In marked contrast with the role of differential rotation in the magnetic induction,
effect of inhomogeneous global flow in turbulence has been disregarded in the dynamo studies.
This effect enters the turbulent electromotive force through turbulent cross helicity
(velocity--magnetic-field correlation). A new simple dynamo model with the cross helicity for
stellar activity cycle is proposed. In the model, the equation of the turbulent cross helicity
is simultaneously solved with the equations of the mean magnetic fields. It is shown through
the eigenvalue analysis of the present system of equations that the spatiotemporal evolution
of the turbulent cross helicity is the cause of polarity reversal of the mean magnetic fields.
References:
N. Yokoi, “Cross helicity and related dynamo,” Geophys. Astrophys. Fluid Dyn. 107, 114-184 (2013).
http://www.tandfonline.com/doi/abs/10.1080/03091929.2012.754022
N. Yokoi, D. Schmitt, V. Pipin, and F. Hamba, “A new simple dynamo model for stellar activity cycle,”