It is necessary to consider both relaxation time and viscosity for investigating viscoelastic flow. Polyethylene flow from a reservoir into a slit at low Reynolds numbers has been visually observed to investigate the flow patterns.
The results of this study are as follows:
When Reynolds number is smaller than 1, circulating secondary flow appears or disappears depending upon the conditions of the main flow and of the characteristics of melted polymers.
The liquid having longer rexation time has a lower critical deformation velocity at which the circulating secondary flow occurs in the reservoir. The region of circulating secondary flow spreads out as the deformation velocity becomes higher. Although the slit entry angle changes, the patterns of main flow into the slit hardly change. In regard to the liquid having shorter relaxation time, irregular and unstable flow occurs at the inlet region of the slit before the circulating secondary flow appears.

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The numerical analysis using the vorticity and the stream function is so useful to study two-dimensional viscous liquid flows that many problems have been solved by this method. In the present paper, this method has been expanded to two-dimensional viscoelastic liquids, and, as an example, the flow of a viscoelastic liquid into a slit has been calculated by using the Maxwell model.
Comparing the results of numerical calculations with those of experiments, we found that the former agreed well with the latter. From this fact, it is clear that this numerical analysis is valid for the study of viscoelastic liquid flows.
As it is easy to change the constitutive equations in this method, this method is applicable to the analysis of many viscoelastic flows.

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The thermal conductivity of wet fabrics parallel to warps (K_w; ) and normal to the fabric surface (K_v; ) were measured by a line heat source method. The results obtained when pl, the volume fraction of water in interfiber spaces, is between 0 and 1, are as follows:
(1) The relation between K_v; and pl is approximately expressed by a quadratic curve, and that between K_w; and pl by a straight line. (2) The specific heat of wet fabrics calculated by the thermal properties of their components agrees well with the experimental values. (3) For 0<pl<1, the thermal conductivity of wet fabrics can be estimated from equations (2), (3), (4) and (5) except hairy fabrics of wool.

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