An investigation of a model of turbulence generation in the wall region of a turbulent boundary layer is made through direct numerical simulations. The model is based on the instability of a streak. First, a laminar boundary layer disturbed by a continuous blowing through a slot is simulated in order to reproduce and further investigate the results reported from the experiments of Acarlar & Smi...

The aim of this note is to investigate f -vectors of simplicial balls, especially the relations between interior and boundary faces. For a simplicial ball B we denote by fi(B) the number of i-dimensional faces. The boundary ∂B of B is a simplicial sphere with face numbers fi(∂B). We also define fi(int B) := fi(B) − fi(∂B) although the interior int B of B is not a polyhedral complex. For simplic...

The volume contained within any closed, simple, piece-wise smooth boundary can be determined by integrating over the boundary a function whose only parameters are the principal boundary curvatures and the distance to the medial manifold. The method is an extension of the common concept of mining rights, by which the interior of the earth is parceled out to patches of real estate on the surface....

The volume contained within any closed, simple, piece-wise smooth boundary can be determined by integrating over the boundary a function whose only parameters are the principal boundary curvatures and the distance to the medial manifold. The method is an extension of the common concept of mining rights, by which the interior of the earth is parceled out to patches of real estate on the surface....

A polygon P is x-monotone if any line orthogonal to the x-axis has a simply connected intersection with P . A set G of points inside P or on the boundary of P is said to guard the polygon if every point inside P or on the boundary of P is seen by a point in G. An interior guard can lie anywhere inside or on the boundary of the polygon. Using a reduction fromMonotone 3SAT, we prove that interior...

This paper formulates a model of mixing in a stratified and turbulent fluid. The model uses the horizontally averaged vertical buoyancy gradient and the density of turbulent kinetic energy as variables. Heuristic ‘mixing-length’ arguments lead to a coupled set of parabolic differential equations. A particular form of mechanical forcing is proposed; for certain parameter values the relationship ...