Gel-walled cylindrical channels as models for the microcirculation: dynamics of flow¹

Article type: Research Article

Authors: Lahav, J. | Eliezer, N. | Silberberg, A.

Affiliations: Polymer Department, Weizmann Institute of Science, Rehovot, Israel

Note: [1] 1st International Congress of Biorheology, Lyon, France, 4–8 September 1972

Abstract: Vessels in the microcirculation have been compared to channels in a gel. In this study a method has been developed whereby a geometrically well defined section of a flow system was composed of a cylindrical gel mantic of outer radius RG, surrounding a cylindrical channel of radius R. Both the channel and the mantle were of length L and were contained in a rigid transparent support of inner radius RG. Hence RG and L were fixed (RG = 1.3 or 4.5 mm; L = 40 mm) and the radius R ≃ 0.14 mm could be measured by mounting the whole system on the stage of a microscope fitted with an eye-piece micrometer. The gel was crosslinked polyacrylamide swollen with water. Water also served as the flow medium. It was found that R increased with absolute pressure applied statically to the system under no flow conditions. In flow the channel tended to expand upstream and contract down stream. Flow rate Q through the system and pressure drop ΔP were measured and the radius of the channel was monitored as a function of distance x along its length. At low pressure gradients now rates Q agreed with the theoretically predicted flow rates Qo but dropped below Qo at higher pressure gradients even though allowance was made for changes in R in calculating Qo and flow was shown to be laminar. The extent of the deviation decreased with gel rigidity G′ and increased with thickness of the gel wall RG − R. The results expressed as Q/Qo could be correlated when plotted as a function of α=(RG/2LG′)ΔP, and corresponded approximately to the function Q/Qo=(1−α)4. The relevance of these results for the microcirculation is discussed.

DOI: 10.3233/BIR-1973-10413

Journal: Biorheology, vol. 10, no. 4, pp. 595-604, 1973