def testFlowsMeasuring3D_1(self):
        vel = Kratos.Array3()
        vel[0] = 0.0
        vel[1] = 0.0
        vel[2] = 1.0
        node = self.fluid_model_part.CreateNewNode(1, 0.0, 0.0, 0.0)
        node.SetSolutionStepValue(Kratos.VELOCITY, vel)
        node = self.fluid_model_part.CreateNewNode(2, 1.0, 0.0, 0.0)
        node.SetSolutionStepValue(Kratos.VELOCITY, vel)
        node = self.fluid_model_part.CreateNewNode(3, 0.0, 1.0, 0.0)
        node.SetSolutionStepValue(Kratos.VELOCITY, vel)
        node = self.fluid_model_part.CreateNewNode(4, 1.0, 1.0, 0.0)
        node.SetSolutionStepValue(Kratos.VELOCITY, vel)
        vel[0] = 1.0
        vel[1] = 0.0
        vel[2] = 0.0
        node = self.fluid_model_part.CreateNewNode(5, 2.0, 0.0, 0.0)
        node.SetSolutionStepValue(Kratos.VELOCITY, vel)
        node = self.fluid_model_part.CreateNewNode(6, 2.0, 0.0, 1.0)
        node.SetSolutionStepValue(Kratos.VELOCITY, vel)
        node = self.fluid_model_part.CreateNewNode(7, 2.0, 1.0, 0.0)
        node.SetSolutionStepValue(Kratos.VELOCITY, vel)

        condition_name = "SurfaceCondition3D3N"
        self.fluid_model_part.CreateNewCondition(
            condition_name, 1, [1, 2, 3],
            self.fluid_model_part.GetProperties()[0])
        self.fluid_model_part.CreateNewCondition(
            condition_name, 2, [3, 2, 4],
            self.fluid_model_part.GetProperties()[0])
        self.fluid_model_part.CreateNewCondition(
            condition_name, 3, [5, 6, 7],
            self.fluid_model_part.GetProperties()[0])

        first_smp = self.fluid_model_part.CreateSubModelPart("first")
        first_smp.AddConditions([1, 2])
        second_smp = self.fluid_model_part.CreateSubModelPart("second")
        second_smp.AddConditions([3])

        flow_value_first = Fluid.FluidPostProcessUtilities().CalculateFlow(
            first_smp)
        flow_value_second = Fluid.FluidPostProcessUtilities().CalculateFlow(
            second_smp)

        self.assertAlmostEqual(flow_value_first, 1.0)
        self.assertAlmostEqual(flow_value_second, -0.5)
 def CalculateFlow(self, model_part):
     flow_value = KratosCFD.FluidPostProcessUtilities().CalculateFlow(
         model_part)
     return flow_value