Partial model for a flow resistance, possible with variable flow coefficient.
Models that extend this class need to implement an equation that relates
m_flow
and dp
, and they need to assign the parameter
m_flow_turbulent
.
See for example
IBPSA.Fluid.FixedResistances.PressureDrop for a model that extends
this base class.

November 3, 2016, by Michael Wetter:
Removed start value for pressure difference
to simplify the parameter window.
This is for
#552.

January 26, 2016, by Michael Wetter:
Avoided assignment of dp(nominal=0)
if dp_nominal_pos = 0
and of m_flow(nominal=0)
if m_flow_nominal_pos = 0
as nominal values are not allowed to be zero.

January 22, 2016, by Michael Wetter:
Corrected type declaration of pressure difference.
This is
for #404.

August 15, 2015, by Filip Jorissen:
Implemented more efficient computation of port_a.Xi_outflow
,
port_a.h_outflow
and port_a.C_outflow
when allowFlowReversal=false
.
This is for
#281.

January 13, 2015, by Marcus Fuchs:
Revised revisions section (there were two revisions statements)

November 20, 2014 by Michael Wetter:
Removed start
attribute for m_flow
as this is already set in its base class.

October 8, 2013 by Michael Wetter:
Removed propagation of show_V_flow
to base class as it has no longer this parameter.

December 14, 2012 by Michael Wetter:
Renamed protected parameters for consistency with the naming conventions.

February 12, 2012, by Michael Wetter:
Removed duplicate declaration of m_flow_nominal
.

February 3, 2012, by Michael Wetter:
Made assignment of m_flow_small
final
as it is no
longer used in the base class.

January 16, 2012, by Michael Wetter:
To simplify object inheritance tree, revised base classes
IBPSA.Fluid.BaseClasses.PartialResistance
,
IBPSA.Fluid.Actuators.BaseClasses.PartialTwoWayValve
,
IBPSA.Fluid.Actuators.BaseClasses.PartialDamperExponential
,
IBPSA.Fluid.Actuators.BaseClasses.PartialActuator
and model
IBPSA.Fluid.FixedResistances.PressureDrop
.

August 5, 2011, by Michael Wetter:
Moved linearized pressure drop equation from the function body to the equation
section. With the previous implementation,
the symbolic processor may not rearrange the equations, which can lead
to coupled equations instead of an explicit solution.

June 20, 2011, by Michael Wetter:
Set start values for m_flow
and dp
to zero, since
most HVAC systems start at zero flow. With this change, the start values
appear in the GUI and can be set by the user.

April 2, 2011 by Michael Wetter:
Added m_flow_nominal_pos
and dp_nominal_pos
to allow
providing negative nominal values which will be used, for example, to set start
values of flow splitters which may have negative flow rates and pressure drop
at the initial condition.

March 27, 2011, by Michael Wetter:
Added homotopy
operator.

March 23, 2011 by Michael Wetter:
Added homotopy operator.

March 30, 2010 by Michael Wetter:
Changed base classes to allow easier initialization.

April 13, 2009, by Michael Wetter:
Extracted pressure drop computation and implemented it in the
new model
IBPSA.Fluid.BaseClasses.FlowModels.BasicFlowModel.

September 18, 2008, by Michael Wetter:
Added equations for the mass balance of extra species flow,
i.e., C
and mC_flow
.

July 20, 2007 by Michael Wetter:
First implementation.
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