PartialGenericPipeFlowGenericPipeFlow: Pipe flow pressure loss and gravity with replaceable WallFriction package 
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 nonlinear 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 speedup the simulation and/or might give a more robust simulation.
m 
Value: n  1 Type: Integer Description: Number of flow segments 

n 
Value: 2 Type: Integer Description: Number of discrete flow volumes 
nParallel 
Value: Type: Real Description: number of identical parallel flow devices 
g 
Value: system.g Type: Acceleration (m/s²) Description: Constant gravity acceleration 
allowFlowReversal 
Value: system.allowFlowReversal Type: Boolean Description: = true to allow flow reversal, false restricts to design direction (states[1] > states[n+1]) 
momentumDynamics 
Value: system.momentumDynamics Type: Dynamics Description: Formulation of momentum balance 
m_flow_start 
Value: system.m_flow_start Type: MassFlowRate (kg/s) Description: Start value of mass flow rates 
p_a_start 
Value: Type: AbsolutePressure (Pa) Description: Start value for p[1] at design inflow 
p_b_start 
Value: Type: AbsolutePressure (Pa) Description: Start value for p[n+1] at design outflow 
useUpstreamScheme 
Value: true Type: Boolean Description: = false to average upstream and downstream properties across flow segments 
use_Ib_flows 
Value: momentumDynamics <> Types.Dynamics.SteadyState Type: Boolean Description: = true to consider differences in flow of momentum through boundaries 
Re_turbulent 
Value: 4000 Type: ReynoldsNumber Description: Start of turbulent regime, depending on type of flow device 
show_Res 
Value: false Type: Boolean Description: = true, if Reynolds numbers are included for plotting 
from_dp 
Value: momentumDynamics >= Types.Dynamics.SteadyStateInitial Type: Boolean Description: = true, use m_flow = f(dp), otherwise dp = f(m_flow) 
dp_nominal 
Value: Type: AbsolutePressure (Pa) Description: Nominal pressure loss (only for nominal models) 
m_flow_nominal 
Value: Type: MassFlowRate (kg/s) Description: Nominal mass flow rate 
m_flow_small 
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) 
pathLengths 
Type: Length[m] (m) Description: Lengths along flow path 

states 
Type: ThermodynamicState[n] Description: Thermodynamic states along design flow 
vs 
Type: Velocity[n] (m/s) Description: Mean velocities of fluid flow 
crossAreas 
Type: Area[n] (m²) Description: Cross flow areas at segment boundaries 
dimensions 
Type: Length[n] (m) Description: Characteristic dimensions for fluid flow (diameters for pipe flow) 
roughnesses 
Type: Roughness[n] (m) Description: Average height of surface asperities 
dheights 
Type: Length[n  1] (m) Description: Height(states[2:n])  Height(states[1:n1]) 
pathLengths_internal 
Type: Length[n  1] (m) Description: pathLengths used internally; to be defined by extending class 
Res_turbulent_internal 
Default Value: Re_turbulent * ones(n  1) Type: ReynoldsNumber[n  1] Description: Re_turbulent used internally; to be defined by extending class 
system 
Type: System Description: System properties 


states 
Type: ThermodynamicState[n] Description: Thermodynamic states along design flow 
Modelica.Fluid.Pipes.BaseClasses.FlowModels DetailedPipeFlow: Detailed characteristic for laminar and turbulent flow 

Modelica.Fluid.Pipes.BaseClasses.FlowModels TurbulentPipeFlow: Quadratic turbulent flow in circular tubes (using mu to regularize laminar region) 

Modelica.Fluid.Pipes.BaseClasses.FlowModels NominalTurbulentPipeFlow: Quadratic turbulent flow in circular tubes for given nominal values 