Computational Fluid Dynamics (CFD) Homework
Jason Oakley, Spring, 2007
Minor edits by Scott Sanders
You should make a report including the items in boldface.
1. Go through the u-bend example if you haven’t already.
2. Conduct a simulation for a geometry with the same square cross-section pipe (side is 75.5 mm), a 300 mm horizontal inlet run, a 90 degree bend (inner radius 75 mm, outer radius 150.5 mm) to the vertical, and then a 300 mm vertical run. Use an inlet velocity of 7.5 m/s, and use the same Fluent settings for solver, residuals, etc, EXCEPT, for the solution initialization, specify the x velocity as 1 m/s and also, the y velocity as 1 m/s.
3. A) Plot and include in your hardcopy report the velocity distribution at the bend exit (shown by a dashed line above). Use the same method we used for the u-bend which found the velocity distribution at the bend halfway-point. B) Compare this to the velocity distribution at the bend exit given in your HW prob 4.26 where Vmax=2*Vmin. Describe your findings. C) What is Vmax? D) What is Vmin? E) Is the velocity distribution linear, parabolic, other?
4. Under define>boundary conditions, select the velocity inlet, and in the right column under type, choose pressure_inlet Select set, and enter 83,675 for the “Gauge Total Pressure (pascal)”, and close. Re-initialize the domain to Vx=1 m/s, Vy=1 m/s. Run the simulation. A) What is the force on the bend in the x-direction (same method used in u-bend example, and don’t forget to multiply the answer by the square pipe depth, 75.5 mm). B) How does this value compare with the force on the bend as calculated using the control volume analysis at http://ecow.engr.wisc.edu/cgi-bin/get/me/363/sanders/thissemest/examplepro/4-78.pdf? C) plot the velocity distribution at the bend exit and and compare with the velocity distribution used for the calculation used in HW prob 4.78 and explain any differences. D) plot the velocity vector field as a 2-D image.