WOLFRAM SYSTEM MODELER
pressureLoss_m_flow_and_ReReturn pressure drop from constant loss factor, mass flow rate and Re (dp = f(m_flow)) |
SystemModel["Modelica.Fluid.Fittings.BaseClasses.QuadraticTurbulent.pressureLoss_m_flow_and_Re"]
This information is part of the Modelica Standard Library maintained by the Modelica Association.
Compute pressure drop from constant loss factor and mass flow rate (dp = f(m_flow)). If the Reynolds-number Re ≥ data.Re_turbulent, the flow is treated as a turbulent flow with constant loss factor zeta. If the Reynolds-number Re < data.Re_turbulent, the flow is laminar and/or in a transition region between laminar and turbulent. This region is approximated by two polynomials of third order, one polynomial for m_flow ≥ 0 and one for m_flow < 0. The common derivative of the two polynomials at Re = 0 is computed from the equation "data.c0/Re".
If no data for c0 is available, the derivative at Re = 0 is computed in such a way, that the second derivatives of the two polynomials are identical at Re = 0. The polynomials are constructed, such that they smoothly touch the characteristic curves in the turbulent regions. The whole characteristic is therefore continuous and has a finite, continuous first derivative everywhere. In some cases, the constructed polynomials would "vibrate". This is avoided by reducing the derivative at Re=0 in such a way that the polynomials are guaranteed to be monotonically increasing. The used sufficient criteria for monotonicity follows from:
m_flow |
Type: MassFlowRate (kg/s) Description: Mass flow rate from port_a to port_b |
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rho_a |
Type: Density (kg/m³) Description: Density at port_a |
rho_b |
Type: Density (kg/m³) Description: Density at port_b |
mu_a |
Type: DynamicViscosity (Pa⋅s) Description: Dynamic viscosity at port_a |
mu_b |
Type: DynamicViscosity (Pa⋅s) Description: Dynamic viscosity at port_b |
data |
Type: LossFactorData Description: Constant loss factors for both flow directions |
dp |
Type: Pressure (Pa) Description: Pressure drop (dp = port_a.p - port_b.p) |
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