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# Modelling longitudinal waves in a long train-set

- Introduction
- Download the example
- Run the runf/long_train_Ccoupl.tsimf
- Examine the results in GPLOT

## Introduction

The train-set consists of one locomotive m_loco pulling 36 wagons m_wagon_tare carrying load m_load. The train-set enters an upwards slope which causes a retardation of the locomotive which compresses the train-set. On top of the upward slope max power on the locomotive is applied which pulls all wagons apart again. When the acceleration wave reaches the last wagon of the train-set, the longitudinal acceleration has grown into a level which causes sliding of its load.

## Download the example

- Download the tar-file long_train.tgz
  - List the contents of the tar-file: `tar -tzvkpf long_train.tgz`
  - Extract the contents of the tar-file: `tar -xzvkpf long_train.tgz`
- or the zip-file long_train.zip
  - List the contents of the tar-file: `unzip -l long_train.zip`
  - Extract the contents of the tar-file: `unzip long_train.zip`
- or go directly to the files: long_train

## Run the example runf/long_train_Ccoupl.tsimf

- Double-click file runf/long_train_Ccoupl.tsimf and select open->run with the right mouse button.
- As output the following files will be produced:

  id/long_train_Ccoupl.id | MPdat-file for plotting in MPLOT
  gp/long_train_Ccoupl.gp | GPdat-file for animation in GPLOT

## Examine the results in postprocessor GPLOT

- Double-click directory runf/ in the subdirectory text area.
- Double-click file runf/long_train_Ccoupl.tsimf in the file text area.
- Press the Gplot-pushbutton.
- Open file gp/long_train_Ccoupl.gp by selecting File->read_GPdat in the pulldown menu bar
- Select View->view_side from the pulldown menu bar
- Click View->show_1_diag and set "Deformation scale fact" to 25 approximately.
- Zoom out by pressing the left mouse button and drag the mouse downwards, or use the roller on your mouse.
- Start the animation by pressing the Fwd–pushbutton.
- The observer moves at constant speed Vo. If the speed of the observer does not agree with the speed of the train-set the model can be moved longitudinally by pressing the right mouse button and drag the mouse to the left or to the right.
- Observe the last wagon and its load when the acceleration wave reaches the end of the train-set

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