Geometry Sequence Instructions
Below you find the instructions on how to set up the geometry manually if the geometry has not been imported.
Parameters
1
In the Home toolbar click Parameters and select Parameter 1 .
Note: On Linux and Mac, the Home toolbar refers to the specific set of controls near the top of the Desktop.
2
Go to the Settings window for Parameters. Under Parameters click Load from File .
Browse to the application library folder (Acoustics_Module\Automotive) and double-click the file absorptive_muffler_geom_sequence_parameters.txt.
Geometry
1
In the Model Builder under Component 1, click Geometry 1 .
2
Go to the Settings window for Geometry. Under Units from the Length unit list, choose mm.
Work Plane 1
1
In the Geometry toolbar click Work Plane .
2
Go to the Settings window for Work Plane. Under Plane Definition, from the Plane list choose yz-plane.
Rectangle 1
1
Right-click Plane Geometry  and add a Rectangle .
2
Go to the Settings window for Rectangle. Under Size in the:
-
Width text field, enter W.
-
Height text field, enter H.
3
Locate the Position section. From the Base list, choose Center.
Fillet 1
1
On the Work plane toolbar click Fillet .
2
On the object r1, select Points 1,2,3,4 only.
Note: There are many ways to select geometric entities. When you know the points to add, such as in this exercise, you can click the Paste Selection button  and enter the information in the Selection text field. In this example for the Fillet 1 node, enter 1,2,3, 4 in the Paste Selection window. For more information about selecting geometric entities in the Graphics window, see the COMSOL Multiphysics Reference Manual.
3
Go to the Settings window for Fillet. Under Radius in the Radius text field, enter H/2.
Rectangle 2
1
Right-click Plane Geometry and choose Rectangle .
2
Go to the Settings window for Rectangle. Under Size in the:
-
Width text field, enter W-2*D.
-
Height text field, enter H-2*D.
3
Locate the Position section. From the Base list, choose Center.
Fillet 2
1
On the Work plane toolbar, click Fillet .
2
On the object r2, select Points 1,2,3,4 only.
3
Go to the Settings window for Fillet. Under Radius in the Radius text field, enter (H-2*D)/2.
4
Click the Build All button in the Settings window or Home toolbar.
The geometry in the Graphics window and the node sequence under Work Plane 1 should match these figures at this point:
Extrude 1
1
On the Work plane toolbar, click Close .
2
In the Geometry toolbar click Extrude .
3
Go to the Settings window for Extrude. Under Distances from Plane in the table under Distances (mm), enter L in the column (replace the default).
Cylinder 1
1
In the Geometry toolbar click Cylinder .
2
Go to the Settings window for Cylinder. Under Size and Shape in the:
-
Radius text field, enter R_io.
-
Height text field, enter L_io.
3
Under Position in the x text field, enter -L_io.
4
Under Position in the y text field, enter d_center.
5
Under Axis:
-
From the Axis type list, choose Cartesian.
-
In the x text field, enter 1.
-
In the z text field, enter 0.
Cylinder 2
1
In the Geometry toolbar click Cylinder .
2
Go to the Settings window for Cylinder. Under Size and Shape in the:
-
Radius text field, enter R_io.
-
Height text field, enter L_io.
3
Under Position in the x text field, enter L.
4
Under Position in the y text field, enter -d_center.
5
Under Axis:
-
From the Axis type list, choose Cartesian.
-
In the x text field, enter 1.
-
In the z text field, enter 0.
6
Click the Build All button In the Home toolbar. Click the Zoom Extents button  in the Graphics toolbar.
The node sequence in the Model Builder should match the figure.
The finished geometry is shown in the figure below, the axis dimensions are in mm, as selected, and the system of coordinates is also shown.