Cover Page for Lab Report – Group Portion
Introduction to Computational Fluid Dynamics
Prepared by Professor J. M. Cimbala, Penn State University
Latest revision: September 18, 2014 by Corey Breznak, Guangsheng Zhang and Prof. Chao-Yang Wang
Name 1:
___________________________________________________
Name 2:
___________________________________________________
Name 3:
___________________________________________________
[Name 4:
___________________________________________________ ]
Date:
_______________________________
Section number:
ME 325._____
Group #_____
Score (For instructor or TA use only):
Lab experiment and results, plots, tables, etc. - Procedure portion
Discussion
Neatness & grammar
TOTAL
Comments (For instructor or TA use only):
_____ / 45
_____ / 15
_____ / 10
______ / 70
Procedure and Presentations of Results
A.
Flow over a Cylinder – Two Dimensional Case
In this exercise, the flow of a fluid over a cylinder will be studied using the CFD code FLUENT in ANSYS
Workbench. A step by step tutorial can be found in the Appendix of Precalculation file. Follow these instructions
carefully.
(5)
1. Print out a copy of the velocity contour plot, the static pressure contour plot and the velocity vectors plot. Make sure
all plots are large enough to see important details.
See Figures_____.
(5)
2. Print out a copy of all the forces acting on the cylinder, as described in the tutorial.
See Table_____.
(5)
3. Calculate the drag coefficient Cd of the flow over the cylinder. Show all work.
(5)
4. Calculate the Reynolds number of the flow over the cylinder. Show all work.
(4)
5. As stated in the tutorial, change the boundary conditions to Symmetry.
Print out a copy of the new velocity and pressure contour plots.
See Figures_____.
(3)
6. Print out a copy of all the forces acting on the cylinder for the new boundary condition.
See Table_____.
(3)
7. Calculate the new drag coefficient Cd of the flow over the cylinder. Show all work.
B.
Calculation of a Laminar Flat Plate Boundary Layer
In the final exercise, you will generate your own computational domain and mesh, specify and apply boundary
conditions, and iterate towards a CFD solution. Detailed instructions for this exercise are found on the Internet at Professor
Cimbala’s web site: www.mne.psu.edu/cimbala, then select Teaching, then Professor Cimbala’s Learning Modules &
Tutorials, & then, ANSYS Workbench Tutorials . Finally, locate the Tutorial called Flat Plate Boundary Layer Flow.
1.
(5)
2.
3.
4.
(10)
5.
Generate the grid using ANSYS following the instructions on the web page. Read these instructions slowly and
carefully. You may find it easier to use the printed copy that should be in the lab at the computer station.
Calculate the flow using FLUENT, following the instructions on the web page for the laminar case.
Make printouts of the X-Y plots that you generated in FLUENT.
See Figures ______.
Locate and open the velocity profile text file you created in FLUENT – the laminar boundary layer profile at the
outlet (Note: outlet is at 0.5 m from leading edge of flat plate; it is at x=0.6 in the ANSYS coordinate system).
Copy and paste the data into Excel.
Plot the boundary layer profile in nondimensional (Blasius) similarity coordinates. On the same plot, include the
published Blasius boundary layer profile for comparison (see Precalculations). In the space below, show some
sample calculations. Make sure the figure is labeled and numbered, and attach it to your report.
Sample calculations:
See Figure ______ .
Discussion
(5)
1.
Lab 4, Drag on Spheres, was a (relatively) high Reynolds numbers experiment. It was found that the form drag
(i.e. pressure drag) was the dominating contributor to the drag force. However, in Part A, the Reynolds number
was found is relatively low (on the order of 10). Contrast a low Re flow with a high Re flow in terms of the
magnitudes of inertial (pressure) and viscous forces.
(5)
2.
When changing the boundary conditions to Symmetry, what differences do you find in the velocity and pressure
contours? Discuss any major differences in drag coefficient.
(5)
3.
For the laminar flat plate boundary layer case, does the measured nondimensional velocity profile agree well with
the Blasius profile? If not, discuss possible reasons for the discrepancies. Which solution is more accurate, the
Blasius similarity solution or the CFD calculation? Discuss.