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

This component models a generic resistance parameterized with the volume flow rate:

    dp     = a*V_flow^2 + b*V_flow
    m_flow = rho*V_flow

with

a	as quadratic coefficient [Pa*s^2/m^6],
b	as linear coefficient [Pa*s/m3],
dp	as pressure loss [Pa],
m_flow	as mass flow rate [kg/s],
rho	as density of fluid [kg/m3],
V_flow	as volume flow rate [m3/s].

The geometry parameters of energy devices necessary for the pressure loss calculations are often not exactly known. Therefore the modelling of the detailed pressure loss calculation has to be simplified. This components use a linear and a quadratic dependence of the pressure loss on the volume flow rate. It is assumed that neither mass nor energy is stored in this component. In the model basically a function is called to compute the mass flow rate as a function of pressure loss. Also the inverse of this function is defined, and a tool might use this inverse function instead, in order to avoid the solution of a nonlinear equation.

The details of the model are described in the documentation of the underlying function.

allowFlowReversal	Value: system.allowFlowReversal Type: Boolean Description: = true to allow flow reversal, false restricts to design direction (port_a -> port_b)
dp_start	Value: 0.01 * system.p_start Type: AbsolutePressure (Pa) Description: Guess value of dp = port_a.p - port_b.p
m_flow_start	Value: system.m_flow_start Type: MassFlowRate (kg/s) Description: Guess value of m_flow = port_a.m_flow
m_flow_small	Value: if system.use_eps_Re then system.eps_m_flow * system.m_flow_nominal else system.m_flow_small Type: MassFlowRate (kg/s) Description: Small mass flow rate for regularization of zero flow
show_T	Value: true Type: Boolean Description: = true, if temperatures at port_a and port_b are computed
show_V_flow	Value: true Type: Boolean Description: = true, if volume flow rate at inflowing port is computed
a	Value: Type: Real ((Pa·s²)/m6) Description: Coefficient for quadratic term
b	Value: Type: Real ((Pa·s)/m³) Description: Coefficient for linear term