Adding a Streamline

 

A third option available for post-processing in:Flux visualizations is the streamline. Here a particle is followed from the starting edge of the flow and tracked while it is traveling through the domain. The particle is then colored as it travels to represent changing speed along its path. For in:Flux simulations, streamlines for ventilation simulations display the velocity magnitude of the particle as it traverses the domain.

 

To add a streamline:

  1. Click the Add Item tab and select Streamlines from the dropdown menu.

  2. Leave the Name to its automatically generated one.

  3. Select the Westerly, 5 m/s as the Simulation.

  4. Set the Direction to be Forward and Backward.

  5. Ensure that Auto-Seed is selected and enter a value of "2" as the Offset.

  6. Click the Add Item button.

 

Figure 29 shows the resulting streamline for the ventilation simulation. We can see how some of the flow is impacted by the large storage tanks, some particles travel under some of the railing and around the vertical tanks. The legend in Figure 29 was 'linked' to the streamlines by right-clicking the streamlines text in the project items tab and selecting Link to Legend.

 

Picture 42

Tutorial 1 - Figure 29 - Screenshot of the streamlines added to the in:Flux project for the Westerly ventilation simulation

 

The streamlines are truncated because they only go on for a certain period of time. The streamline will start at the seed point, then progress by a certain time step, at each point they move forward by whatever the local velocity is. To avoid the streamlines taking a long time to calculate in low velocity regions, they have to be stopped at some point. 250 is the defaulted number of time steps, this value can be changed via the properties panel and will be discussed more in Tutorial 6. Note that larger time steps will be less accurate.

 

The streamlines only go forward and back from the defined seed point – they are useful to give a general feel for the flow. If you are looking at the ventilation in a particular area, a contour or vector field should be used instead.