Peering through the flames: imaging techniques for reacting aluminum powders.

Combusting metals burn at high temperatures and emit high-intensity radiation in the visible spectrum, which can oversaturate regular imaging sensors and obscure the field of view. Filtering the luminescence can result in limited information and hinder thorough combustion characterization. A method for "seeing through the flames" of a highly luminescent aluminum powder reaction is presented using copper vapor laser (CVL) illumination, synchronized with a high-speed camera.

Derivation of governing equation describing time-dependent penetration length in channel flows driven by non-mechanical forces.

Several past attempts were made to describe the penetration length in microchannels as a function of time for electroosmotic or capillary flow. In all of these studies, a complex governing equation is derived by taking into account the inertial contributions along with other forces. The system being unsteady, this derivation requires the consideration of proper unsteady flow-profile inside the channel.

Effect of confining conduit on effective viscosity of dilute colloidal suspension.

In this article, we discuss the effect of the bounding cylinder on the rheology of a dilute suspension. We consider a colloidal solution of spherical particles flowing through a cylinder under creeping motion assumption. For transport of such particulate fluid, the increase in the viscous loss due to the existence of suspended particles can be described in terms of enhanced effective viscosity eta(eff) for the medium.

Effect of small particles on the near-wall dynamics of a large particle in a highly bidisperse colloidal solution.

We consider the hydrodynamic effect of small particles on the dynamics of a much larger particle moving normal to a planar wall in a highly bidisperse dilute colloidal suspension of spheres. The gap h(0) between the large particle and the wall is assumed to be comparable to the diameter 2a of the smaller particles so there is a length-scale separation between the gap width h(0) and the radius of the large particle b>>h(0). We use this length-scale separation to develop a new lubrication theory which takes into account the presence of the smaller particles in the space between the larger particle and the wall.

Cooperative motion of spheres arranged in periodic grids between two parallel walls.

In this article, we analyze the collective motion of a two-dimensional periodic array of spheres in a slit-pore confined by two parallel planar walls. We determine the friction coefficient of the spheres when all particles move with the same velocity along a particular direction and cooperate with each other in their motion. In order to solve this many-body problem, we use Stokesian dynamics algorithm and resolve multiparticle hydrodynamic interactions in wall-bounded geometry.