Backscatter is the process of energy transfer from small to large scales in turbulence; it is crucially important in the inverse energy cascades of two-dimensional and quasigeostrophic turbulence, where the net transfer of energy is from small to large scales. A numerical scheme for stochastic backscatter in the two-dimensional and quasigeostrophic inverse kinetic energy cascades is developed a...

Abstract The surface reactions of different energetic CHy molecules were studied using classical molecular dynamics. The sticking coefficient and the sputter yield of the different hydrocarbon species were studied for kinetic energies from 5 to 100 eV. Their dependence on the energy of the projectile and the angle of incidence are reported. Additionally, the results are compared to results from...

In a two-dimensional version of the modified Hasegawa-Wakatani (HW) model, which describes electrostatic resistive drift wave turbulence, the resistive coupling between vorticity and density does not act on the zonal components (ky = 0). It is therefore necessary to modify the HW model to treat the zonal components properly. The modified equations are solved numerically, and visualization and a...

In this paper, we present an alternative derivation of the entropy production in turbulent flows, based on a formal analogy with the kinetic theory of rarefied gas. This analogy allows for proving that the celebrated k − e model for turbulent flows is nothing more than a set of coupled BGK (Bhatnagar–Gross–Krook)-like equations with a proper forcing. This opens a novel perspective on this model...

Fully developed stationary premixed flames are obtained by DNS in an incoming homogeneous isotropic turbulent flow. Analysis based on the Favre-averaged transport equation of turbulent kinetic energy shows that pressure gradient term and pressure work term increase turbulent kinetic energy in the flame region, and these terms produce anisotropic turbulence. The counter-gradient diffusion domina...

Gibson scaling and related properties of flame-surface geometry in turbulent premixed combustion are demonstrated using a novel computational model, Deterministic Turbulent Mixing (DTM). In DTM, turbulent advection is represented by a sequence of maps applied to the computational domain. The structure of the mapping sequence incorporates pertinent scaling properties of the turbulent cascade. He...

Most of the ocean kinetic energy is contained in the large scale currents and the vigorous geostrophic eddy field, at horizontal scales of order 100 km. To achieve equilibrium the geostrophic currents must viscously dissipate their kinetic energy at much smaller scale. However, geostrophic turbulence is characterized by an inverse cascade of energy towards larger scale, and the pathways of ener...

The inverse transfer in two-dimensional turbulence governed by the surface quasigeostrophic (SQG) equation is studied. The nonlinear transfer of this system conserves the two quadratic quantities Ψ1 = 〈|(−∆) 1/4ψ|2〉/2 and Ψ2 = 〈|(−∆) 1/2ψ|2〉/2 (kinetic energy), where ψ is the streamfunction and 〈·〉 denotes a spatial average. In the limit of infinite domain, the kinetic energy density Ψ2 remains...

For the purpose of clarifying mechanism of local structure formations in magnetohydrodynamic (MHD) turbulence, energy transfers among various scales and positions of magnetic/kinetic energies in the course of roll-up processes of vortices are studied by direct numerical simulations (DNS) and orthonormalwavelet analysis. Initial shear layers are perturbed by three-dimensional random perturbation...