This paper presents results of several large-eddy simulations LES of turbulent flow in an open channel through staggered arrays of rigid, emergent cylinders, which can be regarded as idealized vegetation. In this study, two cylinder Reynolds numbers, RD =1,340 and RD=500, and three vegetation densities are considered. The LES of the lowest density and at RD=1,340 corresponds to a recently compl...

We consider directed graphs with an upward planar drawing on the plane, the sphere, the standing and the rolling cylinders. In general, the drawings allow complex curves for the edges with many zig-zags and windings around the cylinder and the sphere. The drawings are simplified to polyline drawings with geodesics as straight segments and vertices and bends at grid points. On the standing cylin...

Two aspects of vorticity associated with cold pools are addressed. First, tilting of horizontal vortex tubes by the updraft at a gust front has been proposed as a means of getting near-ground rotation and hence a tornado. Theory and a numerical simulation are used to show that this mechanism will not work because warm air parcels approaching the gust front decelerate in strong adverse pressure ...

We describe a number of different phenomena seen in the free-surface flow inside a partially filled circular cylinder which is rotated about its horizontal axis of symmetry. At low angular velocities the flow settles into a steady two-dimensional flow with a front where the coating film coalesces with the pool at the bottom of the cylinder. This mode becomes unstable at higher angular velocitie...

Regarding the vibrating seeds box of magnetic cylinder seeder as the research subject and making simulation and analysis for the motion law of seeds which supplied by seed box base on DEM (Discrete Element Method). Researching the mechanism of the seed supply and analyzing the condition of seed supply by the vibration of seed box, when the frequency change from 10Hz to 50Hz and horizontal and v...

We formulate the problem of coupled heat and mass transfer by natural convection from a horizontal cylinder embedded in a uniform porous medium in the presence of an external magnetic Ž eld and internal heat generation or absorption effects. The cylinder surface is maintained at a constant temperature and a constant concentration and is permeable to allow for possible  uid wall suction or blow...

Centripetal instabilities in two flows involving time-dependent Rayleigh layers on a rotating circular cylinder are examined. In one case we consider the stability of the flow induced in an infinite expanse of quiescent fluid when the cylinder is impulsively given a constant angular velocity; in the other problem the angular velocity increases as the square root of time so that the undisturbed ...