Karim Shariff

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A direct numerical simulation of a supersonic turbulent boundary layer has been performed. We take advantage of a technique developed by Spalart for incompressible ow. In this technique, it is assumed that the boundary layer grows so slowly in the stream-wise direction that the turbulence can be treated as approximately homogeneous in this direction. The(More)
We outline a scenario which traces a direct path from freely-floating nebula particles to the first 10-100km-sized bodies in the terrestrial planet region, producing planetesimals which have properties matching those of primitive meteorite parent bodies. We call this primary accretion. The scenario draws on elements of previous work, and introduces a new(More)
The method of contour dynamics, developed for two-dimensional vortex patches by Zabusky et al. [N.J. Zabusky, M.H. Hughes, K.V. Roberts, Contour dynamics for the Euler equations in two-dimensions, J. Comp. Phys. 30 (1979) 96–106] is extended to vortex rings in which the vorticity distribution varies linearly with normal distance from the symmetry axis. The(More)
A numerical method based on b-spline polynomials was developed to study incompressible flows in cylindrical geometries. A b-spline method has the advantages of possessing spectral accuracy and the flexibility of standard finite element methods. Using this method it was possible to ensure regularity of the solution near the origin, i.e. smoothness and(More)
The force exerted on a targeting sequence by the electrical potential across the inner mitochondrial membrane is calculated on the basis of continuum electrostatics. The force is found to vary from 3.0 pN to 2.2 pN (per unit elementary charge) as the radius of the inner membrane pore (assumed aqueous) is varied from 6.5 to 12 A, its measured range. In the(More)
Three-dimensional numerical simulations are used to investigate the possibility of diminishing the strength of trailing vortices. Direct numerical simulation is first used to reproduce results of recent laboratory experiments on the short-wave cooperative instability for two counter-rotating vortices. The effect of perturbing the vortices by internal and(More)
It is known that the stable and unstable manifolds of dynamical systems theory provide a powerful tool for understanding Lagrangian aspects of time-periodic flows. In this work we consider two time-periodic vortex ring flows. The first is a vortex ring with an elliptical core. The manifolds provide information about entrainment and detrainment of(More)