Most theoretical investigations of particle acceleration during solar flares cannot be applied to observations for detailed study of the time evolution. We propose a phenomenological model for turbulence evolution and stochastic particle acceleration that links observations to the energy release and particle acceleration through two coefficients characterising particle interactions with turbule...

hisol isolator height [m] k turbulence kinetic energy [m2/s2] M Mach number p pressure [Pa] T temperature [°K] x axial (streamwise) coordinate [m] y vertical coordinate [m] yi mass-fraction of specie i y+ dimensionless vertical turbulence coordinate z lateral coordinate [m] φ equivalence ratio μ viscosity [N s/m2] ηc combustion efficiency ηm mixing efficiency ρ mass density [kg/m3] ω specific d...

We present a new parameterisation for shear-driven, stratified, turbulent mixing which is pertinent to climate models, in particular the shear-driven mixing in overflows and the Equatorial Undercurrent. Critically for climate applications this parameterisation is simple enough to be implemented implicitly, which allows the parameterisation to be used with timesteps that are long compared to bot...

[1] This study presents vertical profiles of turbulence parameters obtained in the upper 100 m of the northeastern Atlantic Ocean along a transect from tropical permanently stratified waters to subpolar seasonally stratified waters in July–August 2009. The focus is to fully characterize the vertical mixing along this transect for further studies related to phytoplankton and nutrient distributio...

The spectral model of Perry et al. (J. Fluid Mech., vol. 165, 1986, pp. 163–199) predicts that the integral length scale varies very slowly with distance to the wall in the intermediate layer. The only way for the integral length scale’s variation to be more realistic while keeping with the Townsend–Perry attached eddy spectrum is to add a new wavenumber range to the model at wavenumbers smalle...

Our turbulent lengthscale, velocity and diffusivity scalings are compared with data from other numerical, laboratory and field experiments. Comparison is made with reference to the turbulence intensity measure /νN. We showed that our turbulent lengthscale and velocity results are consistent with measurements from the experiments considered, and that the rms turbulent lengthscale Lt is independe...

The south-west of Western Australia has experienced significant land-cover change as well as a decline in rainfall. Given that the majority of precipitation results from frontal passages, the impact of land-cover change on the dynamics of cold fronts is explored using the Regional Atmospheric Modelling System version 6.0. Frontal simulations are evaluated against high resolution atmospheric sou...

The limitations of Hall MHD as a model for turbulence in weakly collisional plasmas are explored using quantitative comparisons to Vlasov-Maxwell kinetic theory over a wide range of parameter space. The validity of Hall MHD in the cold ion limit is shown, but spurious undamped wave modes exist in Hall MHD when the ion temperature is finite. It is argued that turbulence in the dissipation range ...

In free-surface flows, some flow instabilities may be observed, for example in pooled stepped spillways and hydraulic jumps. These instabilities may include some pulsations and oscillations. Most traditional two-phase flow analyses would yield some air-water turbulent flow results combining the contributions of the slow fluctuations and of the turbulent motion. Herein a new turbulence decomposi...

1 Abstract In this paper we discuss the dynamical features of intermittent fluctuations in homogeneous shear flow turbulence. In this flow the energy cascade is strongly modified by the production of turbulent kinetic energy related to the presence of vortical structures induced by the shear. By using direct numerical simulations, we show that the refined Kolmogorov similarity is broken and a n...