Several problems have to be analysed. The first one is studying the effect of the ventilation system over the security of the passengers because of the fire. Hence, the problem mainly comes from the temperature and the smoke, which are a big danger for people. However, it is obvious that the smoke and the temperature will have a same pattern into the tunnel (when the smoke is high the temperature will be high as well and reciprocally). Also, the flow direction depends on the pressure into the tunnel. Therefore, the flow direction and pressure are linked as we have seen in the first part. Also, the pressure pattern has an influence in the temperature variation. The pressure difference will push away the warm temperature, hence the smoke and warm air are depending of the pressure difference and flow direction.

As said previously, the two main variables are the smoke and temperature, because they describe the most dangerous situation for the passengers. During the analysis, many other points have been noticed. In the train station, the air coming inside spins in an angle of 90° which creates a huge vorticity and turbulent flow at this place. It causes a probable problem of efficiency because the fluid is not going directly into the tunnel. Also, at the rear part of the wagon, the air flow is turbulent (because of the increased temperature and the shape of the system) but it was not an important remark. An important thing was the flow direction, because it will explain the flow movement into the tunnel. However, to make a visualization picture one needs to chose the most important variable.

After decomposition of the problem and abstraction of important information, we should design an step by step solution for our visulization problem. First, we should have a deep understanding of our problem. We can do this by changing the colours of the flow for important parameters like temperature and smoke to see the difference. Actually, we have done this by the first part of our course mini-project. In that part, we have studied our problem in a scientific way in order figure out the behaviour of flow, streamlines, etc. The second step is to make the important parts distinguishable. So, we have used yellow color for the train and the station to make them more distinguishable from the environment. Moreover, to show that they should reach each other and to use the danger color (yellow). The third step is to visualize the important parameters. As mentioned before, for our problem, the most important parameters for passengers survival, are smoke concentration and temperature. To clearly show the smoke , we have used gray and black color. To visualize the temperature, we have painted the streamlines to show the ventilation system's effect on the temperature distribution as well. The last step is to make our picture more clear and artistic. for this part, we have used the tube option to make the streamlines more attractive. Also, we used a gradient for the background of our image with a bright color. At the end, we have put the camera near the train and the station at the back, to show the aim of passengers to arrive to the station safely.