abstract: impeller trimming is a proper way to alter the performance of centrifugal pump with a constant speed so as to meet the demand on the specified flow rate and head in pumping systems. the affinity law accounting for the impeller trimming is the key relation to determine the pump performance with a trimmed impeller. there seems no experimental study dealing with such an affinity law for ...

We present the results of a combined theoretical and numerical investigation of the rim-driven retraction of flat fluid sheets in both planar and circular geometries. Particular attention is given to the influence of the fluid viscosity on the evolution of the sheet and its bounding rim. In both geometries, after a transient that depends on the sheet viscosity and geometry, the film edge eventu...

Potential flows u = ∇φ are solutions of the Navier–Stokes equations for viscous incompressible fluids for which the vorticity is identically zero. The viscous term μ∇u = μ∇∇φ vanishes, but the viscous contribution to the stress in an incompressible fluid (Stokes 1850) does not vanish in general. Here, we show how the viscosity of a viscous fluid in potential flow away from the boundary layers e...

Viscous GCG(generalized Chaplygin gas) cosmology is discussed, assuming that there is bulk viscosity in the linear barotropic fluid and GCG. The dynamical analysis indicates that the phase wg = −1 + √ 3γκτg/(γ − √ 3κτγ) is a dynamical attractor and the equation of state of GCG approaches it from either wg > −1 or wg < −1 depending on the choice of its initial cosmic density parameter and the ra...

We characterize the optimal dynamic price policy of a monopolist who faces “viscous” demand for its services. Demand is viscous if it adjusts relatively slowly to price changes. We show that with the optimal policy the monopolist stops short of achieving 100% market penetration, even when all of the consumers have the same long-run willingness to pay for the service. Furthermore, for certain pa...

Our experiments on viscous (Saffman-Taylor) fingering in Hele-Shaw channels reveal finger width fluctuations that were not observed in previous experiments, which had lower aspect ratios and higher capillary numbers Ca. These fluctuations intermittently narrow the finger from its expected width. The magnitude of these fluctuations is described by a power law, Ca(-0.64), which holds for all aspe...

The Eulerian description of an incompressible viscous fluid of constant density and temperature is concerned with the fluid velocity u(x, t) and pressure p(x, t) recorded at fixed positions x ∈ R, n = 3 as functions of time t. The solutions of the incompressible, inviscid Euler equations can be thought of as geodesic paths on an infinite dimensional group of transformations ([1]). This is done ...

Three inherent acidic chitinases were purified from yam aerial tuber by the application of quaternary ammonium ion detergent. For remoyal of the mucilage in the crude extract of aerial tuber, the effeets of various quaternary ammonium ion detergent were compared. Cetylpyridinium chloride effectiyely remoyed the mucilage and this method proyed to provide high recoyery of chitinase actiyity. Thre...

We carry out a comprehensive analysis of the behavior of the magnetorotational instability (MRI) in viscous, resistive plasmas. We find exact, non-linear solutions of the non-ideal magnetohydrodynamic (MHD) equations describing the local dynamics of an incompressible, differentially rotating background threaded by a vertical magnetic field when disturbances with wavenumbers perpendicular to the...