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Using Equation ( 5 ) And Comparing Values For Normal Channel Width

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As explained earlier, by using Equation (5) and comparing values for normal channel width having no dots, tortuosity effect can be measured. As the fluid passes through these dots, the length of the contact of wax increases along with the tortuous path, both causing an increase in the channel resistance. This tortuosity increases from 1.34 to 1.54 as the density increases from low to high in case of wax. The high-density value seems to have an almost similar flow profile to the medium density both in the cases of wax and SU-8. This is attributed to the fact that even though the gap between the dots decreased, there are more number of dots than the moving fluid faces, and the tortuous nature of the path significantly decreased. This …show more content…

A detailed study on the rectangular arrangement of dots was performed by varying their density to achieve various flow profiles (Figure 5). This study aims to achieve the configuration possessing the greatest resistance.
Rectangular formations of dots are observed in Figure 5, and their dependence on their respective density. For the low (1.5 mm) to medium (1.15 mm) density transition, the flow is reduced as expected. However, a different result is obtained by further increasing the density. Interestingly, as the density is increased to 0.65 mm, the flow seems to get faster as compared to the medium and low density. This odd result can be explained by looking at the flow the oil progressing inside the channel. A greater density would mean lesser distance in between the successive dots. This would result in an increased oleophilic clinging action of oleic acid and more importantly as the dots come closer, the channel seems to divide itself in three smaller channels and thereby reducing the tortuous path. Although the resistance factor is still there, the tortuous path is reduced, thus increasing the flow velocity. As compared to the plain channel, the flow is still slower as shown in Figure 5. This decrease can be noted in terms of time taken to travel a certain distance. This distance chosen for study was 26.25 mm. In the case of low density of 1.15 mm, the time was 4,670 s. The time

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