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Select the only face of the rectangle by shift-clicking on it and then click Apply.

Modify Edge Meshes

To change the number of divisions on the vertical edges from 5 to 10, choose:

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Make sure that the Remove old mesh box is checked under Options. This will make sure that the old edge meshes are erased before the new edge meshes are created.

Click Apply.

Remember that you can zoom in by holding down Ctrl, dragging a box across the area you want to zoom in on, and then releasing Ctrl. Do this now and make sure that the vertical edges have 10 divisions.

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Shift-click on the face in the Graphics Window to select it. Click Apply.

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Plot the skin friction coefficient as described in step 6. Compare the result with that obtained on the 100x5 mesh by loading it from cf.xy.

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The finer mesh provides a skin friction coefficient of 0.159 in the fully-developed region, which is much closer to the theoretical value of 0.16 than the corresponding coarser mesh value of 0.154. Save the data for this plot as cf2.xy.

Similarly, plot the velcoity profile at the outlet and compare with the coarser grid result in out.xy. The two results compare well with the greatest deviation occurring near the centerline. Save the data for this plot as out2.xy.

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If you repeat the calculation on a 100x20 mesh, you'll see that the results on the two finest meshes are grid-independent to a high level of accuracy. In the plots below, the white, red and green symbols correspond to the 100x20, 100x10 and 100x5 meshes, respectively.

Velocity along centerline:

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Skin Coefficient:

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Outlet Velocity:

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