Biorheology - Volume 14, issue 5-6

Authors: Copley, A.L. | Scott Blair, G.W.

Article Type: Editorial

DOI: 10.3233/BIR-1977-145-601

Citation: Biorheology, vol. 14, no. 5-6, pp. 215-215, 1977

Authors: Papenfuss, Heinz D. | Gross, Joseph F.

Article Type: Research Article

Abstract: This work is a theoretical study of the viscosity changes due to transmural fluid exchange in permeable blood vessels and their influence on the filtration rate. Two effects are considered: (i) Variation of the tube hematocrit along the vessel axis which leads to a concomitant variation of the suspension viscosity. (ii) Variation of the total plasma protein concentration along the capillary axis which changes the plasma viscosity. For the first effect, experimental data of Barbee and Cokelet for tube diameters of 29–221 μ m are used for the theoretical model. For capillaries of smaller diameters, the “stacked-coins model” is used …to simulate the single-file flow of the red cells. A fictitious reservoir approach is proposed to determine the Fåhraeus and Fåhraeus–Lindqvist effects for permeable blood vessels. Results for the rat glomerulus show that the blood viscosity increases along the capillaries due to filtration by as much as 60%. However, this fluid mechanical change affects the filtration fraction be less than 2%, compared with results for earlier models which use the assumption of constant blood viscosity. Show more

DOI: 10.3233/BIR-1977-145-602

Citation: Biorheology, vol. 14, no. 5-6, pp. 217-228, 1977

Authors: Lai, W. Michael | Kuei, Steve C. | Mow, Van C.

Article Type: Research Article

Abstract: Relaxation spectra and relaxation functions are calculated for some synovial fluids using the dynamic moduli data available in the literature. The importance of the relaxation function in relation to the rheological equation of state, both linear and nonlinear, is noted. Further, the calculation shows that a pathological synovial fluid can have a much shorter relaxation time than the fluid from young healthy specimens. Calculations of apparent viscosities for some synovial fluids are also made using the nonlinear BKZ rheological equation with the relaxation spectra obtained from the dynamic moduli. This procedure yields good agreement between the calculated result and experimental …data. Show more

DOI: 10.3233/BIR-1977-145-603

Citation: Biorheology, vol. 14, no. 5-6, pp. 229-236, 1977

Authors: Chaturani, P. | Upadhya, V.S.

Article Type: Research Article

Abstract: The gravity flow of a fluid with couple stress along an inclined plane has been studied. The velocity profiles for various values of Reynolds number, inverse Frouds number, inclination angle and couple stress parameter ‘a’ have been shown graphically. It is shown that gravity flow experiments could be used to determine the couple stress parameter η and the slip velocity in blood flow. Further, these experiments might be used for obtaining the flow curve for blood.

DOI: 10.3233/BIR-1977-145-604

Citation: Biorheology, vol. 14, no. 5-6, pp. 237-246, 1977

Authors: Dintenfass, Leopold | Kammer, Sylvia

Article Type: Research Article

Abstract: Plasma viscosity was studied at 37°C by means of Coulter Automatic Capillary Viscometer. EDTA blood was obtained from 615 subjects, including normals as well as patients with peripheral vascular disease, retinopathy, and malignant melanoma. The aim of this study was to explore relationships between plasma viscosity and levels of fibrinogen, cholesterol and globulin, and establish viscosity values for 37°C. Values for plasma viscosity at 37°C were determined for the whole series (1.261 cP ± 0.118), and for the five subgroups. The highest significance was observed between plasma viscosity and globulin level (P < 0.0001 ), and then …between plasma viscosity and fibrinogen level (P < 0.001 ). Cholesterol contribution was not significant either for the whole series or for most subgroups. In most subgroups globulin level was of greater importance than the fibrinogen level. Error of estimate (standard deviation from regression) was 0.11 cP for the whole series, and from 0.06 to 0.15 cP in different subgroups. Show more

DOI: 10.3233/BIR-1977-145-605

Citation: Biorheology, vol. 14, no. 5-6, pp. 247-251, 1977

Authors: Deutsch, S. | Phillips, W.M.

Article Type: Research Article

Abstract: An attempt is made to validate the hypothesis made by the authors (Phillips and Deutsch, Biorheology 12 (1975), 383.), that a four constant Oldroyd constitutive equation is sufficient to characterize the constitutive behavior of blood. The validation proceeds by the comparison of theoretical predictions with experimental results for the problem of stability to small disturbances in circular Couette flow. The paper describes the development of a unique Taylor-Couette device and the comparison for 40% hematocrit whole human blood. Elasticity is found to have a substantially stabilizing effect on blood behavior. The constitutive model is found to be quantitatively …inadequate and some results toward a higher order quantitatively adequate model are presented. It is suggested that a stress relaxation time of ca . 3 sec and a strain rate retardation time of 0.75 sec may have some meaning, in a suitably defined average sense, for normal hematocrit human blood. The use of these values in qualitative descriptions of the behavior of blood in complex flow situations should be of value. Show more

DOI: 10.3233/BIR-1977-145-606

Citation: Biorheology, vol. 14, no. 5-6, pp. 253-266, 1977

Authors: Bate, Hilary

Article Type: Research Article

Abstract: Blood flow through tubes is best described by the Casson equation in the shear rate range 15–6400 sec−1 , i.e. τ 1 / 2 = k 0 + k 1 γ ˙ 1 / 2 , where τ is shear stress, γ ˙ is shear rate, k 0 and k 1 , are not true constants but vary slowly with shear rate. This equation implies that viscosity coefficient, calculated in the usual manner, will vary with tube …diameter and pressure gradient. It is shown that yield shear stress is not important physiologically. Show more

DOI: 10.3233/BIR-1977-145-607

Citation: Biorheology, vol. 14, no. 5-6, pp. 267-275, 1977

Authors: Dunn, Patrick F. | Picologlou, Basil F.

Article Type: Research Article

Abstract: The results of an investigation of the previously undetermined rheological properties of human semen using a modified, multiple-point capillary viscometer are presented. The design of a viscometer, specifically constructed to give accurate, instantaneous pressure gradient and material flow rate records of biological viscoelastic fluids whose rheological properties are possibly changing with time is given. Using this device, measurements are made on human semen immediately following ejaculation. An analytical scheme for the data reduction, suitable for non-linear viscoelastic fluids of the Maxwell-type, is offered. An expression is developed for a non-linear Maxwell-type viscoelastic fluid flow in a circular tube, …relating the material’s elastic properties to the distance of recoil and the pressure gradient. In the case of a power-law elastic behavior this relation couples the wall shear stress with the recoil distance through an apparent shear modulus. Previously established procedures for the viscous response analysis are utilized and an approximate non-dimensional parameter is introduced allowing one to ascertain the relative contributions of the elastic and viscous components to the rate of flow. Results show the elastic and viscous properties of human semen to be functions of time following ejaculation and frequency of ejaculation. The elastic component is found to have a linear response over the shear stress range investigated, whereas the viscous component is found to exhibit a power-law behavior. The final equilibrium state is characterized by Newtonian behavior, with mean absolute viscosity of 3.37 centipoise. Finally, similarity among all cases examined is found for each material property through consideration of a nondimensional time, t ∗ , determined from semen liquefaction time and time post ejaculation. Show more

DOI: 10.3233/BIR-1977-145-608

Citation: Biorheology, vol. 14, no. 5-6, pp. 277-292, 1977

Authors: Sabikowski, Z.T. | Hutchings, R.T.

Article Type: Other

DOI: 10.3233/BIR-1977-145-609

Citation: Biorheology, vol. 14, no. 5-6, pp. 293-294, 1977

Authors: Sabikowski, Hunter

Article Type: Review Article

DOI: 10.3233/BIR-1977-145-610

Citation: Biorheology, vol. 14, no. 5-6, pp. 295-298, 1977