a + b) / 2.;
*hgrad += (1.e9 / 2.) * ( 1.0 + a / b);
}
void resistcoeff(Project *pr, int k)
/*
**--------------------------------------------------------------------
@@ -497,10 +532,9 @@ void emitterheadloss(Project *pr, int i, double *hloss, double *hgrad)
else *hloss = (*hgrad) * q / hyd->Qexp;
// Prevent negative flow if backflow not allowed
if (hyd->EmitBackFlag == 0 && q <= 0.0)
if (hyd->EmitBackFlag == 0)
{
*hgrad += CBIG;
*hloss += CBIG * q;
addlowerbarrier(q, hloss, hgrad);
}
}
@@ -574,32 +608,14 @@ void demandheadloss(Project *pr, int i, double dp, double n,
double dfull = hyd->NodeDemand[i];
double r = d / dfull;
// Use lower barrier function for negative demand
if (r <= 0)
{
*hgrad = CBIG;
*hloss = CBIG * d;
}
// Use power head loss function for demand less than full
else if (r <= 1.0)
{
// Evaluate inverted demand function
r = fabs(d) / dfull;
*hgrad = n * dp * pow(r, n - 1.0) / dfull;
// ... use linear function for very small gradient
if (*hgrad < hyd->RQtol)
{
*hgrad = hyd->RQtol / n;
*hloss = (*hgrad) * d;
}
else *hloss = (*hgrad) * d / n;
}
*hloss = (*hgrad) * d / n;
// Use upper barrier function for demand above full value
else
{
*hgrad = CBIG;
*hloss = dp + CBIG * (d - dfull);
}
// Add barrier functions
addlowerbarrier(d, hloss, hgrad);
addupperbarrier(d-dfull, hloss, hgrad);
}