The 1-1/2 fluid is a conformal solution in which one species has a size parameter ~diameter! of zero. This ‘‘point-particle’’ species nevertheless interacts with the other component of the mixture, as the collision diameter of a point particle and a finite particle is nonzero. A great simplifying feature of this model mixture is that the point particles do not interact with each other. For hard...

We investigate two distinct universality classes for probe particles that move stochastically in a one-dimensional driven system. If the random force that drives the probe particles is fully generated by the current fluctuations of the driven fluid, such as when the probe particles are embedded in a ring, they inherit the dynamical exponent of the fluid, which generically is z = 3/2. On the oth...

The vertical motion of particles, drops and organisms through density stratified fluids is ubiquitously found in oceans and lakes. Settling dynamics of marine snow particles, rising motion of drops during oil spills, formation of phytoplankton blooms, and diel vertical migration of organisms are just a few of these examples. Transport properties in these examples are modified when the density o...

Electric fields generate transverse flows near electrodes that sweep colloidal particles into densely packed assemblies. We interpret this behavior in terms of electrohydrodynamic motion stemming from distortions of the field by the particles that alter the body force distribution in the electrode charge polarization layer. A scaling analysis shows how the action of the applied electric field g...

The fate of aerosols in open flows is relevant in a variety of physical contexts. Previous results are consistent with the assumption that such finite-size particles always escape in open chaotic advection. Here we show that a different behavior is possible. We analyze the dynamics of aerosols both in the absence and presence of gravitational effects, and both when the dynamics of the fluid par...

The orbits of fluid particles in two dimensions effectively act as topological obstacles to material lines. A spacetime plot of the orbits of such particles can be regarded as a braid whose properties reflect the underlying dynamics. For a chaotic flow, the braid generated by the motion of three or more fluid particles is computed. A "braiding exponent" is then defined to characterize the compl...

Our first paper' presented the theory of a method for separating a mixture of particles according to mass. The second2 reported the results obtained with a gravitational device in the effective mass range 10-14 to 10-'3 gm. Here we describe experiments designed to test the feasibility of separating particles with effective masses as small as 10-18 gm. In the gravity experiments particles are ad...

Simulating fluid scenes in 3DGIS is of great value in both theoretical research and practical applications. To achieve this goal, we present an algorithm for simulation of fluid scenes based on smoothed particle hydrodynamics. A 3D spatial grid partition algorithm is proposed to increase the speed for searching neighboring particles. We also propose a real-time interactive algorithm about parti...

Abstract The surprising result of a recent experiment in turbulent helium II is that micron–size tracer particles move with about half the speed of the imposed normal fluid. We develop a theory of the interaction of small spheres with quantized vortices and predict that the particles slip velocity (resulting from the balance of buoyancy and Stokes drag forces) must be corrected by an amount whi...

We provide a brief overview of some Monte Carlo methods which have been used to simulate systems with a turbulent fluid component. We discuss two main classes of simulation approaches: an “Eulerian” class which is based on a random velocity field model defined on a fixed coordinate system, and a “Lagrangian” class in which the motion of fluid particles and immersed particles are instead stochas...