The convective-diffusion equation is the governing equation of many important transport phenomena in building physics. The paper deals in its first part with the general formulation of the convective-diffusion equation and with the numerical solution of this equation by means of the finite element method. The second part of the paper contains the analysis of one typical combined transport probl...

The jlux integral method is a procedure for constructing an explicit single-step forward-in-time conservative control-volume update of the unsteady multidimensional convection-d@usion equation. The convective-plusdifjiiveJlux at each face of a control-volume cell is estimated by integrating the transported variable and its face-normal derivative over the volume swept out by the convecting veloc...

In the case of dominating convection, standard Bubnov–Galerkin finite elements are known to deliver oscillating discrete solutions for the convection–diffusion equation. This paper demonstrates that increasing the polynomial degree (p-extension) limits these artificial numerical oscillations. This is contrary to a widespread notion that an increase of the polynomial degree destabilizes the disc...

In this paper we extend the Discrete Duality Finite Volume (DDFV) formulation to the steady convection-diffusion equation. The discrete gradients defined in DDFV are used to define a cellbased gradient for the control volumes of both the primal and dual meshes, in order to achieve a higher-order accurate numerical flux for the convection term. A priori analysis is carried out to show convergenc...

The paper reports on DNS and LES of plane channel flow at Reτ = 180 and compares these to a DNS with a higher order convection scheme. For LES different subgrid-scale models like the Smagorinsky, the Dynamic Smagorinsky and the Dynamic Mixed Model were used with the grid being locally refined in the near-wall region. The mixing of a passive scalar has been simulated with two convection schemes,...

A Petrov-Galerkin discretization is studied of an ultra-weak variational formulation of the convection-diffusion equation in mixed form. To arrive at an implementable method, the truly optimal test space has to be replaced by its projection onto a finite dimensional test search space. To prevent that this latter space has to be taken increasingly large for vanishing diffusion, a formulation is ...

Knowledge of the distribution in soil of radionuclides deposited following the release their to the environment is important for a reliable assessment of external dose and root uptake by plants. In order to predict the downward migration of radionuclide we should know the evolution in time the parameters of the model describing distribution of the radionuclide in soil layer. In this paper diffu...

A model for interpretation of extravascular indicator dilution experiments is proposed, in which the indicator is assumed to enter the blood-tissue exchange region through vascular sources, to equilibrate instantaneously and locally between blood and tissue at the capillary-cell level, and, while maintaining this local equilibration, to be transported to vascular sinks by simultaneous diffusion...

Of concern in the present theoretical investigation is the study of blood flow and convection-dominated diffusion processes in a model bifurcated artery under stenotic conditions. The geometry of the bifurcated arterial segment having constrictions in both the parent and its daughter arterial lumen frequently appearing in the diseased arteries causing malfunction of the cardiovascular system, i...