Deformation and breakup of a viscous drop in a Bingham liquid is investigated numerically with a volume-of-fluid scheme. Initially, a spherical drop is placed between two moving parallel plates. For our parameters, the matrix liquid has yielded. The competing effects driving the motion are the shear and interfacial tension. When interfacial tension effects dominate, the drop evolves to a steady...

an experimental study was carried out on the wake of a cylinder on the back of which a plate is installed parallel to the fluid flow, with different terminal angles, where the reynolds number is 50000. at the end of the plate, blades with the height of 0.25 equal to the cylinder diameter and with 45, 90 and 135 degrees angle from the horizon, are installed where the cylinder diameter is equal t...

this paper presents efflux time experiments performed in the absence and presence of aqueous solutions of drag reducing agents (dras) when a liquid is emptied from a large open cylindrical storage tank through an exit piping system. the drag reducing agents studied are dodecyl benzene sulfonate anionic surfactant and a mixed solution of surfactant and sodium chloride counter ion. the variables ...

We report experimental data and theoretical analysis of Coulomb drag between two closely positioned graphene monolayers in a weak magnetic field. Close enough to the neutrality point, the coexistence of electrons and holes in each layer leads to a dramatic increase of the drag resistivity. Away from charge neutrality, we observe nonzero Hall drag. The observed phenomena are explained by decoupl...

The drag force on aggregates and partially sintered agglomerates is assessed using the lattice Boltzmann method (LBM) and accelerated Stokesian dynamics (ASD). Both methods have been compared in terms of accuracy and computational effort. It is shown that they give comparable results if all numerical parameters are controlled carefully. LBM requires a much higher computational effort, however, ...

The effects of breaking waves on near-surface wind turbulence and drag coefficient are investigated using large-eddy simulation. The impact of intermittent and transient wave breaking events (over a range of scales) is modeled as localized form drag, which generates airflow separation bubbles downstream. The simulations are performed for very young sea conditions under high winds, comparable to...

A critical analysis of the numerous works on dolphin swimming shows that several uncertainties led to incorrect conclusions concerning the estimates of dolphin drag coefficients. Original results on dolphin kinematics and hydrodynamics indicate the existence of a drag-reduction mechanism, caused by the formation of a negative pressure gradient along the body during active swimming. The mathemat...

We describe here the first example of the synthesis of 4-arm star poly(acrylic acid) for use as a water-soluble drag reducing agent, by applying Cu(0)-mediated polymerization technique. High molecular weight 4-arm star poly(tert-butyl acrylate) (Mn = 3.0-9.0 x 10 5 g mol -1 ) was first synthesized using 4,4’-oxybis(3,3-bis(2-bromopropionate)butane as an initiator and a simple Cu(0)/TREN catalys...