Analysis of Hemodynamic Fluid Phase Mass Transport in a Separated Flow Region

Abstract

The mass transfer behavior in the recirculation region downstream of an axisymmetric sudden expansion was examined. The Reynolds number, 500, and Schmidt number, 3200, were selected to model the mass transfer of molecules, such as ADP, in the arterial system. In a first step the transient mass transport applying zero diffusive flux at the wall was analyzed using experiments and two computational codes. The two codes were FLUENT, a commercially available finite volume method, and FTSP, a finite element code developed at Graz University of Technology. The comparison of the transient wall concentration values determined by the three methods was excellent and provides a measure of confidence for computational mass transfer calculations in convection dominated, separated flows. In a second step the effect of the flow separation on the stationary mass transport applying a permeability boundary condition at the water-permeable wall was analyzed using the finite element code FTSP. The results show an increase of luminal ADP surface concentration in the upstream and in the downstream tube of the sudden expansion geometry in the range of six and twelve percent of the bulk flow concentration. The effect of flow separation in the downstream tube on the wall concentration is a decrease of about ten percent of the difference between wall concentration and bulk concentration occurring at nearly fully developed flow at the downstream region at a distance of 66 downstream tube diameters from the expansion. The decrease of ADP flux into the wall is in the range of three percent of the flux at the downstream region.

Experimental validation of convection-diffusion discretisation scheme employed for computational modelling of biological mass transport

“…The results were then compared to concentrations obtained experimentally from the direct spectrophometric concentration measurement technique. This experimental methodology is similar to that conducted by Lutostansky et al., 2003, who compared experimental results in a sudden expansion flow chamber to those obtained using an in house developed FE code and Fluent [22]. The findings indicated a positive correlation between the finite element, finite volume and experimental results.…”

“…The findings indicated a positive correlation between the finite element, finite volume and experimental results. However, only one FV discretisation scheme was evaluated by Lutostansky et al , 2003 [22]. In this study, four discretisation schemes were analysed and compared to experimental data.…”

EGF as a New Therapeutic Target for Medulloblastoma Metastasis

“…The bridged μ Lane system operates via a combination of uniaxial bulk convection and diffusion to achieve controlled chemical concentration gradients over time, as described previously (2, 32, 33) . This mass transfer mechanism termed as convective-diffusion has been widely-studied by several groups for bioengineering applications, to determine the transport of differently sized solutes and proteins through the walls of capillaries (11, 12, 20) and arteries (25, 30, 39, 66, 80) , skeletal muscle fibers (31, 35, 45) , and intervertebral discs (18, 62, 63) . The two-dimensional mass transport of ligands within the microsystem was modeled via finite-element-analysis (FEM) in Matlab 7.7 (MathWorks, Natick, MA) and verified experimentally as described previously by our group (32, 33) .…”

Fluid Flow in Distensible Vessels

“…With solute transport Although solute transport prediction is of concern in arterial disease, 37 most work in this area has had pulmonary gas transport in mind. The two situations are substantially different, because solutes and momentum have comparable diffusivity in gases, but solute diffusivity is relatively tiny in liquids.…”