Nowadays there are wide possibilities to perform numerical studies of turbulent natural convection flows on the base of 3D unsteady formulations [1]. Direct Numerical Simulation (DNS) is the most attractive and reliable approach for getting a detailed knowledge on convection [2, 3]. However, DNS applications are practically limited by the case of simplified geometry and/or the Rayleigh numbers ...

INTRODUCTION Recent randomised controlled trials suggest that on-line hemodiafiltration (OL-HDF) improves survival, provided that it reaches high convective volumes. However, there is scant information on the feasibility and the consequences of modifying convection volumes in clinics. METHODS Twelve stable dialysis patients were treated with high-flux 1.8 m2 polysulphone dialyzers and 4 level...

We investigate the stabilizing effect of convection in three-dimensional incompressible Euler and Navier-Stokes equations. The convection term is the main source of nonlinearity for these equations. It is often considered destabilizing although it conserves energy due to the incompressibility condition. In this paper, we show that the convection term together with the incompressibility conditio...

Miniaturized thermal flow sensors have opened the doors for a large variety of new applications due to their small size, high sensitivity and low power consumption. Theoretically, very small detection limits of air velocity of some micrometers per second are achievable. However, the superimposed free convection is the main obstacle which prevents reaching these expected limits. Furthermore, exp...

We present different ways, coming from Finite Volume or Mixed Finite Element frameworks, to discretize convection terms in Hybrid Finite Volume, Mimetic Finite Difference and Mixed Finite Volume methods for elliptic equations. We compare them through several numerical tests, and we present an application to a system modeling miscible flows in porous media.

A review of recent work and new developments are presented for the penalty-function, finite element formulation of incompressible viscous flows. Basic features of the penalty method are described in the context of the steady and unsteady Navier-Stokes equations. Galerkin and “upwind” treatments of convection terms are discussed. Numerical results indicate the versatility and effectiveness of th...

This article explains a simple way to demonstrate natural convection, such as from a lit candle, in the classroom using an overhead projector. The demonstration is based on the principle of schlieren imaging, commonly used to visualize variations in density for gas flows.

The recently introduced consistent lattice Boltzmann model with energy conservation [S. Ansumali and I. V. Karlin, Phys. Rev. Lett. 95, 260605 (2005)] is extended to the simulation of thermal flows on standard lattices. The two-dimensional thermal model on the standard square lattice with nine velocities is developed and validated in the thermal Couette and Rayleigh-Bénard natural convection pr...

A new artificial boundary condition for 2D subsonic flows governed by the compressible Navier–Stokes equations is derived. It is based on the hyperbolic part of the equations, according to the way of propagation of the characteristic waves. A reference flow as well as a convection velocity are used to properly discretize the terms corresponding to the entering waves. Numerical tests on various ...