test: add LNGship unit tests (#878)

src/test/java/neqsim/fluidMechanics/flowSystem/twoPhaseFlowSystem/shipSystem/LNGshipTest.java

@@ -0,0 +1,59 @@
+package neqsim.fluidMechanics.flowSystem.twoPhaseFlowSystem.shipSystem;
+
+import neqsim.thermo.system.SystemInterface;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class LNGshipTest {
+
+    LNGship testShip;
+    SystemInterface testSystem;
+    @BeforeEach
+    void setUp() {
+        testSystem = new neqsim.thermo.system.SystemSrkEos(100, 1.0);
+        testSystem.addComponent("methane", 0.9);
+        testSystem.addComponent("nitrogen", 0.1);
+        testSystem.init(0);
+
+        testShip = new LNGship(testSystem, 1_000_000, 0.01);
+    }
+
+    @Test
+    void createSystem() {
+        assertEquals(0.7, testShip.getLiquidDensity());
+        assertEquals(0.0, testShip.dailyBoilOffVolume);
+        assertEquals(0.0, testShip.initialNumberOffMoles);
+        testShip.createSystem();
+        assertEquals(474.3293447569919, testShip.getLiquidDensity());
+        assertEquals(10_000.0, testShip.dailyBoilOffVolume);
+        assertEquals(2.7513223265419292E10, testShip.initialNumberOffMoles);
+
+    }
+
+    @Test
+    public void testSolveSteadyState() {
+        assertEquals(-173.15, testShip.getThermoSystem().getTemperature("C"), 1e-2);
+        testShip.createSystem();
+        testShip.solveSteadyState(1, null);
+        assertEquals(-176.43, testShip.getThermoSystem().getTemperature("C"), 1e-2);
+        assertEquals(testSystem.getPhase("oil").getComponent("nitrogen").getx(), testShip.getThermoSystem().getPhase("oil").getComponent("nitrogen").getx(), 1e-4);
+        assertEquals(testSystem.getPhase("oil").getComponent("methane").getx(), testShip.getThermoSystem().getPhase("oil").getComponent("methane").getx(), 1e-4);
+    }
+
+    @Test
+    void solveTransient() {
+        assertNull(testShip.volume);
+        assertEquals(0.0, testShip.endVolume);
+        assertEquals(1_000_000, testShip.totalTankVolume); // Initial cargo volume
+
+        testShip.createSystem();
+        testShip.solveSteadyState(0, null);
+        testShip.solveTransient(0, null);
+
+
+        assertEquals(testShip.numberOffTimeSteps, testShip.tankTemperature.length); // Check that the results have correct length
+        assertEquals(600_000.0, testShip.endVolume);
+    }
+}