Cascades of enstrophy and helicity in turbulence without vortex stretching

International audienceWe consider three-dimensional turbulence from which vortex stretching is removed. Using direct numerical simulations, we show that in this system a dual cascade is observed, consisting of a forward enstrophy cascade and an inverse helicity cascade. In the inverse cascade range the energy spectrum scaling is proportional to k −7/3 , with k being the wave number. In the forward cascade range the spectrum is proportional to k −3 with a logarithmic correction