Lab 1 Worksheet Part 1 and Part 2

Engineering 1282.02H

Spring, 2016

Jack Canaday

Justin Iovino

DMG 12:40

Date of Experiment: 2/22/16

Date of Submission: 2/26/16

Part 1 Coarse Mesh:

1. Insert screen shot of your goals plot below:

Figure 1: Plot of Max and Min Velocities in Channel.

2. Insert screen shot of your pressure contour surface plot below:

Figure 2: Pressure Contour

3. Insert screen shot of your Velocity Contours (z = 0.010 m) below:

Figure 3: Velocity Contours at z=.010m

4. Insert a screen shot of your Velocity Vectors (z = 0.010 m) below:

Figure 4: Velocity Vectors at z=.010m

5. Insert a screen shot of your Flow Trajectories below:

Figure 5: Flow Trajectories.

Fine Mesh:

6. Insert a screen shot of your Goals Plot below:

Figure 6: Refined Mesh Goals Plot

7. Insert screen shots of your 2-D velocity Contours below (z = 0.010m, -0.01240m, -0.01245m, -0.01250m, last 3 can be combined in one screenshot):

Figure 7: Refined Mesh Velocity Contour at z=.010m

Figure 5: Refined Mesh Velocity Contour at z=-.01240m, z=-.01245, z=-.01250m

8. Insert a screen shot of your 3-D Velocity Contours below:

Figure 8: 3D Velocity Contour at z=.010m

9. Insert a screen shot of your Sheer Stress Contours below:

Figure 9: Shear Stress along bottom of channel.

10. Discuss the flow profiles you achieved in this part of the lab. Are the results similar to what you would expect based on your knowledge of fluid mechanics? Why or why not? Consider laminar vs. turbulent flow, the no-slip condition, as well as any other concepts you think are important.

Yeah. These flow profiles make sense. The values represent clearly that laminar flow is taking place. The no-slip condition is also accounted for as the velocity on the edges of the channel (as seen in Figure 7 and 8) is zero. It’s also clear from the velocity trajectories plot that the flow is laminar.

11. Discuss the differences you see between the results of the coarse and fine meshes. How do the flow velocities and profiles compare? Which mesh seems to do a better job of replicating the flow profile we would expect in the channel? (What known condition does one of the meshes violate, based on the flow profile produced?)

The flow velocities and profiles are far more detailed and accurate with the finer mesh. This can be attributed to the greater amount of precision that is associated with having a finer mesh. It appears that as the computer is given more data points with a finer mesh it is able to create more accurate / detailed flow simulations. The course mesh violates the no-slip condition because as shown in Figure 3 the velocity at the bottom of the channel is the same as the velocity in the center when in reality the velocity at the bottom of the channel should be zero in accordance with the no-slip condition.

12. Based on the results from this part of the lab, how important is establishing a quality mesh before running your flow simulation? What could happen if the mesh is too course? What drawbacks might be present when using a fine mesh compared to a course mesh?

Establishing a quality mesh is essential to running an accurate flow simulation. If the mesh is too course then the quantities determined by SolidWorks will have an unnecessary amount of error in them. The drawback of using a fine mesh comes in the increased amount of computer processing power necessary to draw the mesh. Because of this, the finer the mesh, the slower SolidWorks will be able to run iterations and calculate the quantities. A fine line between accuracy and efficiency should be reached when choosing a mesh for our chip.

13. After completing this part of the lab, how do you plan to assign a proper mesh for your custom chip design?

I plan to assign a mesh that can provide me with good results but not drastically slow down my computations. I will probably use a mesh with values similar to the values found in the finer mesh we used in this lab as it offered a good degree of accuracy and didn’t take too long.

Part 2 1. Insert screen shot of your mesh below:

Figure 6: Screenshot of Initial Mesh

2. Insert screen shot of your goals plot below:

Figure 7: Screenshot of Goals Plot

3. Complete the table below with the results from your flow simulation:

Table 1: Calculated Values of SolidWorks

Parameter Value Max Velocity .0818604 m/s

Delta (over last 5 iterations) 5.803e-7 m/s Average Velocity .08186 Max Shear Stress 2.55

4. Insert screen shot of your Velocity Simulation (flow trajectories) below:

Figure 8: Screenshot of Flow Trajectories

5. Insert a screen shot of your Velocity Contours (lateral) below:

Figure 9: Screenshot of Lateral Velocity Contours

6. Insert a screen shot of your Velocity Contours (transverse) below:

Figure 10: Screenshot of Transverse Velocity Contours

7. Insert a screen shot of your Pressure Contour below:

Figure 11: Screenshot of Pressure Contour.

8. Insert a screen shot of your Sheer Stress Contours below:

Figure 12: Screenshot of Sheer Stress Contour

9. Use your fluid mechanics program to simulate the flow simulation performed in this part of the lab. The dimensions of the complex channel you used for this part of the lab are below:

Length 22.30 mm Width 0.33 mm Height 0.13 mm

Below are the flow parameters:

Pressure Head (ΔP) Dynamic Viscosity (µ)

Density (ρ)

1000 Pa 0.0010014 Pa·s 998.16 kg/m3

Fill out the table below with the results of the SolidWorks flow simulation (from question 3) and the results from the fluid mechanics program:

Table 2: Caption goes here.

Parameter SolidWorks Fluid Mechanics Program Average Velocity .0818604 m/s .063066 m/s Max Shear Stress 2.55 Pa 2.23 Pa

How do the two results compare? What discrepancies, if any, are present? Use your knowledge of the assumptions of both simulations to think of potential causes of any differences. Our values were different from the values calculated within Solidworks by a small margin (.02 m/s and .3 Pa respectively). This difference can be attributed to the assumptions within our program that the x axis doesn’t affect the flow rate. Our program also goes off the assumption that flow within the channel will be laminar whereas SolidWorks was calculating based on a laminar/turbulent flow which could potentially modify numbers.

10. Briefly discuss what each of the following plots shows you in regards to the flow in the channel simulation. Your discussion of each plot should indicate your understanding of the basic fluid mechanics principles we’ve learned in class. Be sure to address why the contours can change near the walls of the channel, where applicable.

Lateral velocity contours: The lateral velocity contours indicates that the velocity of flow in the middle of the channel is greatest. This can be attributed to the fact that the velocity profile a rectangular channel is parabola with the greatest values in the center of the channel.

Transverse velocity contours: The transverse velocity contour indicates the velocity of flow in the middle of the channel and at the height at the middle of the channel is highest. It also illustrates how velocity is slowest near the edges of the channels. These properties can also be attributed to the parabola curve of the velocity profile in a rectangular channel. Pressure contour: The pressure contour indicates that pressure falls as we travel down the channel. This can be explained by the fact that the inlet flow port has a pressure of 1000 Pa greater than that at the outlet port. This decrease of pressure across the channel is the reason why fluid flows through the channel at the mathematically modeled velocities we have determined.

11. Shear stress contour: What effect, if any, do the inlet and outlet areas have on the flow? What does this tell you about the importance of entrance length? How will this affect your chip design and/or experimental procedure? Reference any corresponding figures which support your claim.

They have no effect on the flow after a short period – this can be seen as the sheer stress contour reaches a consistent hue over the entire channel after a short period of color change. This tells us that entrance length is not an important factor in the design of our chip as long as the channel is long enough for the sheer stress to reach that consistent value. In designing our channel we will try to make our entrance length short enough so that we can gather data within each channel when the sheer stress has reached the value consistent for the channel.