# Heat transfer of a cylinder in crossflow

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

 April 28, 2005, 03:26 Heat transfer of a cylinder in crossflow #1 aloha5i Guest   Posts: n/a Sponsored Links I am doing simulation of heat transfer of a circular cylinder in crossflow by using Fluent6.1. It is a typical problem. we can get a lot experimental data to check the results. It seems that in the laminar part before the seperation point the local Nusselt number(time averaged) is predicted well. However after the seperation point(In the wake region) the local nusselt number is a little bit far away from experimental results. Does anybody has good experience with this kind of simulation and has got very nice result? Thanks

 April 28, 2005, 17:44 Re: Heat transfer of a cylinder in crossflow #2 Mani Guest   Posts: n/a Is this laminar/turbulent, 2D/3D, i.e. what is the Reynolds number? If this is an unsteady case (Re>=47): How well do you predict the unsteady flow, besides heat transfer? Do you get good results on vortex shedding frequency, amplitudes of lift and drag oscillations, mean position and amplitude of oscillation of the separation point... ? How many cells do you have along the cylinder surface? What have you tried so far to improve your result? Grid convergence? Temporal resolution?

 April 28, 2005, 18:07 Re: Heat transfer of a cylinder in crossflow #3 aloha5i Guest   Posts: n/a Thanks Mani, I am doing 2-D simulation. The Reynolds number is around 5300. The fulid is air. The Strouhal number at Re = 5300 is around 0.2. My simulation predicted vortex shedding frequency not bad. The deviation is around 10%. The oscillation of drag coefficient is between 1.6 and 1.3. The oscillation of lift coefficient is between 1.2 and -1.2. I don't know how to get the seperation point directly from fluent. By analysing the local nusselt number, the lowest point should be seperation point. so the mean point should be near 90 degree from stagnation point in my result. The diameter of the circular cylinder is 0.02m. There are 124 nodes along the surface of the cylinder. I tried to simulate this problem by using different grid density. The solution is almost mesh independent which means when i increased the grid number the average nusselt number keep as a constant. There is the effect of fluid properties on heat transfer between fluid and the cylinder. In order to eliminate the effect from the fluid properties, the constant properties value at film temperature are configured in the CFD calculation. Actually I tried to simulate with material properties at bulk temperature also. there is almost no changes in average nusselt number and local nusselt number. This is almost how far I am in this calculation. Any suggestions and ideas will be highly appriciated.

 May 5, 2005, 05:11 Re: Heat transfer of a cylinder in crossflow #5 aloha5i Guest   Posts: n/a Thanks a lot, Mani, Your ideas help me a lot. I am trying to make more nodes on around the cylinder. Another reason for doing this is that the Drag Coefficient is also not good. The result of Cd is around 1.6(Time averaged). However, as we know at Re = 5000, the drag coefficient should be about 1.2. Now I have to no time to try 3-D simulation because I have to submit the report. I will do it later. For me It's quite interesting. Thanks again.

 May 5, 2005, 09:55 Re: Heat transfer of a cylinder in crossflow #6 diaw Guest   Posts: n/a For an interesting look at optimised meshes, take a look at , where they benchmark various schemes for the cylinder example... This could help you to concentrate your mesh refinement where you can maximise the return... diaw...

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Attesz CFX 7 January 5, 2013 04:32 Dav_Mechanical FLUENT 1 October 5, 2011 15:16 enigma Main CFD Forum 2 November 1, 2009 23:53 B.Simon CFX 3 October 28, 2008 19:53 Mark CFX 6 November 15, 2004 16:55