Dynamo effect in parity-invariant flow with large and moderate separation of scales Abstract It is shown that non-helical (more precisely, parity-invariant) flows capable of sustaining a large-scale dynamo by the negative magnetic eddy diffusivity effect are quite common. This conclusion is based on numerical examination of a large number of randomly selected flows. Few outliers with strongly n...

The dynamical equations of atmospheric flow are written using potential vorticity as the meridional coordinate and potential temperature as the vertical coordinate. Within this system, the atmosphere is divided into undulating tubes bounded by isentropic and constant potential vorticity surfaces, and, under adiabatic and frictionless conditions, the air moves through the tubes without penetrati...

Introduction: Phase-contrast velocity quantification is a valuable tool in cardiac magnetic resonance imaging. However, eddy-currents cause additional signal phases, which result in offsets in the velocity measurements. Even a relative small offset (>0.6 cm/s) can result in significant errors in clinical parameters [1]. Gatehouse et al. [2] showed that for a typical breath-hold flow protocol no...

Turbulence-resolving simulations of wall-bounded flows at high Reynolds numbers are presently unattainable due to the need to resolve fully the energy-carrying eddies in the near-wall region. Hybrid Reynolds-averaged Navier–Stokes/large-eddy simulations (RANS/LES), in which the nearwall eddies are modelled in a Reynolds-averaged sense, provide a cost-saving alternative. However previous attempt...

Ñ Large-Eddy Simulation of In-Cylinder Flows Ñ Advances in physical models, numerical methods, and computational power together have brought large-eddy simulation (LES) to the point where it warrants serious consideration for computing in-cylinder turbulent flows. This article includes: a discussion of LES and how it differs from Reynolds-averaged Navier Stokes (RANS) modeling; motivation for t...

We demonstrate, in the context of implicit-filtering large eddy simulations (LESs) of geostrophic turbulence, that while the attractor of a well-resolved statistically stationary turbulent flow can be reached in a coarsely resolved LES that is forced by the subgrid scale (SGS) terms diagnosed from the well-resolved computation, the attractor is generically unstable: the coarsely resolved LES sy...

A fully developed square channel flow with a Reynolds number of Re = 4410 (based on bulk velocity and duct width) has been calculated using Large Eddy Simulation (LES) technique with the Smagorinsky eddy viscosity model. Results for the Prandtl’s secondary motion which is turbulence-driven show good qualitative picture and are in good quantitative agreement with values from other authors. Diffe...

Eddying flow in the ocean develops as a result of baroclinic instability, and the environment in which the flow develops is vertically and horizontally inhomogeneous. A theory that takes into account the vertical inhomogeneities and predicts the magnitude and structure of the eddy potential vorticity flux for strongly baroclinically unstable mean shears is reviewed and extended to include the f...

Aims. To understand the fundamental physical processes important for the evolution of solar rotation and distribution of chemical species, we provide theoretical predictions for particle mixing and momentum transport in the stably stratified tachocline. Methods. By envisioning that turbulence is driven in the tachocline, we compute the amplitude of turbulent flow, turbulent particle diffusiviti...

The filtered fluid dynamic equations are discretized in space by a high-order spectral difference(SD) method coupled with large eddy simulation (LES) approach. The subgrid-scale stress tensor is modelled by the wall-adapting local eddy-viscosity model (WALE). We solve the unsteady equations by advancing in time using a second-order backward difference formula (BDF2). The nonlinear algebraic sys...