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
9. I filled the pipette with the soapy water solution and began to start adding drops of the solution to the same penny, from the distance of ½ centimeter, at a rate of one drop per second.
Another factor is the Momentum Thickness, ϴ. It is defined as the thickness of a layer of freestream fluid carrying a momentum flow rate equal to the reduction in momentum flow rate caused by the formation of the boundary layer. Closer to the surface of the object, the flow is slower. This means that the momentum is also slower. ϴ is a measurement of the compensation that makes us the momentum flow rate that was lost due to the formation of the boundary layer. The momentum thickness is useful in determining the skin friction drag on a surface. [5] When deriving this equation it is assumed the flow is incompressible and steady. Momentum Thickness is an indication of Drag.
The purpose of this experiment was to see if a penny could hold more drops of salt water or tap water. It was found that a penny could hold an average of 22.3 drops of tap water and only 20.8 drops of salt water. These results are consistent with the hypothesis: If the salt concentration of water impacts the amount of water a penny holds, then the penny will hold less drops with salt water. While dropping the water onto the penny, it was observed that the water formed into a dome-like shape on the penny. It looked like the individual drops of water turned into one large drop of water. This was observed for both the tap and salt water. This happened due to the cohesion and surface tension of water. Cohesion simply means that water molecules are attracted to each other and want to cling together. Surface tension is the special term that is applied to the cohesion of water molecules.
A rapid oxidation process, which is a chemical chain reaction resulting in light and heat of varying intensities
Chemical dispersants pull apart oil particles that are suspended in water, reducing the oil slick to droplets that can be degraded by naturally occurring bacteria. When the chemicals are applied, dispersed oil is greatly less toxic. However, because the chemical properties of leaked oil will change over time, dispersants may lose their ability to break apart the oil. There are also concerns about the dispersants themselves , which can also be toxic and as a result it could be damaging the
Gummy bears are made of gelatin, starch and sugar. The cell is the basic unit of life and provides structure for our body. Cells are very important because they also take in nutrients from food and carry out important functions. The purpose of the experiment was to investigate the movements of liquids in and out of the gummy bear. In this case the liquids used were corn syrup, tap water and salt water. Molecules are in constant motion, and tend to move from areas of higher concentrations to lesser concentrations. Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration. The diffusion of water molecules through a selectively permeable
4. The flow velocity increases as the flow gets closer to the barrier wall and reduces as it moves away from the wall. This is because as the flow rate is constant (Conservation of mass) while the area of the flow cross section decreases when it gets closer to the barrier wall, the flow velocity increases. This is best understood by referring to the continuity equation,
The following hypothesis was made in regard to effect of the concentration gradient on the rate of diffusion: The higher the concentration gradient, the faster the rate of diffusion.
-The Reynolds number of this experiment was then calculated using equation (4) where c is the length of the aerofoil chord and is the dynamic viscosity of air.
When it comes to the topic of marsh funnel and measuring rheology, most of us will readily agree that it impossible to do so, where this agreement usually end, however, is one question of can the Marsh funnel builds rheograms. Whereas some are convinced that Marsh funnel may estimate the rheological properties, others maintain that marsh cannot do so.
When you pour oil into the water the oil separates from the water as bubbles and floats to the top and looks like a film on top of the water.
We believe that the method developed in this study would provide a convenient approach to fabricate complex collectors for producing ordered 2D or 3D nanofibrous structures.
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