The checkerboard model for the eddy-dispersion in laminar flows through porous media. Part I: Theory and velocity field properties.

The additivity assumption underlying Giddings' coupling model for the eddy-dispersion in laminar flows through heterogeneous media is critically analyzed and a potential solution for its non-additivity in the high velocity limit is presented. Whereas the unit cell in Giddings' model only consists of a single velocity bias step, the unit dispersion cell of the newly proposed model comprises two consecutive velocity bias steps. Consequently, the unit cell of this new model allows to account for the occurrence of an internal velocity bias rectification at high reduced velocities and is therefore additive in both the low and high velocity limit.

The checkerboard model for the Eddy-dispersion in Laminar flows through porous media. Part II: Application to ordered and disordered 2-D flow systems.

We report on a series of high-accuracy computational fluid dynamics band broadening simulations in three different 2-D flow systems: a 2-D pillar array and 2-D lumped packed bed geometries with different checkerboard velocity bias patterns. These media display a local maximum in the relationship between the eddy-dispersion plate height and the mobile phase velocity. The occurrence of such a dispersion maximum has not been reported before but appears to be a characteristic of regular chromatographic media with alternating velocity bias, at least in 2-D geometries.

A multiscale modelling study on the sense and nonsense of thermal conductivity enhancement of liquid chromatography packings and other potential solutions for viscous heating effects.

We report on a numerical study of the thermal conductivity and temperature distribution in analytical packed bed and monolithic HPLC columns to assess the feasibility of a number of potential solutions to the viscous heating problem that would normally impede high efficiency separations when moving to extreme operating pressures (e.g., 2500 bar).

Numerical and analytical investigation of the possibilities to enhance the thermal conductivity of core-shell particle packed beds.

We report on a numerical study of the thermal conductivity of core-shell particle packed bed columns. Covering a variety of packing structures and a broad range of mobile phase and porous zone conductivities, it was in all cases found that switching to particles with a highly conducting core (e.g.

The chromatographic performance of flow-through particles: A computational fluid dynamics study.

The performance of flow-through particles has been studied by computational fluid dynamics. Computational fluid dynamics simulations was used to calculate the flow behaviour around and inside the particles rather than estimate it. The obtained flow field has been used to accurately simulate plate heights generated by flow-through particles and compare them to standard fully porous particles.

The impact of flow distribution on column performance: a computational fluid dynamics study.

In this manuscript, the band broadening contribution of a generic flow distributor and collector has been calculated using computational fluid dynamics (CFD). The effects of distributor design and operating conditions on distributor performance have been studied. The non uniform flow fields in the distributor cause band deformation and an increase in volumetric band variance (σv(2)).

Theoretical study on the impact of slip flow on chromatographic performance.

We used numerical simulations to investigate the recent observation that slip flow chromatography can obtain reduced plate heights as low as 0.032. The simulations were carried out for a 2D pillar array and a 3D face centred cubic particle stacking.

Computational fluid dynamics study of the optimal design and operating conditions of the segmentation ring used in parallel segmented flow columns.

We report on a numerical study wherein we modeled the influence of the segmentation ring used in the recently introduced parallel segmented flow concept. The study reconfirms that the parallel segmented flow concept can indeed improve separation performance of radially heterogeneous beds. It was however also found that the segmentation ring in itself introduces significant flow disturbances.