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Jet/Wind Bunny Ears

Problem

When driving a wind or a small aperture (4-8 zones) jet on to the grid the flow develops the following bizarre features which look like bunny ears:

See Attached Images (Speed): sw10-exp-554.png, jet4-1.png

Solution

These features are carbuncles caused when the flow is close to being on axis but not quite. The solution is to set ViscCD to 2. This turns on the H-viscosity which will add a small bit of viscosity to the flow when the flow is close to being on axis. The change cleans up the flow as shown below:

See Attached Images (Speed): sw10-exp-VCD2-553.png, jet4-1-VCD1.png

More Info

For more information on how this problem was diagnosed see:

​http://www.astro.umn.edu/~pedmon/wjbunny.html