AixLib.Fluid.BaseClasses.IndexMassFraction

# .AixLib.Fluid.BaseClasses.IndexMassFraction

Computes the index of a substance in the mass fraction vector Xi

## Information

This block computes the index that the subtance with name `substanceName` has in the mass fraction vector `X`. If the medium model has no component called `substanceName`, then the block writes an error message and terminates the simulation.

This block is used for example to obtain the index of the subtance 'water' to obtain the water vapor concentration, or to measure any other mass fraction.

## Contents

Name | Description
--- | ---
Medium | Medium model

## Revisions

- November 14, 2019, by Michael Wetter:
  Rewrote assignment of `i_x` to avoid a variable array index.
  This is for #1250.
- January 18, 2019, by Jianjun Hu:
  Limited the media choice to moist air only. See #1050.
- August 31, 2013, by Michael Wetter:
  Revised the model and added the parameter `substanceName`.
- December 18, 2012, by Michael Wetter:
  First implementation.

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