Prediction and Simulation on the Shear Stress and Mass Transfer in Perfused Bioreactors 11: Effect of Feed Mode and Bioreactor Geometry

2008 ◽  
Author(s):  
Kedian Wang ◽  
Xia Dong
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Feed Mode ◽  
Prediction And Simulation

Mass transfer into boundary layers for power law fluids

1979 ◽  
Vol 365 (1722) ◽  
pp. 313-326 ◽  
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Shear Stress ◽  
Boundary Value Problem ◽  
Wall Friction ◽  
Point Boundary ◽  
Boundary Layer Equations ◽  
Mass Injection ◽  
Power Law Fluids ◽  
Similarity Preserving

The boundary layer equations for the class of non-Newtonian fluids having the shear stress proportional to a power of the strain rate are considered under conditions of similarity-preserving mass transfer at the wall. The adoption of Crocco variables results in a nonlinear, two point boundary value problem for which existence, uniqueness and analyticity are established. In the case of mass injection particular attention is paid to boundary conditions corresponding to the vanishing of the wall friction and values for the (possibly non-existent) critical injection rates are exhibited.

Distribution of Mass Transfer Rate and Wall Shear Stress Behind Simple Rectangular Stenosis in Pulsating Flow

1989 ◽  
Vol 111 (1) ◽  
pp. 47-54 ◽  
Author(s):  
R. Yamaguchi
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Transfer Rate ◽  
Schmidt Number ◽  
Fluid Dynamic ◽  
Mass Transfer Rate ◽  
Pulsating Flow ◽  
Flow Through ◽  
Wall Shear

The distributions of mass transfer rate and wall shear stress in sinusoidal laminar pulsating flow through a two-dimensional asymmetric stenosed channel have been studied experimentally and numerically. The distributions are measured by the electrochemical method. The measurement is conducted at a Reynolds number of about 150, a Schmidt number of about 1000, a nondimensional pulsating frequency of 3.40, and a nondimensional flow amplitude of 0.3. It is suggested that the deterioration of an arterial wall distal to stenosis may be greatly enhanced by fluid dynamic effects.

Enhancement of Turbulent Shear Stress and Mass Transfer in Wall Turbulence Accompanied With Wall Blowing

2016 ◽  
Author(s):  
Yushi Okamura ◽  
Hideaki Sugioka ◽  
Yasuo Kawaguchi
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Spatial Distribution ◽  
Solid Wall ◽  
Structural Parameters ◽  
Wall Turbulence ◽  
Experimental Result ◽  
Turbulent Shear ◽  
Eddy Structure ◽  
Turbulent Schmidt Number

Spatial distribution of velocity and mass concentration fluctuation in turbulent channel flow with wall blowing were simultaneously measured by PIV/PLIF. The recorded pictures were analyzed to clarify the turbulent momentum and mass transfer from statistical view point and from spatial evolution of coherent eddy structure. Experimental result revealed that the Reynold shear stress and turbulent intensity are enhanced as the blowing rate increasing. On the other hand, structural parameters based on local turbulence such as turbulent Schmidt number and a degree of turbulent anisotropy is not affected by wall blowing. In comparison without wall blowing, we found that the turbulent eddy structure locates apart from the wall. Besides, energy spectrum and swirling strength is also enhanced by wall blowing. It is associated with increase of resistance by wall blowing. Generally in wall turbulence, fluctuation motions are restricted by the presence of solid wall. But for the blowing from the wall relaxes this restriction and Reynolds shear stress is enhanced, which leads to enhancement of turbulent mass flux. Moreover, from results of spatial distribution of instantaneous fields, wall-blowing helps development of hairpin vortexes. It is concluded that development of hairpins leads to enhancement of turbulent mass transfer.

scholarly journals Lagrangian wall shear stress structures and near-wall transport in high-Schmidt-number aneurysmal flows

2016 ◽  
Vol 790 ◽  
pp. 158-172 ◽  
Author(s):  
Amirhossein Arzani ◽  
Alberto M. Gambaruto ◽  
Guoning Chen ◽  
Shawn C. Shadden
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Shear Stress ◽  
Vector Field ◽  
Wall Shear Stress ◽  
Residence Time ◽  
Vessel Wall ◽  
Schmidt Number ◽  
High Schmidt Number ◽  
Near Wall

The wall shear stress (WSS) vector field provides a signature for near-wall convective transport, and can be scaled to obtain a first-order approximation of the near-wall fluid velocity. The near-wall flow field governs mass transfer problems in convection-dominated open flows with high Schmidt number, in which case a flux at the wall will lead to a thin concentration boundary layer. Such near-wall transport is of particular interest in cardiovascular flows whereby haemodynamics can initiate and progress biological events at the vessel wall. In this study we consider mass transfer processes in pulsatile blood flow of abdominal aortic aneurysms resulting from complex WSS patterns. Specifically, the Lagrangian surface transport of a species released at the vessel wall was advected in forward and backward time based on the near-wall velocity field. Exposure time and residence time measures were defined to quantify accumulation of trajectories, as well as the time required to escape the near-wall domain. The effect of diffusion and normal velocity was investigated. The trajectories induced by the WSS vector field were observed to form attracting and repelling coherent structures that delineated species distribution inside the boundary layer consistent with exposure and residence time measures. The results indicate that Lagrangian WSS structures can provide a template for near-wall transport.

scholarly journals Oxygen mass transfer in a model three-dimensional artery

2008 ◽  
Vol 5 (26) ◽  
pp. 1067-1075 ◽  
Author(s):  
G Coppola ◽  
C Caro
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Vessel Wall ◽  
Three Dimensional ◽  
Oxygen Mass Transfer ◽  
Dimensional Model ◽  
Flow Conditions ◽  
Human Coronary Artery ◽  
Three Dimensional Model ◽  
Physiological Flow

Arterial geometry is commonly non-planar and associated with swirling blood flow. In this study, we examine the effect of arterial three-dimensionality on the distribution of wall shear stress (WSS) and the mass transfer of oxygen from the blood to the vessel wall in a U-bend, by modelling the blood vessels as either cylindrical or helical conduits. The results show that under physiological flow conditions, three-dimensionality can reduce both the range and extent of low WSS regions and substantially increase oxygen flux through the walls. The Sherwood number and WSS distributions between the three-dimensional helical model and a human coronary artery show remarkable qualitative agreement, implying that coronary arteries may potentially be described with a relatively simple idealized three-dimensional model, characterized by a small number of well-defined geometric parameters. The flow pattern downstream of a planar bend results in separation of the Sh number and WSS effects, a finding that implies means of investigating them individually.

Direct Measurement of Wall Shear Stress With Mass Transfer in a Low Speed Boundary Layer

1977 ◽  
Vol 99 (3) ◽  
pp. 580-584 ◽  
Author(s):  
K. Depooter ◽  
E. Brundrett ◽  
A. B. Strong
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Shear Stress ◽  
Porous Plate ◽  
Feedback System ◽  
Direct Measurements ◽  
Porous Element ◽  
Floating Element ◽  
Asymptotic Suction ◽  
Suction And Blowing

A porous plate floating element is used to obtain direct measurements of shear stress in a transpired zero pressure gradient boundary layer from laminar asymptotic suction to blow-off. The thrust balance incorporates a feedback system which provides self centering of the porous element from zero shear stress up to the maximum encountered. Shear stress data obtained for suction and blowing conditions agree well with previously determined indirect data. The floating element data are well correlated by two equations, one for the suction mode, and one for the blowing mode, via simple modifications of an existing correlation.

Mass-Transfer Method of Measuring Wall Shear Stress in Supersonic Flow

1965 ◽  
Vol 8 (9) ◽  
pp. 1641 ◽  
Author(s):  
Ahmed R. Wazzan ◽  
A. M. O. Smith ◽  
R. C. Lind
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Supersonic Flow ◽  
Wall Shear Stress ◽  
Wall Shear ◽  
Transfer Method
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