Chandrasekhar–Kendall functions in astrophysical dynamos

AXEL BRANDENBURG^1,2

¹NORDITA, AlbaNova University Center, Roslagstullsbacken 23, SE 10691 Stockholm, Sweden

²Department of Astronomy, Stockholm University, SE 10691 Stockholm, Sweden

E-mail: brandenb@nordita.org

Abstract. Some of the contributions of Chandrasekhar to the field of magnetohydrodynamics are

highlighted. Particular emphasis is placed on the Chandrasekhar–Kendall functions that allow a

decomposition of a vector field into right- and left-handed contributions. Magnetic energy spectra

of both contributions are shown for a new set of helically forced simulations at resolutions higher

than what has been available so far. For a forcing function with positive helicity, these simulations

show a forward cascade of the right-handed contributions to the magnetic field and nonlocal inverse

transfer for the left-handed contributions. The speed of inverse transfer is shown to decrease with

increasing value of the magnetic Reynolds number.

Keywords. Magnetohydrodynamics; dynamos; turbulence.

PACS Nos 52.30.-q; 52.65.Kj; 47.11.+j; 47.27.Ak; 47.65.+a; 95.30.Qd