# PartialGenericPipeFlow

GenericPipeFlow: Pipe flow pressure loss and gravity with replaceable WallFriction package

# Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

This model describes pressure losses due to wall friction in a pipe and due to gravity. Correlations of different complexity and validity can be selected via the replaceable package WallFriction (see parameter menu below). The details of the pipe wall friction model are described in the UsersGuide. Basically, different variants of the equation

```   dp = λ(Re,D)*(L/D)*ρ*v*|v|/2.
```

By default, the correlations are computed with media data at the actual time instant. In order to reduce non-linear equation systems, the parameters use_mu_nominal and use_rho_nominal provide the option to compute the correlations with constant media values at the desired operating point. This might speed-up the simulation and/or might give a more robust simulation.

# Parameters (17)

m Value: n - 1 Type: Integer Description: Number of flow segments Value: 2 Type: Integer Description: Number of discrete flow volumes Value: Type: Real Description: number of identical parallel flow devices Value: system.g Type: Acceleration (m/s²) Description: Constant gravity acceleration Value: system.allowFlowReversal Type: Boolean Description: = true to allow flow reversal, false restricts to design direction (states[1] -> states[n+1]) Value: system.momentumDynamics Type: Dynamics Description: Formulation of momentum balance Value: system.m_flow_start Type: MassFlowRate (kg/s) Description: Start value of mass flow rates Value: Type: AbsolutePressure (Pa) Description: Start value for p[1] at design inflow Value: Type: AbsolutePressure (Pa) Description: Start value for p[n+1] at design outflow Value: true Type: Boolean Description: = false to average upstream and downstream properties across flow segments Value: momentumDynamics <> Types.Dynamics.SteadyState Type: Boolean Description: = true to consider differences in flow of momentum through boundaries Value: 4000 Type: ReynoldsNumber Description: Start of turbulent regime, depending on type of flow device Value: false Type: Boolean Description: = true, if Reynolds numbers are included for plotting Value: momentumDynamics >= Types.Dynamics.SteadyStateInitial Type: Boolean Description: = true, use m_flow = f(dp), otherwise dp = f(m_flow) Value: Type: AbsolutePressure (Pa) Description: Nominal pressure loss (only for nominal models) Value: Type: MassFlowRate (kg/s) Description: Nominal mass flow rate Value: if system.use_eps_Re then system.eps_m_flow * m_flow_nominal else system.m_flow_small Type: MassFlowRate (kg/s) Description: Within regularization if |m_flows| < m_flow_small (may be wider for large discontinuities in static head)

# Inputs (9)

pathLengths Type: Length[m] (m) Description: Lengths along flow path Description: Thermodynamic states along design flow Type: Velocity[n] (m/s) Description: Mean velocities of fluid flow Type: Area[n] (m²) Description: Cross flow areas at segment boundaries Type: Length[n] (m) Description: Characteristic dimensions for fluid flow (diameters for pipe flow) Type: Roughness[n] (m) Description: Average height of surface asperities Type: Length[n - 1] (m) Description: Height(states[2:n]) - Height(states[1:n-1]) Type: Length[n - 1] (m) Description: pathLengths used internally; to be defined by extending class Default Value: Re_turbulent * ones(n - 1) Description: Re_turbulent used internally; to be defined by extending class

# Components (2)

system Type: System Description: System properties Description: Thermodynamic states along design flow

# Extended by (3)

 DetailedPipeFlow Modelica.Fluid.Pipes.BaseClasses.FlowModels DetailedPipeFlow: Detailed characteristic for laminar and turbulent flow TurbulentPipeFlow Modelica.Fluid.Pipes.BaseClasses.FlowModels TurbulentPipeFlow: Quadratic turbulent flow in circular tubes (using mu to regularize laminar region) NominalTurbulentPipeFlow Modelica.Fluid.Pipes.BaseClasses.FlowModels NominalTurbulentPipeFlow: Quadratic turbulent flow in circular tubes for given nominal values