Biorheology - Volume 20, issue 3

Authors: Copley, Alfred L.

Article Type: Editorial

DOI: 10.3233/BIR-1983-20301

Citation: Biorheology, vol. 20, no. 3, pp. 263-265, 1983

Authors: Sutera, S.P. | Tran Son Tay, R.

Article Type: Research Article

Abstract: The velocity field external to a stationary ellipsoidal particle with continuously rotating surface motion driven by a surrounding shear flow is calculated. The configuration is intended to model the so-called “tank-treading” behavior of mammalian erythrocytes (red cells) when suspended in shear flow. The boundary-value problem posed is based on the model developed by Keller & Skalak (7) and is solved by adapting Jeffrey’s general solution (9) for the Stokes flow about a rigid, freely rotating ellipsoid immersed in an unbounded viscous flow. Streamlines and velocity profiles in the plane of symmetry are obtained by numerical computations. The flow pattern reveals …two free stagnation points near the ends of the particle and the streamlines branching from these points delineate a region of closed streamlines surrounding the particle and two recirculating wakes extending to infinity both upstream and downstream of the particle. The presence of the wakes suggests a mechanism for enhanced diffusion of smaller solute particles in the surrounding fluid. Show more

Keywords: red cell, tank-treading, velocity field

DOI: 10.3233/BIR-1983-20302

Citation: Biorheology, vol. 20, no. 3, pp. 267-282, 1983

Authors: Secomb, T.W. | Fischer, T.M. | Skalak, R.

Article Type: Research Article

Abstract: Experimental and theoretical results are presented concerning the motion of close-packed red blood cell suspensions subjected to steady simple shear flow. The behavior of the suspension was observed microscopically using a cone-and-plate rheoscope. At moderate and high shear rates the cells show a fairly orderly arrangement, each appearing polygonal in the field of view. An idealized theoretical model for the suspension is developed, in which each cell is a 14-sided polyhedron of varying shape, but with constant surface area and volume. Tank-treading motion of the membrane is predicted, and an approximation to the motion is calculated which is consistent with …the known mechanical properties of the membrane. It is shown that considerably more energy is dissipated in the membrane than in the cytoplasm during tank-treading. Show more

Keywords: rheology, red blood cells, shear flow, tank-treading

DOI: 10.3233/BIR-1983-20303

Citation: Biorheology, vol. 20, no. 3, pp. 283-294, 1983

Authors: Secomb, T.W. | Chien, S. | Jan, K.-M. | Skalak, R.

Article Type: Research Article

Abstract: A theoretical analysis is made of the dynamical behavior and bulk rheology of close-packed red blood cell suspensions subjected to simple shear flow. The model far the polyhedral cell shapes and tank-treading membrane motion developed in the companion paper (1) is used. The flow in the thin lubricating plasma layers between cells is analyzed taking into account the mechanical properties of the membrane at the corner regions of sharp membrane curvature. This leads to predictions for the apparent viscosity as a function of hematocrit and shear rate. Good agreement with experimental results is obtained at moderate and high shear rates …(above 20 s−1 ). At lower shear rates, a rapid rise in apparent viscosity has been found experimentally, and the mechanisms leading to this behavior are examined. Show more

Keywords: rheology, red blood cells, blood viscosity, tank-treading

DOI: 10.3233/BIR-1983-20304

Citation: Biorheology, vol. 20, no. 3, pp. 295-309, 1983

Authors: Skalak, R. | Hanss, M. | Chien, S.

Article Type: Research Article

Abstract: A number of different experimental techniques have been devised in recent years to use microsieving as a test of the filterability of suspensions of red blood cells. Various indices have been proposed to express the results of these tests. In the present paper a correlation is made of the intrinsic increase in resistance at the level of a single pore in the filter to the macroscopically observed pressure and flow through the entire filter. Further it is shown how a number of different tests may be used to derive the same index. The results apply only to situations in which …there is no plugging of pores. Show more

Keywords: filterability, red cells, microsieving, steady flow theory, pore plugging

DOI: 10.3233/BIR-1983-20305

Citation: Biorheology, vol. 20, no. 3, pp. 311-316, 1983

Authors: Richardson, P.D. | Lazzara, S.

Article Type: Research Article

Abstract: Experiments were performed to study the rheological response of human blood at hematocrit ratios of 0 to 0.45 in axial oscillatory flow in a tube of uniform bore. Three principal regimes of flow were identified, depending on the amplitude of oscillation. At the highest amplitudes (and therefore the largest range of shear rates in the blood) there was turbulent motion and the friction coefficient increased in proportion to the square of the hematocrit. At small amplitudes the friction decreased with increase in amplitude, the rate of decrease increasing with hematocrit. At intermediate amplitudes the friction increased in proportion to the …square of the hematocrit. Glutaraldehyde fixation of the red cells caused increase in the friction, and reduced the rate of decrease of friction with amplitude at small amplitudes. With a stenosis of very modest degree and span the friction in normal blood increased disproportionately, and a small blind hole in the lumen of the stenosis caused additional and disproportionate increase in friction. Show more

Keywords: axial oscillatory flow, friction coefficient, glutaraldehyde REC fixation, hematocrit, human blood, turbulent motion

DOI: 10.3233/BIR-1983-20306

Citation: Biorheology, vol. 20, no. 3, pp. 317-326, 1983

Authors: Fu-lung, Liao | Dintenfass, L.

Article Type: Research Article

Abstract: Flow instability (formation of vortices and a concurrent increase in the apparent viscosity) was studied in the rotational rhombospheroid viscometer of 3°, 5° and 10° gaps over a range of speeds from 10 to 300 r.p.m.. Comparisons between different blood systems were carried out mainly at 250 r.p.m. Experiments were carried out on blood samples obtained directly from human subjects, or from the Blood Bank, or from horses. Reconstituted suspensions of red cells in albumin or dextran were also used. Apparent flow instability was found to be not solely a function of blood viscosity, but a multiple function of many viscosity factors …or blood subphases, including instability-decreasing factors such as haematocrit and aggregation of red cells; and instability-increasing factors such as rigidity of red cells; and thus specific to and characteristic of individual blood samples. Apparent instability can be described by multiple regressions as a function, Z, of red cell rigidity, Tk, blood viscosity, η app , and aggregation of red cells, AG; for example: Z = − 28.29 + 26.24 Tk + 0.109 η app (r = 0.816; P < 0.001), or Z = 5.90 − 0.0165 AG − 0.752 η app (r = 0.573; P < 0.05). The apparent instability can be seen only in one-third of blood samples obtained from horses, and in more than half of blood samples obtained from human donors; majority of human donors shows apparent instability below 3 per cent. Show more

Keywords: Flow instability, Blood viscosity, RBC rigidity, Haematocrit, Human blood, Horses blood

DOI: 10.3233/BIR-1983-20307

Citation: Biorheology, vol. 20, no. 3, pp. 327-342, 1983

Authors: Seaman, G.V.F.

Article Type: News

DOI: 10.3233/BIR-1983-20308

Citation: Biorheology, vol. 20, no. 3, pp. 343-344, 1983

Article Type: Correction

DOI: 10.3233/BIR-1983-20309

Citation: Biorheology, vol. 20, no. 3, pp. 345-345, 1983

Article Type: Announcement

DOI: 10.3233/BIR-1983-20310

Citation: Biorheology, vol. 20, no. 3, pp. 347-347, 1983