The Pipe (Advanced) (IL) unit simulates flow in a pipe with rigid or flexible walls with losses due to wall friction. Optionally, the effects of dynamic compressibility, fluid inertia and pipe lift can be modelled. You can define multiple pipe segments and set the fluid pressure for each segment. By dividing the pipe into segments and selecting the Fluid inertia checkbox, it is possible to simulate water hammer in the system.
Pipe Characteristics
The Number of segments parameter allows you to specify the number of segments into which the pipe is divided. If the pipe consists of several segments, the pressure in each segment is calculated based on the inlet pressure and the effect of fluid compressibility and wall flexibility on the mass flow rate in the segment, if considered. The volume of fluid in each segment remains unchanged. For a two-segment pipe, the pressure varies linearly with the pressure determined at ports A and B. For a pipe with three or more segments, you can specify the liquid pressure in each segment as a vector or scalar in the Initial liquid pressure parameters. If Initial liquid pressure is set as a scalar, a constant pressure value will be used for all segments.
Flexible Walls
Flexible walls can be modelled for all cross-sectional geometries.
If the Flexible pipe wall checkbox is selected, uniform expansion along all directions is assumed and the specified cross-sectional shape is retained. This setting can lead to incorrect physical results for non-circular cross-sectional geometries experiencing high pressure compared to atmospheric pressure. When modelling flexible walls, the Volumetric expansion specification parameters can be used to control the method of specifying the volumetric expansion of the pipe cross-sectional area.
If the Volumetric expansion specification parameters are set to `Cross-sectional area vs. pressure', the volume change is modelled as follows:
where
;
- is the length of the pipe, the value of the Pipe length parameters;
- the nominal cross-sectional area of the pipe, defined for each shape;
- current cross-sectional area of the pipe;
- internal pressure in the pipe;
- atmospheric pressure;
- pipe deformation coefficient as a function of area, value of the parameter Static gauge pressure to cross-sectional area gain.
To calculate under the assumption of uniform elastic deformation of a thin-walled cylindrical pipe with an open end, use:
where is the wall thickness of the tube and is the Young’s modulus;
- is the pipe deformation time constant, the value of the parameter Volumetric expansion time constant.
If the Volumetric expansion specification parameters are set to Cross-sectional area vs. pressure - Tabulated, the block uses the same equation as for Cross-sectional area vs. pressure to calculate . The value is determined using the table lookup function:
where
- is the overpressure vector Static gauge pressure vector;
- cross sectional area gain vector Cross sectional area gain vector.
If the Volumetric expansion specification parameters are set to Hydraulic diameter vs. pressure, the volume change is modelled as follows:
where
;
- is the nominal hydraulic diameter determined for each mould.
- is the current hydraulic diameter of the pipe.
- pipe deformation coefficient as a function of diameter Static gauge pressure to hydraulic diameter gain.
To calculate assuming uniform elastic deformation of a thin-walled cylindrical pipe with an open end, use:
If the Volumetric expansion specification parameter is set to Based on material properties, the block uses the same equation for as for Hydraulic diameter vs. pressure, but calculates depending on the value of the Material behaviour parameter:
This parameterization assumes a cylindrical thin-walled pressure vessel, where .
If Linear elastic is selected for the Material behaviour parameters, then
where
- Young’s modulus Young’s modulus;
- Poisson’s ratio Poisson’s ratio;
where is the pipe wall thickness Pipe wall thickness;
.
If `Multilinear elastic' is selected for the Material behaviour parameters, the block calculates the von Mises stress , which is simplified to , to determine the equivalent strain. The circumferential strain is
where
block calculates Young’s modulus from the first elements of the stress vector Stress vector and strain vector Strain vector;
, where and are the equivalent total stress and equivalent total strain, respectively. The block calculates the equivalent total strain from the von Mises stress and the strain-stress curve;
, where are the elements of the Cauchy stress tensor.
If you are not modelling flexible walls, and .
Pipe with circular cross-section
The nominal hydraulic diameter and the Pipe diameter are the same.
The cross-sectional area of the pipe bore is .
Pipe with annular cross-section
The nominal hydraulic diameter is the difference between the Pipe outer diameter and the Pipe inner diameter: .
The cross-sectional area of the pipe is .
Pipe with rectangular cross-section
The nominal hydraulic diameter is:
where
- is the width of the pipe cross-section Pipe height;
- is the height of the pipe cross-section Pipe width.
The cross-sectional area of the pipe bore is .
Pipe with elliptical cross-section
The nominal hydraulic diameter is:
where
- is the major axis of the elliptical cross-section Pipe major axis;
- is the minor axis of the elliptical cross-section Pipe minor axis.
The cross-sectional area of the pipe bore is .
Pipe with isosceles triangle cross-section
The nominal hydraulic diameter is:
where
- is the triangle side length Pipe side length.
- is the angle at the vertex of the triangle Pipe vertex angle.
The cross-sectional area of the pipe bore is .
Pressure loss due to friction
Haaland’s ratio
Haaland’s analytical relation models the loss due to wall friction either by means of a cumulative equivalent length, which accounts for drag due to inhomogeneities either by adding the length of straight pipe, resulting in equivalent losses, or by means of a local loss factor, which uses a loss factor to account for pipe inhomogeneities.
If the Local resistances specification parameters are set to Aggregate equivalent length and the Reynolds number is below the Laminar flow upper Reynolds number limit, then the pressure loss across all pipe segments is:
where
- kinematic viscosity of the fluid;
- loss factor for calculation of local resistance (Darcy friction factor) in laminar flow regime Laminar friction constant for Darcy friction factor, which can be set if Cross-sectional geometry is set to Custom, otherwise it is equal to 64;
- hydraulic diameter of the pipe.
- pipe length for calculating equivalent losses, the value of the parameter Aggregate equivalent length of local resistances;
- mass flow rate at port A;
- mass flow rate at port B.
When the Reynolds number is greater than Turbulent flow lower Reynolds number limit, the pressure loss in the pipe is:
where
- Darcy’s coefficient of friction. This coefficient is approximated by the empirical Haaland equation and is based on the surface roughness , Surface roughness specification, and the hydraulic diameter of the pipe:
Pipe roughness for brass, lead, copper, plastic, steel, wrought iron and galvanised steel or iron is provided as ASHRAE standard values. You can also provide your own Internal surface absolute roughness values using the `Custom' setting.
- internal fluid density.
If the Local resistances specification parameters are set to Local loss coefficient and the Reynolds number is less than the Laminar flow upper Reynolds number limit, the pressure loss across all pipe segments is:
When the Reynolds number is greater than the Turbulent flow lower Reynolds number limit, the pressure loss in the pipe is:
where is the loss coefficient, which can be defined in the Total local loss coefficient parameters either as a single coefficient or as the sum of all loss coefficients along the pipe.
Dependence of nominal pressure drop on nominal mass flow rate
When the Viscous friction parameterization is set to Nominal pressure drop vs. nominal mass flow rate, the losses are determined using the loss coefficient for rigid or flexible walls. When the fluid is incompressible, the pressure loss across the pipe due to wall friction is:
where
- pressure drop to calculate the loss factor Nominal pressure drop as a scalar or vector;
- mass flow rate to calculate the loss factor Nominal mass flow rate as a scalar or vector.
If parameters Nominal pressure drop and Nominal mass flow rate are given as vectors, the scalar value is determined from vector elements by least squares approximation.
Table data - Darcy friction coefficient as a function of Reynolds number
If the Viscous friction parameterization parameter is set to Tabulated data - Darcy friction factor vs. Reynolds number, the viscous friction pressure losses are determined from user provided tabulated data for the Darcy friction factor vector and Reynolds number vector for turbulent Darcy friction factor parameters. Linear interpolation is used between data points.
Pipe discretisation
You can divide a pipe into multiple segments. If the pipe consists of more than one segment, the mass flow balance and momentum conservation equations are calculated for each segment.
If you want to capture specific phenomena in your application, such as water hammer, choose as many segments as will provide sufficient transient resolution. The following formula, derived from Nyquist’s discretisation theorem, is a rule of thumb for discretising a pipe by the minimum number of segments :
where
- pipe length Pipe length;
- transient frequency;
- sound velocity.
Conservation of momentum
If the Fluid dynamic compressibility checkbox is not selected, the mass flow rate at the pipe inlet is equal to the mass flow rate at the pipe outlet:
If Fluid dynamic compressibility is checked and Flexible pipe wall is unchecked, the difference between the mass flow rates at the inlet and outlet of the pipe depends on the change in fluid density due to compressibility:
If the Fluid dynamic compressibility checkbox is checked and the Flexible pipe wall checkbox is unchecked, the difference between the mass flow rates at the inlet and outlet of the pipe depends on the change in fluid density due to compressibility and the amount of fluid accumulated in the newly deformed areas of the pipe:
The change in momentum between the inlet and outlet of the pipe includes the change in pressure due to pipe wall friction, which is modelled according to Viscous friction parameterization and pipe height.
If Fluid inertia is not checked, the momentum balance will be:
where
- is the pressure in the port A;
- is the internal pressure in the liquid volume;
- port pressure B;
- pressure loss due to wall friction, parameterised by the Viscous friction losses specification for the respective port;
- pipe elevation. In the case of constant height pipes this is the parameter Elevation gain from port A to port B, otherwise it is taken as a scalar at port EL.
- Free fall acceleration. In case of fixed gravitational constant, this is the Gravitational acceleration parameter, otherwise it is taken as a scalar in port G.
If Fluid inertia is checked, the momentum balance will be:
where
- is the acceleration of the fluid in the corresponding port;
- is the cross-sectional area of the pipe port.
Ports
Conserving
# A
—
Fluid inlet or outlet port
isothermal liquid
Details
The isothermal liquid port corresponds to the inlet or outlet of the pipe.
Program usage name
port_a
# B
—
fluid inlet or outlet port
isothermal liquid
Details
The isothermal liquid port corresponds to the inlet or outlet of the pipe.
Variable lift from port A to port B as a scalar. The value at this port is limited between and , where is the pipe length, the value of the Pipe length parameters.
Dependencies
To use this port, select the Controlled elevation gain checkbox.
The variable acceleration of free fall given as a physical signal.
Dependencies
To use this port, select the Controlled graviational acceleration checkbox.
Data types
Float64.
Complex numbers support
No
Parameters
Configuration
#Fluid dynamic compressibility —
accounting for dynamic compressibility of the fluid
Details
Determines whether the dynamic compressibility of the fluid is taken into account. If Fluid dynamic compressibility is checked, changes due to the mass flow rate of the fluid in the block are calculated in addition to density changes due to pressure changes. In the isothermal liquid library, all blocks calculate density as a function of pressure.
The number of pipe divisions. Each division is a separate segment for which the pressure is calculated, depending on the pressure at the pipe inlet, the compressibility of the fluid and the flexibility of the walls, if taken into account. The volume of fluid in each segment remains fixed.
Default value
1
Program usage name
segment_count
Evaluatable
Yes
#Pipe length —
pipe length
m | cm | ft | in | km | mi | mm | um | yd
The geometry of the pipe cross-section. The nominal hydraulic diameter and nominal cross-sectional area are calculated from the cross-sectional geometry.
#Hydraulic diameter —
hydraulic diameter
m | cm | ft | in | km | mi | mm | um | yd
Details
The hydraulic diameter used in calculating the Reynolds number of a pipe. For non-round pipes, the hydraulic diameter is the diameter of an equivalent cylindrical pipe with the same cross-sectional area. For round pipes, the hydraulic diameter and the pipe diameter are the same.
Dependencies
To use this parameter, set the Cross-sectional geometry parameter to `Custom'.
Values
m | cm | ft | in | km | mi | mm | um | yd
Default value
0.1128 m
Program usage name
hydraulic_diameter
Evaluatable
Yes
#Controlled elevation gain —
pipe lifting specification
Details
If this checkbox is not selected, the pipe elevation gain from port A to B is constant and is specified in the Elevation gain from port A to port B parameters.
If this checkbox is selected, the elevation gain is variable and is taken as a scalar in port EL.
Default value
false (switched off)
Program usage name
controlled_elevation
Evaluatable
No
#Elevation gain from port A to port B —
constant pipe lift height
m | cm | ft | in | km | mi | mm | um | yd
Details
Constant pipe lifting height.
Dependencies
To use this parameter, uncheck the Controlled elevation gain box.
#Viscous friction parameterization —
method for calculating pressure loss due to wall friction
Nominal pressure drop vs. nominal mass flow rate | Haaland correlation | Tabulated data - Darcy friction factor vs. Reynolds number
Details
Parameterization of pressure loss due to wall friction. Both analytical and tabular formulations are available.
Values
Nominal pressure drop vs. nominal mass flow rate | Haaland correlation | Tabulated data - Darcy friction factor vs. Reynolds number
Default value
Haaland correlation
Program usage name
pressure_loss_type
Evaluatable
No
#Nominal mass flow rate —
mass flow rate for calculating the loss factor
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Details
The nominal mass flow rate used to calculate the pressure drop coefficient for rigid and flexible pipes is specified as a scalar or vector. All nominal values must be greater than 0 and have the same number of elements as the Nominal pressure drop parameters. If this parameter is specified as a vector, the scalar value is determined by least squares approximation.
Dependencies
To use this parameter, set the Viscous friction parameterization to `Nominal pressure drop vs. nominal mass flow rate'.
Values
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Default value
[0.1, 1.0] kg/s
Program usage name
mdot_nominal_vector
Evaluatable
Yes
#Nominal pressure drop —
Pressure drop for calculating the loss factor
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
The nominal pressure drop used to calculate the pressure loss coefficient for rigid and flexible pipes is specified as a scalar or vector. All nominal values must be greater than 0 and have the same number of elements as the Nominal mass flow rate parameters. If this parameter is specified as a vector, the scalar value is determined by least squares approximation.
Dependencies
To use this parameter, set the Viscous friction parameterization to `Nominal pressure drop vs. nominal mass flow rate'.
Values
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Default value
[0.001, 0.01] MPa
Program usage name
delta_p_nominal_vector
Evaluatable
Yes
#Mass flow rate threshold for flow reversal —
mass flow threshold
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Details
The mass flow threshold value for reversible flow. Between the positive and negative values of the mass flow threshold a transition region around 0 kg/s is defined. Within this transition region, numerical smoothing is applied to the flow response. The threshold value must be greater than `0.
Dependencies
To use this parameter, set the Viscous friction parameterization parameters to `Nominal pressure drop vs. nominal mass flow rate'.
Values
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Default value
1e-6 kg/s
Program usage name
mdot_threshold
Evaluatable
Yes
#Local resistances specification —
method for quantifying pressure losses in the Haaland ratio
Aggregate equivalent length | Local loss coefficient
Details
A method for quantifying pressure losses due to pipe inhomogeneity.
Dependencies
To use this parameter, set the Viscous friction parameterization parameter to `Haaland correlation'.
Values
Aggregate equivalent length | Local loss coefficient
Default value
Aggregate equivalent length
Program usage name
local_pressure_loss_type
Evaluatable
No
#Aggregate equivalent length of local resistances —
pipe length for calculation of equivalent losses
m | cm | ft | in | km | mi | mm | um | yd
Details
The length of pipe that will result in equivalent hydraulic losses as a pipe with bends, area changes or other non-uniform characteristics. The effective pipe length is equal to the sum of Pipe length and Aggregate equivalent length of local resistances.
Dependencies
To use this parameter, set the Viscous friction parameterization parameter to `Haaland correlation' and the Local resistance specifications parameter to `Aggregate equivalent length'.
The loss factor associated with each irregularity in the pipe. You can enter a single loss factor or the sum of all loss factors along the pipe.
Dependencies
To use this parameter, set the Viscous friction parameterization parameter to `Haaland correlation' and the Local resistance specifications parameter to `Local loss coefficient'.
Default value
0.1
Program usage name
C_local_loss
Evaluatable
Yes
#Surface roughness specification —
pipe material for roughness determination
Commercially smooth brass, lead, copper, or plastic pipe : 1.52 um | Steel and wrought iron : 46 um | Galvanized iron or steel : 152 um | Cast iron : 259 um | Custom
Details
Absolute surface roughness depending on the pipe material. The values given are ASHRAE standard roughness values. You can also enter your own value by setting the Surface roughness specification to `Custom'.
Dependencies
To use this parameter, set the Viscous friction parameterization parameter to `Haaland correlation'.
Values
Commercially smooth brass, lead, copper, or plastic pipe : 1.52 um | Steel and wrought iron : 46 um | Galvanized iron or steel : 152 um | Cast iron : 259 um | Custom
Default value
Commercially smooth brass, lead, copper, or plastic pipe : 1.52 um
Program usage name
roughness_specification
Evaluatable
No
#Internal surface absolute roughness —
pipe wall roughness
m | cm | ft | in | km | mi | mm | um | yd
Details
Absolute roughness of the pipe walls. This parameter is used to determine the Darcy friction coefficient, which contributes to the pressure loss in the pipe.
Dependencies
To use this parameter, set the Viscous friction parameterization parameter to `Haaland correlation' and the Surface roughness specification parameter to `Custom'.
Values
m | cm | ft | in | km | mi | mm | um | yd
Default value
15e-6 m
Program usage name
roughness
Evaluatable
Yes
#Reynolds number vector for turbulent Darcy friction —
vector of Reynolds numbers for tabular parameterization
Details
Reynolds number vector for tabular parameterization of the Darcy friction coefficient. The elements of the Reynolds number vector for turbulent Darcy friction correspond to the elements of the Darcy friction factor vector. The elements of the vector should be listed in ascending order. A positive Reynolds number corresponds to the flow from port A to port B.
Dependencies
To use this parameter, set the Viscous friction parameterization parameters to Tabulated data - Darcy friction factor vs. Reynolds number.
#Darcy friction factor vector —
vector of friction coefficients for tabular parameterization
Details
Darcy friction factor vector for tabular parameterization of Darcy friction factor. The elements of the Darcy friction factor vector correspond to the elements of the Reynolds number vector for turbulent Darcy friction factor. The elements of the vector must be unique and greater than or equal to `0'.
Dependencies
To use this parameter, set the Viscous friction parameterization parameters to Tabulated data - Darcy friction factor vs. Reynolds number.
#Laminar flow upper Reynolds number limit —
upper limit of Reynolds number in the laminar flow regime
Details
Upper limit of the Reynolds number in the laminar flow regime. Beyond this number, the flow regime becomes transient, approaches the turbulent regime and becomes fully turbulent at the Turbulent flow lower Reynolds number limit.
Dependencies
To use this parameter, set the Viscous friction parameterization to one of the following values:
`Haaland correlation
`Tabulated data - Darcy friction factor vs. Reynolds number
Default value
2000.0
Program usage name
Re_laminar
Evaluatable
Yes
#Turbulent flow lower Reynolds number limit —
lower limit of Reynolds number in turbulent flow regime
Details
The lower limit value of the Reynolds number in the turbulent flow regime. Below this number, the flow regime is transient, approaches laminar and becomes fully laminar on the Laminar flow upper Reynolds number limit page.
Dependencies
To use this parameter, set the Viscous friction parameterization to one of the following values:
`Haaland correlation
`Tabulated data - Darcy friction factor vs. Reynolds number
Default value
4000.0
Program usage name
Re_turbulent
Evaluatable
Yes
#Laminar friction constant for Darcy friction factor —
loss coefficient for calculation of local resistance (Darcy coefficient) in laminar flow regime
Details
loss coefficient for calculating the Darcy coefficient in laminar flow regime. The Darcy friction coefficient takes into account the contribution of wall friction in pressure loss calculations. If Cross-sectional geometry is not set to `Custom', the value of this parameter is `64'.
Dependencies
To use this parameter, set the Viscous friction parameterization to one of the following values:
`Haaland correlation
`Tabulated data - Darcy friction factor vs. Reynolds number
And set the Cross-sectional geometry parameters to Custom.
If this box is checked, uniform expansion along all directions is assumed and the specified cross-sectional shape is retained. This may not be accurate for non-circular cross-sectional geometries under severe deformation.
Dependencies
To use this parameter, select Fluid dynamic compressibility.
Default value
false (switched off)
Program usage name
wall_flexibility
Evaluatable
No
#Volumetric expansion specification —
method of specifying the volumetric expansion of the pipe cross-sectional area
Cross-sectional area vs. pressure | Cross-sectional area vs. pressure - Tabulated | Hydraulic diameter vs. pressure | Based on material properties
Details
The settings for this parameter relate the new cross-sectional area or hydraulic diameter to the pressure in the pipe.
Dependencies
To use this parameters, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox.
Values
Cross-sectional area vs. pressure | Cross-sectional area vs. pressure - Tabulated | Hydraulic diameter vs. pressure | Based on material properties
Default value
Cross-sectional area vs. pressure
Program usage name
volumetric_expansion_model
Evaluatable
No
#Static gauge pressure to cross-sectional area gain —
pipe deformation coefficient as a function of area
m^2/MPa
Details
Coefficient for calculating pipe deformation when the Volumetric expansion specification is set to Cross-sectional area vs. pressure. The coefficient is multiplied by the pressure drop between segmental pressure and atmospheric pressure.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, and set the Volumetric expansion specification parameters to `Cross-sectional area vs. pressure'.
Values
m^2/MPa
Default value
1e-6 m^2/MPa
Program usage name
area_to_static_gauge_pressure_gain_const
Evaluatable
Yes
#Static gauge pressure vector —
overpressure vector
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
A vector containing overpressure values. The block uses this vector in the table to calculate the cross-sectional area of the pipe bore. The elements of the vector must be strictly positive and monotonically increasing, and the dimensionality of the vector must match the dimensionality of the Cross sectional area gain vector.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, and set the Volumetric expansion specification parameters to `Cross-sectional area vs. pressure - Tabulated'.
Values
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Default value
[0.1, 1.0] MPa
Program usage name
static_gauge_pressure_vector
Evaluatable
Yes
#Cross sectional area gain vector —
vector of cross-sectional areas of pipe bores
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Details
A vector containing the cross-sectional areas of pipe bores. The block uses this vector in the table to calculate the cross-sectional area of a pipe bore at other pressures. The elements of the vector must be strictly positive and monotonically increasing, and the dimensionality of the vector must coincide with the dimensionality of the Static gauge pressure vector.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, and set the Volumetric expansion specification parameters to `Cross-sectional area vs. pressure - Tabulated'.
#Static gauge pressure to hydraulic diameter gain —
pipe deformation coefficient depending on diameter
m/MPa
Details
Coefficient for calculating pipe deformation when the Volumetric expansion specification is set to Hydraulic diameter vs. pressure. The coefficient is multiplied by the pressure drop between segment pressure and atmospheric pressure.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, and set the Volumetric expansion specification parameters to Hydraulic diameter vs. pressure.
#Material behavior —
the method used to specify the behaviour of the material
Linear Elastic | Multilinear Elastic
Details
The method the block uses to calculate the material behaviour.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, and set the Volumetric expansion specification parameters to `Based on material properties'.
Values
Linear Elastic | Multilinear Elastic
Default value
Linear Elastic
Program usage name
material_behavior_model
Evaluatable
No
#Pipe wall thickness —
pipe wall thickness
m | cm | ft | in | km | mi | mm | um | yd
Details
The wall thickness of the pipe. The block uses this value to calculate the stress.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, and set the Volumetric expansion specification parameters to `Based on material properties'.
Values
m | cm | ft | in | km | mi | mm | um | yd
Default value
0.05 m
Program usage name
wall_thickness
Evaluatable
Yes
#Young's modulus —
Young’s modulus of pipe wall material
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
Young’s modulus of the pipe wall material.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, set the Volumetric expansion specification to `Based on material properties' and the Material behaviour parameters to `Linear Elastic'.
Values
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Default value
69.0 GPa
Program usage name
E
Evaluatable
Yes
#Stress vector —
stress vector of pipe wall material
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
A vector containing the stress values for the pipe wall material.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, set the Volumetric expansion specification to `Based on material properties' and the Material behaviour parameter to `Multilinear Elastic'.
Values
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Default value
[276.0, 310.0] MPa
Program usage name
stress_vector
Evaluatable
Yes
#Strain vector —
deformation vector of pipe wall material
Details
A vector containing the strain values for the pipe wall material.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, set the Volumetric expansion specification to `Based on material properties' and the Material behaviour parameters to `Multilinear Elastic'.
Default value
[0.004, 0.02]
Program usage name
strain_vector
Evaluatable
Yes
#Check if stress exceeds allowable level —
notification when the voltage exceeds the set maximum
None | Error
Details
The value of this parameter determines the behaviour of the unit when the voltage exceeds the maximum voltage specified by the Maximum allowable stress parameters.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, set the Volumetric expansion specification to `Based on material properties' and the Material behaviour parameters to `Multilinear Elastic'.
Values
None | Error
Default value
None
Program usage name
stress_assert_action
Evaluatable
No
#Maximum allowable stress —
maximum allowable stress on the pipe wall
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
The maximum stress that is allowed on the pipe wall. Control what the unit will do if the stress exceeds this value using the Check if stress exceeds specified allowable level parameters.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, set the Volumetric expansion specification to `Based on material properties', the Material behaviour parameter to `Multilinear Elastic', and the Check if stress exceeds specified allowable level parameter to `Error'.
Values
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Default value
400.0 MPa
Program usage name
max_stress
Evaluatable
Yes
#Poisson's ratio —
Poisson’s ratio of pipe wall material
Details
Poisson’s ratio of the pipe wall material.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox, and set the Volumetric expansion specification parameters to `Based on material properties'.
Default value
0.33
Program usage name
poisson_ratio
Evaluatable
Yes
#Volumetric expansion time constant —
time constant of pipe deformation
d | s | hr | ms | ns | us | min
Details
The time required for the wall to reach a steady state after deformation of the pipe. This parameter affects the dynamic change of the pipe volume.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Flexible pipe wall checkbox.
Values
d | s | hr | ms | ns | us | min
Default value
0.01 s
Program usage name
volumetric_expansion_time_constant
Evaluatable
Yes
Initial Conditions
#Initial liquid pressure —
initial pressure in the pipe or pipe segment
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Details
The initial fluid pressure, specified as a scalar or vector. A vector of length elements defines the fluid pressure for each of the pipe segments. If the vector length is two elements, the pressure along the pipe is linearly distributed between the two element values. If the vector length is three or more elements, the initial pressure in -th segment is determined by -th element of the vector.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox.
Values
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Default value
0.101325 MPa
Program usage name
p_start
Evaluatable
Yes
#Initial mass flow rate from port A to port B —
initial mass flow rate for inertia calculation
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Details
Initial mass flow rate for pipes with modelled fluid inertia.
Dependencies
To use this parameter, select the Fluid dynamic compressibility checkbox and the Fluid inertia checkbox.
Values
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Default value
0.0 kg/s
Program usage name
mdot_start
Evaluatable
Yes
Literature
Budynas R. G. Nisbett J. K. & Shigley J. E. (2004). Shigley’s mechanical engineering design (7th ed.). McGraw-Hill.
Ju Frederick D., Butler Thomas A., Review of Proposed Failure Criteria for Ductile Materials (1984) Los Alamos National Laboratory.
Jahed H, A Variable Material Property Approach for Elastic-Plastic Analysis of Proportional and Non-proportional Loading, (1997) University of Waterloo