Turbulence and mixing in a nearbottom convectively driven flow are examined by numerical simulations of a model problem: a statically unstable disturbance at a slope with inclination $\unicode[STIX]{x1D6FD}$ in a stable background with buoyancy frequency $N$ . The influence of slope angle and initial disturbance amplitude are quantified in a parametric study. The flow evolution involves energy exchange between four energy reservoirs, namely the mean and turbulent components of kinetic energy (KE) and available potential energy (APE). In contrast to the zeroslope case where the mean flow is negligible, the presence of a slope leads to a current that oscillatesmore »
Magnetoimmutable turbulence in weakly collisional plasmas
We propose that pressure anisotropy causes weakly collisional turbulent plasmas to selforganize so as to resist changes in magneticfield strength. We term this effect ‘magnetoimmutability’ by analogy with incompressibility (resistance to changes in pressure). The effect is important when the pressure anisotropy becomes comparable to the magnetic pressure, suggesting that in collisionless, weakly magnetized (high $\unicode[STIX]{x1D6FD}$ ) plasmas its dynamical relevance is similar to that of incompressibility. Simulations of magnetized turbulence using the weakly collisional Braginskii model show that magnetoimmutable turbulence is surprisingly similar, in most statistical measures, to critically balanced magnetohydrodynamic turbulence. However, in order to minimize magneticfield variation, the flow direction becomes more constrained than in magnetohydrodynamics, and the turbulence is more strongly dominated by magnetic energy (a nonzero ‘residual energy’). These effects represent key differences between pressureanisotropic and fluid turbulence, and should be observable in the $\unicode[STIX]{x1D6FD}\gtrsim 1$ turbulent solar wind.
 Award ID(s):
 1804048
 Publication Date:
 NSFPAR ID:
 10204598
 Journal Name:
 Journal of Plasma Physics
 Volume:
 85
 Issue:
 1
 ISSN:
 00223778
 Sponsoring Org:
 National Science Foundation
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