Annex60.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow

# .Annex60.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow

Function that computes pressure drop for given mass flow rate

## Information

Function that computes the pressure drop of flow elements as

Δp = sign(m) (m ⁄ k)2

with regularization near the origin. Therefore, the flow coefficient is

k = m ⁄ √ Δp

The input `m_flow_turbulent` determines the location of the regularization.

#### Interface

>     function basicFlowFunction_m_flow
>       input Modelica.SIunits.MassFlowRate m_flow "Mass flow rate in design flow direction";
>       input Real k(unit = "") "Flow coefficient, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2)";
>       input Modelica.SIunits.MassFlowRate m_flow_turbulent(min = 0) "Mass flow rate where transition to turbulent flow occurs";
>       output Modelica.SIunits.PressureDifference dp(displayUnit = "Pa") "Pressure difference between port_a and port_b (= port_a.p - port_b.p)";
>     end basicFlowFunction_m_flow;

## Revisions

- January 22, 2016, by Michael Wetter:
  Corrected type declaration of pressure difference. This is for #404.
- July 28, 2015, by Michael Wetter:
  Removed double declaration of `smooth(..)` and `smoothOrder` and changed `Inline=true` to `LateInline=true`. This is for issue 301.
- July 15, 2015, by Filip Jorissen:
  New, more efficient implementation based on regularisation using simple polynomial. Expanded common subexpressions for function inlining to be possible. Set `Inline=true` for inlining to occur. This is for #279.
- August 10, 2011, by Michael Wetter:
  Removed `if-then` optimization that set `dp=0` if `m_flow=0`, as this causes the derivative to be discontinuous at `m_flow=0`.
- August 4, 2011, by Michael Wetter:
  Removed option to use a linear function. The linear implementation is now done in models that call this function. With the previous implementation, the symbolic processor may not rearrange the equations, which can lead to coupled equations instead of an explicit solution.
- April 13, 2009, by Michael Wetter:
  First implementation.

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