Results
Three plots are automatically created, one slice plot for the velocity, one pressure surface plot on the walls and one boundary plot of the wall lift-off in viscous units for the wall functions. The last one is important since it gives an indication of how well resolved the flow is at the walls. See Theory for the Turbulent Flow Interfaces in the CFD Module User’s Guide for further details on wall functions.
The following steps reproduce Figure 11.
Velocity (spf)
1
In the Model Builder window, under Results click Velocity (spf) .
2
In the Settings window for 3D Plot Group, click to expand the Selection section.
3
From the Geometric entity level list, choose Boundary.
4
Select Boundaries 1, 3 and 28, corresponding to the inlet, symmetry plane and outlet boundaries.
5
In the Model Builder window, expand the Velocity (spf)  node.
6
Right-click Multislice  and choose Delete. Click Delete to confirm.
7
In the Velocity (spf) toolbar click Surface  to generate a surface plot of the velocity magnitude.
8
In the Velocity (spf) toolbar click Arrow Surface .
9
In the Settings window for Arrow Surface, locate the Arrow Positioning section. In the Number of arrows text field, type 300.
10
In the Settings window for Arrow Surface, locate the Coloring and Style section.
-
From the Arrow length list, choose Logarithmic.
-
Select the Scale factor checkbox. In the associated text field, type 1.4.
-
From the Color list, choose White.
11
In the Velocity (spf) toolbar click Surface .
12
In the Settings window for Surface, locate the Expression section and type 1 in the Expression text field.
13
Locate the Coloring and Style section.
-
From the Coloring list, choose Uniform.
-
From the Color list, choose Gray.
14
Right-click Surface 2 and choose Selection .
15
In the Settings window for Selection, locate the Selection section.
16
From the Selection list, choose Box Selection: Walls.
17
In the Model Builder click Velocity (spf) .
18
In the Settings window for 3D Plot Group, click to expand the Title section.
-
From the Title type list, choose Manual.
-
In the Title text area, type Velocity field.
19
Click the Plot button .
Also reproduce Figure 12 as follows.
1
In the Model Builder under Velocity (spf), right-click Surface 2 and choose Copy .
3D Plot Group 4
1
In the Home toolbar click Add Plot Group  and choose 3D Plot Group .
2
In the Model Builder right-click 3D Plot Group 4  and choose Paste Surface .
3
In the 3D Plot Group 4 toolbar click Streamline .
4
In the Settings window for Streamline, go to the Selection section and select Boundary 1, which is the inlet. The streamlines now start at this boundary.
5
In the Settings window for Streamline:
-
Locate the Streamline Positioning section. In the Number text field, type 45.
-
Locate the Coloring and Style section. Find the Line Style subsection. From the Type list, choose Ribbon.
-
In the Width expression text field, type spf.nuT*1[s/m]. The width of the streamlines is set to the local value of the turbulent viscosity and the factor 1[s/m] is used to get the right dimension.
-
Select the Width scale factor checkbox. In the associated text field, type 100.
6
Right-click Results > 3D Plot Group 4 > Streamline 1  and choose Color Expression .
7
In the Settings window for Color Expression, click to expand the Range section.
-
Select the Manual color range checkbox.
-
In the Minimum text field, type 0.
-
In the Maximum text field, type 0.1.
8
In the Model Builder click 3D Plot Group 4 .
9
In the Settings window for 3D Plot Group, locate the Title section.
-
From the Title type list, choose Manual.
-
In the Title text area, type Streamlines colored by velocity, width proportional to turbulent viscosity.
10
In the 3D Plot Group 4 toolbar click Plot .
11
In the Label text field, type Streamlines.
This concludes the introduction to the COMSOL CFD Module.