Astrophysical significance of the anisotropic kinetic alpha effect

The generation of large scale flows by the anisotropic kinetic alpha (AKA) effect is investigated in simulations with a suitable time-dependent space- and time-periodic anisotropic forcing lacking parity invariance. The forci ng pattern moves relative to the fluid, which leads to a breaking of the Ga lilean invariance as required for the AKA effect to exist. The AKA effect i s found to produce a clear large scale ow pattern when the Reynolds number, R, is small as only a few modes are excited in linear theory. In this case the non-vanishing components of the AKA tensor are dynamically independent of the Reynolds number. For larger values of R, many more modes are excite d and the components of the AKA tensor are found to decrease rapidly with i ncreasing value of R. However, once there is a magnetic field (imposed and of sufficient strength, or dynamo-generated and saturated) the field begins to suppress the AKA effect, regardless of the value of R. It is argued tha t the AKA effect is unlikely to be astrophysically significant unless the m agnetic field is weak and R is small.