If the binding energy of the pulsar’s surface is not so high (the case of a neutron star), both the negative and positive charges will flow out freely from the surface of the star. The annular free flow model for γ-ray emission of pulsars is suggested in this paper. It is emphasized that: (1). Two kinds of acceleration regions (annular and core) need to be taken into account. The annular accele...

The present work is concerned with a numerical study of the performance of a conical annular centrifugal contractor through the analysis of the flow properties when the apex angle is changed for different imposed axial flows. The calculations revealed the advantage of using conical annular centrifugal contractors compared to the cylindrical annular centrifuges. The study is conducted by a compa...

With the increasing demand for heavy oil, core annular flow (CAF) is an economical method to transport and many researchers have explored energy-saving aspects of CAF method. This paper presents a review energy saving factors affecting saving. Among them, mainly concerns changes in pressure drop drag reduction efficiency; concern problem stability, issue restarting pipeline system, impact nozzl...

A numerical study, using the volume-of-fluid method (VOF), has been made of core-annular flow in a curved pipe. We investigated two cases: core-annular flow in a 90◦ bend and in a 180◦ return bend. To verify our numerical method we first compared our results for a singlephase flow in a 90◦ bend with numerical results and experimental data given in the literature. The agreement was good. Thereaf...

a mathematical analysis has been carried out for the axial flow of a bingham plastic fluid, in the concentric cylinder viscometer which consists of a cylindrical sample holder (the cup) and a cylindrical spindle (the bob) coaxial with the cup. the fluid to be tested flows through the annular gap of the cup and the bob system, sheared by the rotation of the inner cylinder, while the outer cylind...

A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity annular liquid layer through a horizontal pipe. Special attention is paid to the question how the buoyancy force on the core, caused by a possible density difference between the core and the annular layer, is counterbalanced. From earlier studies it is known tha...

Annular patterns with a high degree of zonal symmetry play a prominent role in the natural variability of the atmospheric circulation and its response to external forcing. But despite their apparent importance for understanding climate variability, the processes that give rise to their marked zonally symmetric components remain largely unclear. Here the authors use simple stochastic models in c...