Biorheology - Volume 20, issue 2

Authors: Omenyi, S.N. | Snyder, R.S.

Article Type: Research Article

Abstract: The fractionation of micron-size particles according to physical properties of size, density and surface characteristics by centrifugation and electrophoresis is hindered when the particles behave collectively rather than individually. The formation and sedimentation of droplets containing particles is an extreme example of collective behavior and a major problem for these separation methods when large quantities of particles need to be fractionated. In this paper, experiments that measured droplet sizes and settling rates for a variety of particles and droplets are described. Expressions are developed relating the particle concentration in a drop to measurable quantities of the fluids and particles. The …number of particles in each droplet was then estimated along with the effective droplet density and certain trends are noted. Since a major application of this work is the purification of biological cells in the range of 10 microns, for which monodisperse inert particles are not available, red blood cells from different animals fixed in glutaraldehyde provided model particle groups with the necessary size range, visibility and stability for these fluid dynamical studies. Show more

Keywords: Droplets, settling of, droplet formation and sedimentation, effective droplet density, erythrocytes, glutaraldehyde-fixed, settling rates, solid volume fraction

DOI: 10.3233/BIR-1983-20201

Citation: Biorheology, vol. 20, no. 2, pp. 109-118, 1983

Authors: Karino, Takeshi | Motomiya, Mineo

Article Type: Research Article

Abstract: A novel technique to prepare isolated transparent natural blood vessels was developed and used to study the detailed flow patterns in some regions of the circulation. It was found that paired spiral secondary flows and recirculation zones form downstream of venous valves, at the arterial T-junctions in the dog abdominal aorta, and in the human carotid sinus over a wide range of geometrical and flow conditions, including the time-averaged mean values of the physiological flow rates.

Keywords: Transparent vessel, Venous valve, Bifurcation, Flow pattern, Thrombosis, Atherosclerosis

DOI: 10.3233/BIR-1983-20202

Citation: Biorheology, vol. 20, no. 2, pp. 119-127, 1983

Authors: Zborowski, Maciej

Article Type: Research Article

Abstract: Mass transfer of a solute of small molecular weight across a hydrophilic membrane is discussed and a simplification of the mass transfer analysis is proposed. It was assumed that the permeability of the boundary layer at the membrane surface depends only on the velocity gradient at that membrane surface. Theoretical results are compared with the values of oxygen output at the dialysis membrane activated with an inorganic catalyst, in the presence of hydrogen peroxide, inside a test chamber of a simple geometry and in the flat plate dialyzer. Test chamber data and the theoretical analysis allow for the prediction of …the mass transfer efficiency of the dialyzer. Show more

Keywords: mass transfer, membrane permeability

DOI: 10.3233/BIR-1983-20203

Citation: Biorheology, vol. 20, no. 2, pp. 129-140, 1983

Authors: Rampling, M.W. | Challoner, Teresa

Article Type: Research Article

Abstract: The viscosity: shear rate relationship of whole blood is shown to be described to a good approximation by a bi-linear plot on log: log axes. This has allowed an analytical solution to be obtained which gives a full description of the flow properties of blood in rigid tubes of a size where the Fahraeus-Lindqvist effect is minimal As a result the profound effects that changing haematocrit has on blood flow in such tubes can be quantitated. The analysis also Shows that in similar circumstances altering fibrinogen concentration is of rheological significance only at flow rates below the normal physiological range.

Keywords: Blood flow, fibrinogen, haematocrit, haemorheology, viscosity

DOI: 10.3233/BIR-1983-20204

Citation: Biorheology, vol. 20, no. 2, pp. 141-152, 1983

Authors: Srivastava, L.M. | Srivastava, V.P. | Sinha, S.N.

Article Type: Research Article

Abstract: The problem of peristaltic transport of a fluid of variable viscosity in a non-uniform tube and channel has been investigated under zero Reynolds number, and long wavelength approximation. It is found that, the pressure rise decreases as the fluid viscosity decreases at zero flow rate, is independent of viscosity variation at a certain value of flow rate, and increases if flow rate exceeds further. The difference between two corresponding values (for constant and variable viscosity) of pressure rise, under a given set of conditions increases with increasing amplitude ratio at zero flow rate. Further, for a given zero pressure rise, …the flow rate increases as viscosity of fluid decreases. The pressure rise, in the case of non-uniform geometry is found to be much smaller than the corresponding value in the case of uniform geometry. In Part II (a companion paper), results for uniform tube and channel are obtained and comparison with other theories are made in detail. Finally, the models developed in Part I and Part II are applied and compared with observed flow rates in vas deferens of rhesus monkeys, the small intestine, and the ductus efferentes of the male reproductive tract in the other companion paper, Part III. Show more

Keywords: Peristaltic transport, Physiological fluid, Flow, Non-uniform Geometry

DOI: 10.3233/BIR-1983-20205

Citation: Biorheology, vol. 20, no. 2, pp. 153-166, 1983

Authors: Srivastava, L.M. | Srivastava, V.P. | Sinha, S.N.

Article Type: Research Article

Abstract: Using the model of peristaltic flow in non-uniform geometry, developed in the companion paper (Part I), results for uniform tube and channel are obtained in closed form. Comparison of analysis with other theories and the effect of viscosity variation are discussed in detail. Finally, quantitative comparison are made between theory and experiments of Weinberg et al. and Latham.

Keywords: Peristaltic transport, Physiological fluid, Flow, Uniform geometry

DOI: 10.3233/BIR-1983-20206

Citation: Biorheology, vol. 20, no. 2, pp. 167-178, 1983

Authors: Srivastava, L.M. | Srivastava, V.P. | Sinha, S.N.

Article Type: Research Article

Abstract: The models of peristaltic flow in non-uniform and uniform tube and channel, developed in the companion papers, Part I and Part II, are applied and compared with the observed flow rates in vas deferens of rhesus monkeys, the small intestine, and the ductus efferentes of the male reproductive tract.

Keywords: Peristaltic transport, Physiological fluid, Applications

DOI: 10.3233/BIR-1983-20207

Citation: Biorheology, vol. 20, no. 2, pp. 179-185, 1983

Authors: Sharma, M.G. | Rafie, S.

Article Type: Research Article

Abstract: A rheological constitutive relation in shear for an apple cortex tissue has been developed based upon creep experiments on solid cylindrical samples of the soft tissue obtained from a specified location of the apple and subjected to constant torques of various magnitudes and duration using a specially developed multiaxial loading device. Results indicate that the material displays non-linear viscoelastic properties which can be characterized by a multiple integral relation between the torque and the unit angle of twist. Using this relation the creep response of the material under two step and three step torque histories and the history with torque …linearly varying with time was predicted and found to agree well with experimental results. Finally, the paper describes a method for obtaining the constitutive relation in shear from the developed unit angle of twist-torque equation. The shear constitutive relation for the tissue has been found to be of the integral type with two kernal functions specifying the rheological response. Show more

Keywords: Viscoelasticity, Nonlinearity, Creep, Rheology, Soft Tissue, Apple Cortex, Kernel Functions, Torsion, Shear Strain, Shear Stress

DOI: 10.3233/BIR-1983-20208

Citation: Biorheology, vol. 20, no. 2, pp. 187-197, 1983

Authors: Hanss, M.

Article Type: Research Article

Abstract: A new filtration technique, based on the initial filtration rate of a diluted RBC suspension through 5μ Nuclepore filter is described. As only a few hundreds RBCs traverse each pore and as the measurement are made in a few seconds, the method is by large insensitive to filter plugging and to sedimentation effects. The results are given as a filtration index IF which is, as a first order approximation, independent of the filter conductance and of the suspending medium viscosity. The filtration times are measured electronically. The filters are re-used many times. The influence on the results reproducibility of …RBC washing, of the anticoagulant, of the blood sample and the suspension storage times are considered. With our technical procedure, the relative incertitude on the measurement of I.F. is about ± 10%. The filtration index is shown to be an intrinsic RBC filterability property. Show more

Keywords: Hemorheology, Blood viscosity, RBC filtrability, RBC deformability, Viscosity measurements

DOI: 10.3233/BIR-1983-20209

Citation: Biorheology, vol. 20, no. 2, pp. 199-211, 1983

Article Type: Announcement

DOI: 10.3233/BIR-1983-20210

Citation: Biorheology, vol. 20, no. 2, pp. 213-214, 1983