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Decoupled pressure units from the flow unit system

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Decoupled pressure units from the flow unit system, allowing them to be set independently to support mixed-unit conventions (e.g., using LPS for flow and PSI for pressure).
This commit is contained in:
lbutler
2025-07-03 08:30:43 -04:00
parent d2145a396f
commit f8f2d74bea
5 changed files with 215 additions and 15 deletions
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2
ReleaseNotes2_3.md
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@@ -42,6 +42,8 @@ This document describes the changes and updates that have been made in version 2
- `EN_PRESS_UNITS` can now be used with `EN_getoption` and `EN_setoption` to get or set the pressure unit used in EPANET.
- Decoupled pressure units from the flow unit system, allowing them to be set independently to support mixed-unit conventions (e.g., using LPS for flow and PSI for pressure).
- The following constants can be used with EN_getnodevalue to retrieve the components of a node's total demand at a given point in time:
- `EN_FULLDEMAND` - the consumer demand requested
- `EN_DEMANDFLOW` - the consumer demand delivered

2
src/epanet.c
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@@ -1411,8 +1411,6 @@ int DLLEXPORT EN_setoption(EN_Project p, int option, double value)
case EN_PRESS_UNITS:
unit = ROUND(value);
if (unit < 0 || unit > METERS) return 205;
if (p->parser.Unitsflag == US && unit > PSI) return 0;
if (p->parser.Unitsflag == SI && unit == PSI) return 0;
p->parser.Pressflag = unit;
dfactor = Ucf[DEMAND];

22
src/input1.c
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@@ -103,7 +103,7 @@ void setdefaults(Project *pr)
pr->Warnflag = FALSE; // Warning flag is off
parser->Unitsflag = US; // US unit system
parser->Flowflag = GPM; // Flow units are gpm
parser->Pressflag = PSI; // Pressure units are psi
parser->Pressflag = UNITDEFAULT; // Pressure units set based on unit system
out->Hydflag = SCRATCH; // No external hydraulics file
rpt->Tstatflag = SERIES; // Generate time series output
@@ -269,8 +269,11 @@ void adjustdata(Project *pr)
}
// Revise pressure units depending on flow units
if (parser->Unitsflag != SI) parser->Pressflag = PSI;
else if (parser->Pressflag == PSI) parser->Pressflag = METERS;
if (parser->Pressflag == UNITDEFAULT)
{
if (parser->Unitsflag == SI) parser->Pressflag = METERS;
else parser->Pressflag = PSI;
}
// Store value of viscosity & diffusivity
ucf = 1.0;
@@ -404,8 +407,6 @@ void initunits(Project *pr)
strcpy(rpt->Field[DEMAND].Units, RptFlowUnitsTxt[parser->Flowflag]);
strcpy(rpt->Field[ELEV].Units, u_METERS);
strcpy(rpt->Field[HEAD].Units, u_METERS);
if (parser->Pressflag == METERS) strcpy(rpt->Field[PRESSURE].Units, u_METERS);
else strcpy(rpt->Field[PRESSURE].Units, u_KPA);
strcpy(rpt->Field[LENGTH].Units, u_METERS);
strcpy(rpt->Field[DIAM].Units, u_MMETERS);
strcpy(rpt->Field[FLOW].Units, RptFlowUnitsTxt[parser->Flowflag]);
@@ -423,8 +424,6 @@ void initunits(Project *pr)
if (parser->Flowflag == CMS) qcf = CMSperCFS;
hcf = MperFT;
if (parser->Pressflag == METERS) pcf = MperFT * hyd->SpGrav;
else pcf = KPAperPSI * PSIperFT * hyd->SpGrav;
wcf = KWperHP;
}
else // US units
@@ -448,10 +447,17 @@ void initunits(Project *pr)
if (parser->Flowflag == IMGD) qcf = IMGDperCFS;
if (parser->Flowflag == AFD) qcf = AFDperCFS;
hcf = 1.0;
pcf = PSIperFT * hyd->SpGrav;
wcf = 1.0;
}
if (parser->Pressflag == METERS) strcpy(rpt->Field[PRESSURE].Units, u_METERS);
else if (parser->Pressflag == KPA) strcpy(rpt->Field[PRESSURE].Units, u_KPA);
else strcpy(rpt->Field[PRESSURE].Units, u_PSI);
if (parser->Pressflag == METERS) pcf = MperFT * hyd->SpGrav;
else if (parser->Pressflag == KPA) pcf = KPAperPSI * PSIperFT * hyd->SpGrav;
else pcf = PSIperFT * hyd->SpGrav;
strcpy(rpt->Field[QUALITY].Units, "");
ccf = 1.0;
if (qual->Qualflag == CHEM)

3
src/types.h
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@@ -238,7 +238,8 @@ typedef enum {
typedef enum {
PSI, // pounds per square inch
KPA, // kiloPascals
METERS // meters
METERS, // meters
UNITDEFAULT // default based on unit system (SI or US)
} PressureUnitsType;
typedef enum {

201
tests/test_units.cpp
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@@ -74,13 +74,13 @@ BOOST_FIXTURE_TEST_CASE(test_pressure_units, FixtureInitClose)
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_PSI);
// Change to pressure from PSI to meters and check it's still PSI
// Change to pressure from PSI to meters and check it is meters
error = EN_setoption(ph, EN_PRESS_UNITS, EN_METERS);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_PSI);
BOOST_CHECK(units == EN_METERS);
// Change flow units to LPS to change to metric units and rerun simulation
error = EN_setflowunits(ph, EN_LPS);
@@ -108,12 +108,12 @@ BOOST_FIXTURE_TEST_CASE(test_pressure_units, FixtureInitClose)
BOOST_REQUIRE(error == 0);
BOOST_CHECK(abs(p - 298.76035) < 1.e-5);
// Set pressure to PSI and check that it remains in kPa
// Set pressure to PSI and check that it has changed to PSI
error = EN_setoption(ph, EN_PRESS_UNITS, EN_PSI);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_KPA);
BOOST_CHECK(units == EN_PSI);
error = EN_closeH(ph);
BOOST_REQUIRE(error == 0);
@@ -264,4 +264,197 @@ BOOST_FIXTURE_TEST_CASE(test_rule_unit_change, FixtureOpenClose)
}
BOOST_FIXTURE_TEST_CASE(test_decoupled_pressure_units, FixtureInitClose)
{
int index;
long t;
double p, units;
// Create basic network
error = EN_addnode(ph, "R1", EN_RESERVOIR, &index);
BOOST_REQUIRE(error == 0);
error = EN_setnodevalue(ph, index, EN_ELEVATION, 100);
BOOST_REQUIRE(error == 0);
error = EN_addnode(ph, "J1", EN_JUNCTION, &index);
BOOST_REQUIRE(error == 0);
error = EN_addlink(ph, "P1", EN_PIPE, "R1", "J1", &index);
BOOST_REQUIRE(error == 0);
// Test 1: Start with US flow units (GPM) and change to PSI
error = EN_setflowunits(ph, EN_GPM);
BOOST_REQUIRE(error == 0);
// Should succeed in setting PSI pressure units
error = EN_setoption(ph, EN_PRESS_UNITS, EN_PSI);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_PSI);
// Test 2: With US flow units, set pressure to meters (should now work)
error = EN_setoption(ph, EN_PRESS_UNITS, EN_METERS);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_METERS);
// Test 3: With US flow units, set pressure to kPa (should now work)
error = EN_setoption(ph, EN_PRESS_UNITS, EN_KPA);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_KPA);
// Test 4: Change to SI flow units (LPS) but keep kPa pressure
error = EN_setflowunits(ph, EN_LPS);
BOOST_REQUIRE(error == 0);
// Pressure units should remain kPa (not auto-changed to meters)
error = EN_getoption(ph, EN_PRESS_UNITS, &units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_KPA);
// Test 5: With SI flow units, set pressure to PSI (should now work)
error = EN_setoption(ph, EN_PRESS_UNITS, EN_PSI);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(units == EN_PSI);
// Test 6: Run simulation and check pressure values are correctly converted
error = EN_openH(ph);
BOOST_REQUIRE(error == 0);
error = EN_initH(ph, EN_NOSAVE);
BOOST_REQUIRE(error == 0);
error = EN_runH(ph, &t);
BOOST_REQUIRE(error == 0);
// Get pressure in PSI (should be ~43.33 PSI for 100 ft head)
error = EN_getnodevalue(ph, 1, EN_PRESSURE, &p);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(abs(p - 43.33) < 1.e-5);
// Change pressure units to meters during simulation
error = EN_setoption(ph, EN_PRESS_UNITS, EN_METERS);
BOOST_REQUIRE(error == 0);
// Pressure should now be in meters (~30.48 m for 100 ft head)
error = EN_getnodevalue(ph, 1, EN_PRESSURE, &p);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(abs(p - 30.48) < 1.e-5);
error = EN_closeH(ph);
BOOST_REQUIRE(error == 0);
}
BOOST_FIXTURE_TEST_CASE(test_automatic_pressure_unit_switching, FixtureInitClose)
{
int index;
double pressure_units;
// Create basic network
error = EN_addnode(ph, "R1", EN_RESERVOIR, &index);
BOOST_REQUIRE(error == 0);
error = EN_setnodevalue(ph, index, EN_ELEVATION, 100);
BOOST_REQUIRE(error == 0);
error = EN_addnode(ph, "J1", EN_JUNCTION, &index);
BOOST_REQUIRE(error == 0);
error = EN_addlink(ph, "P1", EN_PIPE, "R1", "J1", &index);
BOOST_REQUIRE(error == 0);
// Test 1: Start with US flow units (CFS) - should have PSI pressure units
error = EN_setflowunits(ph, EN_CFS);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_PSI);
// Test 2: Change from US flow units (CFS) to metric flow units (LPS)
// Pressure units should automatically change from PSI to METERS
error = EN_setflowunits(ph, EN_LPS);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_METERS);
// Test 3: Change from metric flow units (LPS) back to US flow units (GPM)
// Pressure units should automatically change from METERS to PSI
error = EN_setflowunits(ph, EN_GPM);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_PSI);
// Test 4: Change from US flow units (GPM) to another metric flow unit (MLD)
// Pressure units should automatically change from PSI to METERS
error = EN_setflowunits(ph, EN_MLD);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_METERS);
// Test 5: Manually set pressure units to kPa while using metric flow units
error = EN_setoption(ph, EN_PRESS_UNITS, EN_KPA);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_KPA);
// Test 6: Change from metric flow units (MLD) to US flow units (MGD)
// Pressure units should automatically change from kPa to PSI
error = EN_setflowunits(ph, EN_MGD);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_PSI);
// Test 7: Change from US flow units (MGD) to metric flow units (CMH)
// Pressure units should automatically change from PSI to METERS
error = EN_setflowunits(ph, EN_CMH);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_METERS);
// Test 8: Set pressure to kPa again with metric flow units
error = EN_setoption(ph, EN_PRESS_UNITS, EN_KPA);
BOOST_REQUIRE(error == 0);
// Test 9: Change between metric flow units (CMH to CMD)
// Pressure units should remain kPa (not changed to METERS since not switching from PSI)
error = EN_setflowunits(ph, EN_CMD);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_KPA);
// Test 10: Change from metric flow units (CMD) to US flow units (AFD)
// Pressure units should automatically change from kPa to PSI
error = EN_setflowunits(ph, EN_AFD);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_PSI);
// Test 11: Change between US flow units (AFD to IMGD)
// Pressure units should remain PSI
error = EN_setflowunits(ph, EN_IMGD);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_PSI);
// Test 12: Final test - metric flow units (CMS) should change PSI to METERS
error = EN_setflowunits(ph, EN_CMS);
BOOST_REQUIRE(error == 0);
error = EN_getoption(ph, EN_PRESS_UNITS, &pressure_units);
BOOST_REQUIRE(error == 0);
BOOST_CHECK(pressure_units == EN_METERS);
}
BOOST_AUTO_TEST_SUITE_END()