Lagrangian acceleration and its Eulerian decompositions in fully developed turbulence

We study the properties of various Eulerian contributions to fluid particle acceleration by using well-resolved direct numerical simulations of isotropic turbulence, with the Taylor-scale Reynolds number Rλ in the range 140-1300. The variance of convective acceleration, when normalized by Kolmogorov scales, increases as Rλ, consistent with simple theoretical arguments, but differing from classical Kolmogorov's phenomenology, as well as Lagrangian extension of Eulerian multifractal models. The scaling of the local acceleration is also linear in Rλ to the leading order, but more complex in detail. The strong cancellation between the local and convective acceleration - faithful to the random sweeping hypothesis - results in the variance of the Lagrangian acceleration increasing only as Rλ0.25, as recently shown by Buaria and Sreenivasan [Phys. Rev. Lett. 128, 234502 (2022)0031-900710.1103/PhysRevLett.128.234502]. The acceleration variance is dominated by the irrotational pressure gradient contribution, whose variance essentially follows the Rλ0.25 scaling; the solenoidal viscous contributions are comparatively small and follow Rλ0.13, which is the only acceleration component consistent with multifractal prediction.