FluidSystemTest Icon

`FluidSystemTest`

Models a test fluid system where a step-defined pressure source drives flow through a pipe into a fixed volume.

This FluidSystemTest component models the dynamic behavior of a fluid flowing from a pressure source through a pipe into a fixed volume. The pressure at the source is defined by a step input signal signal.y. The fluid is characterized by the medium properties, which are isothermal and compressible. The tube component accounts for frictional losses and optionally fluid inertia, with its geometry defined by tube_area and length. The vol component represents a terminal volume where fluid accumulates or is discharged.

Usage

FluidSystemTest(tube_area=0.01, add_inertia=true, tube_perimeter=2 * sqrt(tube_area * pi))

Parameters:

Name	Description	Units	Default value
`tube_area`	Cross-sectional area of the tube.	m2	0.01
`add_inertia`	Boolean flag to include fluid inertia in the tube model.	–	true

Behavior

\[ \begin{equation} \left[ \begin{array}{c} \mathtt{signal.y}\left( t \right) = \mathtt{src.p}\left( t \right) \\ \mathrm{connect}\left( src_{+}port, tube_{+}port_{a} \right) \\ \mathrm{connect}\left( tube_{+}port_{b}, vol_{+}port \right) \\ \mathtt{signal.y}\left( t \right) = ifelse\left( t \geq \mathtt{signal.start\_time}, \mathtt{signal.height} + \mathtt{signal.offset}, \mathtt{signal.offset} \right) \\ \mathtt{src.port.p}\left( t \right) = \mathtt{src.p}\left( t \right) \\ \mathtt{vol.rho}\left( t \right) = density\left( \mathtt{vol.port\_\_medium}, \mathtt{vol.p}\left( t \right) \right) \\ \mathtt{vol.m}\left( t \right) = \mathtt{vol.vol} \mathtt{vol.rho}\left( t \right) \\ \mathtt{vol.port.m\_flow}\left( t \right) = \frac{\mathrm{d} \mathtt{vol.m}\left( t \right)}{\mathrm{d}t} \\ \mathtt{vol.port.p}\left( t \right) = \mathtt{vol.p}\left( t \right) \\ \mathtt{tube.port\_a.m\_flow}\left( t \right) + \mathtt{tube.port\_b.m\_flow}\left( t \right) = 0 \\ \mathtt{tube.{\Delta}p}\left( t \right) = \mathtt{tube.port\_a.p}\left( t \right) - \mathtt{tube.port\_b.p}\left( t \right) \\ \mathtt{tube.rho}\left( t \right) = density\left( \mathtt{tube.port\_a\_\_medium}, \mathtt{tube.port\_a.p}\left( t \right) \right) \\ \mathtt{tube.mu}\left( t \right) = viscosity\left( \mathtt{tube.port\_a\_\_medium} \right) \\ \mathtt{tube.velocity}\left( t \right) = \frac{\mathtt{tube.m\_flow}\left( t \right)}{\mathtt{tube.area} \mathtt{tube.rho}\left( t \right)} \\ \mathtt{tube.ff}\left( t \right) = friction\_factor\left( \mathtt{tube.m\_flow}\left( t \right), \mathtt{tube.area}, \mathtt{tube.d\_h}, \mathtt{tube.mu}\left( t \right), \mathtt{tube.shape\_factor} \right) \\ \mathtt{tube.sheer}\left( t \right) = \frac{0.5 \mathtt{tube.head\_factor} \mathtt{tube.length} reg\_pow\left( \mathtt{tube.velocity}\left( t \right), 2 \right) \mathtt{tube.ff}\left( t \right) \mathtt{tube.rho}\left( t \right)}{\mathtt{tube.d\_h}} \\ \mathtt{tube.{\Delta}p}\left( t \right) = ifelse\left( \mathtt{tube.add\_inertia}, \frac{\mathtt{tube.length} \frac{\mathrm{d} \mathtt{tube.m\_flow}\left( t \right)}{\mathrm{d}t}}{\mathtt{tube.area}} + \mathtt{tube.sheer}\left( t \right), \mathtt{tube.sheer}\left( t \right) \right) \\ \mathtt{tube.m\_flow}\left( t \right) = \mathtt{tube.port\_a.m\_flow}\left( t \right) \\ \end{array} \right] \end{equation} \]

Source

# Models a test fluid system where a step-defined pressure source drives flow through a pipe into a fixed volume.
#
# This `FluidSystemTest` component models the dynamic behavior of a fluid flowing from a pressure source
# through a pipe into a fixed volume. The pressure at the source is defined by a step input signal `signal.y`.
# The fluid is characterized by the `medium` properties, which are isothermal and compressible.
# The `tube` component accounts for frictional losses and optionally fluid inertia, with its geometry
# defined by `tube_area` and `length`. The `vol` component represents a terminal volume where fluid
# accumulates or is discharged.
test component FluidSystemTest
  # Step input signal dictating the boundary pressure.
  signal = BlockComponents.Step(height = 1e6, start_time = 0.5)
  # Boundary pressure source.
  src = BoundaryPressure()
  # Fixed volume reservoir.
  vol = FixedVolume(vol = 10.0, p0 = 0.0)
  # Fluid conduit (pipe) with friction and optional inertia.
  tube = TubeBase(area = tube_area, head_factor = 1, length = 50, shape_factor = 64, add_inertia = add_inertia, perimeter = 2 * sqrt(tube_area * pi), m_flow0 = 0)
  # Cross-sectional area of the tube.
  parameter tube_area::Area = 0.01
  # Boolean flag to include fluid inertia in the tube model.
  parameter add_inertia::Boolean = true
  # Wetted perimeter of the tube, calculated from tube_area assuming a circular cross-section.
  final parameter tube_perimeter::Length = 2 * sqrt(tube_area * pi)
  # Path defining the properties of the working fluid (isothermal, compressible).
  path medium::AbstractMedium = IsothermalCompressible(bulk_modulus = 1e9, let_gas = false)
relations
  connect(signal.y, src.p)
  connect(src.port, tube.port_a)
  connect(tube.port_b, vol.port)
  continuity(medium, vol.port.medium)
metadata {
  "Dyad": {
    "tests": {
      "case1": {
        "stop": 2,
        "atol": {"vol.rho": 0.001, "vol.port.p": 1, "tube.m_flow": 0.001},
        "expect": {"signals": ["vol.rho", "vol.port.p", "tube.m_flow"]}
      }
    }
  }
}
end

Flattened Source

# Models a test fluid system where a step-defined pressure source drives flow through a pipe into a fixed volume.
#
# This `FluidSystemTest` component models the dynamic behavior of a fluid flowing from a pressure source
# through a pipe into a fixed volume. The pressure at the source is defined by a step input signal `signal.y`.
# The fluid is characterized by the `medium` properties, which are isothermal and compressible.
# The `tube` component accounts for frictional losses and optionally fluid inertia, with its geometry
# defined by `tube_area` and `length`. The `vol` component represents a terminal volume where fluid
# accumulates or is discharged.
test component FluidSystemTest
  # Step input signal dictating the boundary pressure.
  signal = BlockComponents.Step(height = 1e6, start_time = 0.5)
  # Boundary pressure source.
  src = BoundaryPressure()
  # Fixed volume reservoir.
  vol = FixedVolume(vol = 10.0, p0 = 0.0)
  # Fluid conduit (pipe) with friction and optional inertia.
  tube = TubeBase(area = tube_area, head_factor = 1, length = 50, shape_factor = 64, add_inertia = add_inertia, perimeter = 2 * sqrt(tube_area * pi), m_flow0 = 0)
  # Cross-sectional area of the tube.
  parameter tube_area::Area = 0.01
  # Boolean flag to include fluid inertia in the tube model.
  parameter add_inertia::Boolean = true
  # Wetted perimeter of the tube, calculated from tube_area assuming a circular cross-section.
  final parameter tube_perimeter::Length = 2 * sqrt(tube_area * pi)
  # Path defining the properties of the working fluid (isothermal, compressible).
  path medium::AbstractMedium = IsothermalCompressible(bulk_modulus = 1e9, let_gas = false)
relations
  connect(signal.y, src.p)
  connect(src.port, tube.port_a)
  connect(tube.port_b, vol.port)
  continuity(medium, vol.port.medium)
metadata {
  "Dyad": {
    "tests": {
      "case1": {
        "stop": 2,
        "atol": {"vol.rho": 0.001, "vol.port.p": 1, "tube.m_flow": 0.001},
        "expect": {"signals": ["vol.rho", "vol.port.p", "tube.m_flow"]}
      }
    }
  }
}
end

Test Cases

Test Case `case1`

plt

plt

plt

Examples
Experiments
Analyses
Tests
- BoundaryPressure
- FixedVolume