Can shear and magnetic buoyancy can drive nonlinear dynamo activity?
It is believed that the sun is able to maintain its magnetic fields because of a combination of magnetic field shear stretching (the omega effect) and magnetic field twisting (the alpha effect), which together drive the 11-year sunspot cycle. When we saw these twisting events in our shear simulations, we wondered if these might allow our simulations to maintain a field in a stretch-twist dynamo process. So we tried a new set of simulations: We set the weak initial field so that it was positive in the top half of the domain, and negative in the bottom half. In this way, if there was no dynamo activity, all magnetic fields would diffuse away over time. We also changed the shear so that rather than than having a cosine y profile, instead it was more of a sawtooth function of y, so that it would create one strong magnetic structure in the center (with Bx x > 0). We found that if magnetic forces were weak, then they were insufficient to create enough buoyant activity to trigger a Kelvin-Hel
