Biorheology - Volume 18, issue 2 - Journals

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Last Call to Participate in the 4. International Congress of Biorheology, Tokyo, Japan, 27. July to 1. August, 1981

Authors: Copley, A.L.

Article Type: Other

DOI: 10.3233/BIR-1981-18201

Citation: Biorheology, vol. 18, no. 2, pp. 189-189, 1981

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Effect of flow instability (and of blood anti-instability properties) on viscosity of blood measured in rotational viscometer

Authors: Dintenfass, Leopold | Fu-lung, Liao

Article Type: Research Article

Abstract: Flow instability has been observed in the plasma and in the blood of low haematocrit studied in the rotational rhombospheroid viscometer. As this observation is relevant, and fundamental, to all cone-in-cone and cone-and-plate viscometers, a detailed experimental series was carried out using a range of standard oils of different viscosities as well as blood of different haematocrits. The main attention was given to a shear rate of 180 sec−1 , corresponding to 250 r.p.m. at angular gap of 5° (although a 10° gap has been also used). Linear regressions have been established for flow instability (given as percentage increase of the apparent …viscosity). The linear regression for Newtonian oils was: y = −0.1258x + 1.962 ± 0.133, (r = −0.981); and for blood: y = −0.354x + 2.002 ± 0.116, (r = −0.983), in which y represents log of percentage increase of viscosity due to instability, and x is viscosity in cP or mPas.s. Flow instability occurs at higher shear rates in blood than in Newtonian oils; this is attributed to the pseudoplasticity (or shear-thinning or thixotropy) of blood. Both regressions merge at viscosity of under 1 cP, and spread apart as viscosities increase. Show more

Keywords: Flow instability, Newtonian oils, Blood anti-instability property

DOI: 10.3233/BIR-1981-18202

Citation: Biorheology, vol. 18, no. 2, pp. 191-205, 1981

Price: EUR 27.50

On phenomenological mechanochemical muscle models – I

Authors: Long, R.L. | McIntire, L.V.

Article Type: Research Article

Abstract: Two kinetic models of the calcium-ATP-actomyosin interaction in muscle tissue are developed. The assumptions made in this work are based firmly on the experimental data available in the literature. Using these models, the rate equations for hydrolysis and formation of activated actomyosin complex are found. An important result is that rate of change of concentrations for all species in this complex set of biochemical reactions can be expressed in terms of two species rate equations. The remaining concentrations are related to these through equilibrium and species continuity (mass conservation) relations. In Part II, these models are used to develop general …thermodynamic constitutive models for striated muscle. Show more

Keywords: Muscle rheology, mechanochemical models, contraction

DOI: 10.3233/BIR-1981-18203

Citation: Biorheology, vol. 18, no. 2, pp. 207-222, 1981

Price: EUR 27.50

On phenomenological mechanochemical muscle models – II

Authors: Long, R.L. | McIntire, L.V.

Article Type: Research Article

Abstract: Using the kinetic models developed in Part I, a set of general continuum thermodynamic constitutive equations of the internal state variable type are proposed for striated muscle tissue and analyzed. Restrictions put on the arguments of the stress tensor, heat flux vector, free energy and reaction rate expressions are deduced using general arguments of tensor invariance, material symmetry and the entropy inequality. Comparison for the special case of one dimensional linearized irreversible thermodynamic analysis is made with results of previous workers.

Keywords: Muscle rheology, mechanochemical models, contraction, irreversible thermodynamics

DOI: 10.3233/BIR-1981-18204

Citation: Biorheology, vol. 18, no. 2, pp. 223-233, 1981

Price: EUR 27.50

A critical study of Poiseuille flow of couple stress fluid with applications to blood flow

Authors: Chaturani, P. | Rathod, V.P.

Article Type: Research Article

Abstract: In this paper, the Poiseuille flow of couple stress fluid has been critically examined. It is shown that the method used for comparing the theoretical and experimental results is erroneous and the values of the couple stress parameters obtained for blood flow are incorrect. The existing method for determining the couple stress parameters has been improved. The computational work in the improved method is considerably less. It is observed that both the couple stress parameters are functions of concentration c and an empirical relation between concentration, α ¯ and η ¯ …has been obtained. It is of interest to note that the shear viscosity μ and non-dimensional axial velocity are functions of concentration. This is in contrast with the existing result, i.e., μ is independent of c and non-dimensional axial velocity is insensitive of c(α ¯ ). Finally, some uses of determining the values of α ¯ and η ¯ have been suggested. Show more

Keywords: Viscosity, velocity profiles, blood flow

DOI: 10.3233/BIR-1981-18205

Citation: Biorheology, vol. 18, no. 2, pp. 235-244, 1981

Price: EUR 27.50

A two-fluid model for blood flow through small diameter tubes with non-zero couple stress boundary condition at interface

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

Article Type: Research Article

Abstract: The present problem deals with a two-fluid model for blood flow through narrow tubes. The model basically consists of a core (substructured continuum) and a peripheral layer of plasma (Newtonian fluid). A new boundary condition has been introduced which takes into account a more realistic situation, that is, non-zero couple stresses at the interface. Analytical expressions have been obtained for axial velocity relative particle spin flow rate and apparent viscosity. A critical study of other theoretical models and their comparison with the present model has been presented. Further, the results of the present model are in reasonably good agreement with …the experimental observations. It is of interest to note that the present model can be used to explain Segre-Silberberg effect, Fahraeus-Lindquist effect and blunting of velocity profiles whereas most of the other models can explain only one or two of these anomalies. Show more

Keywords: Viscosity, velocity profiles, blood flow

DOI: 10.3233/BIR-1981-18206

Citation: Biorheology, vol. 18, no. 2, pp. 245-253, 1981

Price: EUR 27.50

A model for erythrocyte sedimentation

Authors: Hill, C.D. | Bedford, A.

Article Type: Research Article

Abstract: The concentration profile of erythrocytes during sedimentation is predicted by using equations for two-phase flow. The equations model the buoyant force on the cells, the drag due to the relative motion of the cells and the plasma, and the diffusive force on the cells due to their Brownian motion. The equations are solved by the method of finite differences and the results are compared to the experimental data of Whelan, Huang, and Copley. The results indicate that a theory of this type can accurately predict the measured concentration profiles. However, in order to do so, an anomalously large value of …the diffusivity coefficient must be used. Show more

Keywords: Blood sedimentation, Blood viscosity, Erythrocyte aggregation

DOI: 10.3233/BIR-1981-18207

Citation: Biorheology, vol. 18, no. 2, pp. 255-266, 1981

Price: EUR 27.50