We study the asymptotic behavior of the solutions of barotropic two-phase twopressure models, with pressure relaxation, drag force and external forces. Using Chapman-Enskog expansions close to the expected equilibrium, a drift-flux model with a Darcy type closure law is obtained. Besides, restricting this closure law to permanent flows (defined as steady flows in some Lagrangian frame), we can ...

Seepage into drifts in unsaturated tuff is an important issue for the long-term performance of the proposed nuclear waste repository at Yucca Mountain, Nevada. Drifts in which waste packages will be emplaced are subject to degradation in the form of rockfall from the drift ceiling, induced by stress-relief, seismic, or thermal effects. The objective of this study is to calculate seepage rates, ...

Using a drift flux representation for the two-phase flow, a new reduced order model has been developed to simulate density-wave oscillations (DWOs) in a heated channel. This model is then used to perform stability and semi-analytical bifurcation analysis, using the bifurcation code BIFDD, in which the stability boundary (SB) and the nature of Hopf bifurcation are determined in a suitable two-di...

The two-phase drift flux model is extensively used in multiphase flow applications. In this study, we focus on possible numerical schemes for solving the model. Due to complexity of primitive equations and empirical parameters, it challenging achieve stability scheme high resolution second order central scheme, central-upwind third fifth weighted essentially non-oscillatory (WENO) were successf...

We suggest a possible mechanism of efficient transport of the large-scale external magnetic flux inward through a turbulent accretion disk. The outward drift by turbulent diffusion which limits the effectiveness of this process is reduced if the external flux passes through the disk in concentrated patches. Angular momentum loss by a magnetocentrifugal wind from these patches of strong field ad...

We investigate three mechanisms that promote the loss of magnetic flux from an isolated neutron star. Ohmic decay produces a diffusion of the magnetic field with respect to the charged particles. It proceeds at a rate that is inversely proportional to the electric conductivity and independent of the magnetic field strength. Ohmic decay occurs in both the fluid core and solid crust of a neutron ...