Simulations of convection in 3He-4He mixtures with a negative separation ratio in two-dimensional containers with realistic boundary conditions and moderately large aspect ratio reveal, at supercritical Rayleigh numbers, the existence of "convectons," i.e., localized states of stationary convection, separated by regions of no convection. The origin and properties of these states are described.

Geothermal energy resources such as geopressured geothermal brine (GGB) reservoirs and hot saline aquifers (HSA) can be potential clean energy resources provided the heat extraction from the subsurface is done in an economic and environmental friendly manner. In the proposed study, we are simulating the heat transfer processes around a downhole heat exchanger placed in a long lateral wellbore i...

This paper is devoted to comparing numerical schemes for a differential equation with convection and fourth-order diffusion. Our model equation is ut þ ðu uÞx 1⁄4 ðuuxxxÞx, which arises in the context of thin film flow. First we employ implicit schemes and treat both convection and diffusion terms implicitly. Then the convection terms are treated with wellknown explicit schemes, namely Godunov,...

Numerical simulation of tritium permeation from breeding zones to the coolant in the helium cooled pebble-bed blanket is performed in this paper. 2D and 3D convection–diffusion models are developed to account for the effects of purge stream convection. Incompressible transient Brinkman model with variable permeability is used in flow calculation, and transient diffusion and convection equations...

Drying kinetics of sour cheery is investigated in solar dryer with forced convection and under open Sun with natural convection. Drying data were fitted to different mathematical models, whose performance was investigated by comparing coefficient (R), reduced chi-square (Ç) and root mean square error (RMSE) between the observed and predicted moisture ratios. Among these models, drying model dev...

In this paper, the effect of a simple convection scheme on the zonally averaged tropical general circulation is examined within an idealized moist GCM to obtain broad classifications of the influence of convection on the Tropics. This is accomplished with a simplified convection scheme in the style of Betts and Miller. The scheme is utilized in a moist GCM with simplified physical parameterizat...

A b s t r a c t : Hydrodynamic simulations of the solar convection zone can be used to model the generation of differential rotation and magnetic fields, and to determine mean-field transport coefficients that are needed in mean-field models. The importance of the overshoot layer beneath the solar convection zone is discussed: it is the place where the magnetic field accumulates, although most ...

In this paper we consider various blends of implicit and explicit time integration schemes based on the well-known BDF2 method, applied to convection-diffusion problems with dominating convection. A fully implicit treatment of convection terms is often not very efficient. We shall deal with schemes that are implicit in the convection terms only locally in space, without introducing the internal...

We briefly review the crucial effect that convection plays in the evolution, interior and atmospheric physics of brown dwarfs. In particular, we discuss: (1) the role of convection in the interior structure and evolution of brown dwarfs (BDs); (2) the importance of convection in the atmospheres of ultra-cool objects, at both high and low gravities (i.e., in both young and old BDs); and (3) the ...