3D cylinder and Vortex Street shedding issues

 Register Blogs Members List Search Today's Posts Mark Forums Read

 December 30, 2009, 19:57 3D cylinder and Vortex Street shedding issues #1 New Member   Joe Join Date: Nov 2009 Location: New York Posts: 4 Rep Power: 12 Hello everyone, I am a college student learning Fluent for a fluid mechanics class. as part of my final project for the class I am looking into Karman vortex streets of laminar flow past a cylinder. I have already gone through the tutorial in 2D and the outcome has been as expected. now i am trying to run the scenario in 3D but there is no sign of vortex shedding when I do. Cylinder diameter: 0.03m, Cylinder centered at 0,0,0 , cylinder extruded along the Z axis 0.03m in the positive and negative Z direction Fluid enclosure 0.4m in front, 2m on each of the sides and 1.7m behind the cylinder. fluent setup Laminar flow, Velocity inlet of 0.15 m/s in the X direction of 1, the standard air settings for density and viscosity. PISO, Least square method, standard pressure, 2nd order upwind momentum. my calculations show that with the Re=300 the time step is .034 with the St=0.2. the number of time steps is set to 1500 and 50 iterations per time step. I have also tried the setup at Re=150 and double the time step. (this is the same setup used for the 2D scenario which worked fine). I have done some research online regarding flow around a sphere which showed that shedding occurs at Re=300 and only after 480 seconds of the run. I have not waited that long since the Cl goes up to a point and then levels off and does not show the sinusoidal curve as seen in the 2D version. I have tried adjusting the mesh, geometry, Re numbers, going from least squared to Gauss green cell based. Still no luck seeing signs of shedding. I have a few more options based on research I have done which I plan on trying, but any help pointing me in the right direction would be great. I know this has been a long post, but have been trying to give as much information as I could. there is more to my project outside of just the vortex street, but I don't want to move ahead unless I get this part to work, taking a step by step approach. and for those interested, yes the semester is over but I took an incomplete so that i could finish the project. would rather be late and understand the material. If there is any more info needed, please let me know, I will supply. Thank you in advance and have a happy & healthy new years

 July 9, 2010, 16:35 #2 New Member   chandra sen vikram Join Date: Jul 2009 Posts: 4 Rep Power: 13 i am not able to attach file . i am intened to provide you for guidance.

 July 17, 2010, 11:19 #3 New Member   Ke peng Join Date: Jul 2009 Posts: 19 Rep Power: 13 You could refer to this paper: http://dspace.dsto.defence.gov.au/ds...-2232%20PR.pdf

 Tags 3d cylinder, fluent, vortex street