### ‎ Streamline Seed Points

in:Flux streamlines are based on two seed points. The line between the seed points is the basis for where the streamlines flow from. The streamlines can then go forward and backward from this seed point, as defined by the streamline direction

When first adding a streamline from the Add Items tab, the Auto-Seed checkbox is automatically selected. When this checkbox is selected, in:Flux automatically chosen seed points for you based on the domain and properties of the simulation. The coordinates will appear in gray text the Seed Line Point text boxes. The below example shows the Add Items panel of a streamline to be added to a project.

Tutorial 6 - Figure 88 - Add Items panel showing Auto-Seed being selected

Un-checking the Auto-Seed box will allow you to define your own seed points. If the seed point is downstream of an obstruction you can create some nice visuals of the re-circulation. We'll now open Tutorial 1's save file and define a streamline with a different seed point than what is automatically chosen by in:Flux.

1. Load Tutorial 1.ifx from the download tutorials zip file.

2. Turn off any visualizations that are already showing in the 3D window

3. From the Add Items tab, select Streamlines from the Select Item dropdown menu.

4. Set the Simulation as Westerly, 5m/s

5. From the Direction dropdown menu, choose Forward and Backward

6. Deselect the Auto-Seed checkbox and set a height of "4" as the Offset value.

7. Set the Relative to value as Domain and ensure the Auto-Range checkbox is selected.

8. With the Auto-Seed unchecked, we can now use the pick tool to define a new seed point. Under Seed Line Point 1 select the pick tool and choose a point near the north-eastern edge of the facility and then manually enter a value of 4 for the z-coordinate, or manually enter the coordinates of X: "17.9", Y: "42.24", and Z: "4".

Tutorial 6 - Figure 89 - Selection of Seed Line Point 1 to be at the north eastern edge of the CAD model. Clicking this point shown will require a value of "4" to be entered as the z coordinate

1. For the Seed Line Point 2 use the pick tool to select a point on the south-eastern edge of the facility and enter a z-coordinate of "4", ensure that your x-coordinate is similar to the one chosen in Step 8. You may also enter the coordinate to be X: "17.9", Y: "-6.55", and Z: "4" to match the figure below.

Tutorial 6 - Figure 90 - Selection of See Line Point 2, clicking the shown point will require entering a value of "4" in the z-coordinate

2. Click the Preview checkbox to ensure your screen is similar to the figure below.

Tutorial 6 - Figure 91 - Initial preview of streamlines with newly defined seed line

3. Notice how the southern edge of the facility does not have any streamlines present. This is because our lowest seed point value is -6.55 in the y-direction. No streamlines will appear beyond the coordinates of the seed points, even though the domain extends much further in the southern and northern directions. To resolve this, change the y-coordinate of Seed Line Point 2 to be "-25" and the y-coordinate of Seed Line Point 1 to be "50". Click Update next to the preview checkbox and your 3D window should appear as in the figure below.

Tutorial 6 - Figure 92 - Updated preview with new y-coordinate expanding the streamlines across the entire facility

4. Click Add Item.

This process can also be done for streamlines that have already been defined via the properties panel in the Streamlines Parameters section. Using Steps 8 and 9 you can select the arrow next to the coordinates and change the values for the x, y, and z coordinate or use the pick-tool to choose a point in the facility. Click the Confirm button to update the streamline with the new seed point.

Tutorial 6 - Figure 93 - Location for changing the Seed Points after a streamline visual has been defined via the properties panel of a selected streamline