We measure the turbulent diffusion coefficient of dust grains embedded in magnetorotational turbulence in a protoplanetary disc directly from numerical simulations and compare it to the turbulent viscosity of the flow. The simulations are done in a local coordinate frame comoving with the gas in Keplerian rotation. Periodic boundary conditions are used in all directions, and vertical gravity is...

We examine the effects of density stratification on magnetohydrodynamic turbulence driven by the magnetorotational instability in local simulations that adopt the shearing box approximation. Our primary result is that, even in the absence of explicit dissipation, the addition of vertical gravity leads to convergence in the turbulent energy densities and stresses as the resolution increases, con...

The motion of an incompressible fluid confined to a shallow basin with a slightly varying bottom topography is considered. Coriolis force, surface wind and pressure stresses, together with bottom and lateral friction stresses are taken into account. We introduce appropriate scalings into a three-dimensional anisotropic eddy viscosity model; after averaging on the vertical direction and consider...

introduction: many studies have been performed to evaluate the stress distribution around endodontic posts; those which compared posts composed of different materials are rare. the aim of this study was to compare stresses induced in dentin by three structurally different posts using photoelasticity method. materials and methods: nine blocks of psm-5 photoelastic material with 45×45×10 mm dimen...

the unsteady free convection flow between two long vertical parallel plates withvariable temperature and mass diffusion in the presence of the thermal radiation hasbeen presented. the governing dimensionless coupled linear partial differentialequations on the flow are solved by using the laplace transform technique. theexact solutions have been obtained for the fluid velocity, temperature and t...

The purpose of this paper is to understand the combined effect of thermal and mechanical plastic deformation on residual stresses in ground components. The interactions between a grinding wheel and a workpiece, including both thermal and mechanical interaction, are simulated by triangular surface loads moving with the table speed of grinding. Cooling is modelled by a uniform convection over the...

PURPOSE Three-dimensional finite element analysis was conducted to evaluate and compare the stress distribution in the abutment and retention screw of implant-supported single crowns with platform switching and with a conventional platform under vertical and oblique loading. MATERIALS AND METHODS Two finite element models were created simulating an osseointegrated implant (4 × 10 mm, platform...

A two-dimensional finite element model of a mandibular quadrant was used to examine differences in magnitude of the principal stresses from the placement of three- and four-unit bridges. The area of interest spanned the first premolar to the second molar. Loading conditions were (i) vertical and distributed and (ii) 30 degrees to the vertical and concentrated. The principal stresses were calcul...

Offshore wind turbine (OWT) foundations are subjected to a combination of cyclic and dynamic loading arising from wind, wave, rotor and blade shadowing. Under cyclic loading, most soils change their characteristics including stiffness, which may cause the system natural frequency to approach the loading frequency and lead to unplanned resonance and system damage or even collapse. To investigate...