Annex60.Airflow.Multizone.BaseClasses.PowerLawResistance

# .Annex60.Airflow.Multizone.BaseClasses.PowerLawResistance

Flow resistance that uses the power law

## Information

This model describes the mass flow rate and pressure difference relation of an orifice in the form

        V_flow = k * dp^m,

where `k` is a variable and `m` a parameter. For turbulent flow, set `m=1/2` and for laminar flow, set `m=1`.

The model is used as a base for the interzonal air flow models.

## Revisions

- January 22, 2016, by Michael Wetter:
  Corrected type declaration of pressure difference. This is for #404.
- November 19, 2015, by Michael Wetter:
  Removed assignment of parameter `showDesignFlowDirection` in `extends` statement. This is for #349.
- January 21, 2015 by Michael Wetter:
  Changed type of `mExc` as `Modelica.SIunits.Mass` sets `min=0`, but `mExc` can be negative.
- October 8, 2013 by Michael Wetter:
  Changed the parameter `useConstantDensity` to `useDefaultProperties` and also applied the parameter to the computation of the dynamic viscosity. The conversion script can be used to update this parameter.
  Change model to not use the instance `sta_a`, as this may be conditionally removed and hence it is not proper Modelica syntax to use it outside of a `connect` statement.
- March 27, 2013 by Michael Wetter:
  Added assignment of initial value for `mExc` to avoid error when checking model in pedantic mode with Dymola 2014.
- December 14, 2012 by Michael Wetter:
  Renamed protected parameters for consistency with the naming conventions.
- December 6, 2011 by Michael Wetter:
  Removed `fixed=false` attribute of protected parameter `k`.
- July 20, 2010 by Michael Wetter:
  Migrated model to Modelica 3.1 and integrated it into the Buildings library.
- February 4, 2005 by Michael Wetter:
  Released first version.

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