# Unsteady Laminar Flow Around a circular cylinder

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 LinkBack Thread Tools Display Modes
 December 29, 2007, 11:44 Unsteady Laminar Flow Around a circular cylinder #1 Mehmet Sonmez Guest   Posts: n/a Hi, I am investigating the behaviour of liquid water around a circular cylinder. Reynolds number is 178, and the velocity is 0.0008942m/s. But I couldn't get the velocity contour as it should be. Here is the image of how it should be. http://img186.imagevenue.com/img.php..._122_425lo.JPG And this is what I got(It is definitely wrong) http://img11.imagevenue.com/img.php?..._122_930lo.JPG Can anybody help me? I chose unsteady solver and laminar for viscous. Time Step Size, Number of Step Size, Max Iter. per Time Step, have they any impact on the result?

 December 29, 2007, 12:55 Re: Unsteady Laminar Flow Around a circular cylind #2 Ramesh.K Guest   Posts: n/a Hi, when u are solving unsteady flow time step plays a major role in predicting the physics of the flow. Timestep is calculated based on v=del(x)/del(t) where del t should be ur time step. u can see it in fluent manual how to calculate the time step. if accurate time step is not specified the solution will not be correct. bye

 December 29, 2007, 15:03 Re: Unsteady Laminar Flow Around a circular cylind #3 Mehmet Sonmez Guest   Posts: n/a Thank you very much, Ramesh.K

 December 31, 2007, 01:13 Re: Unsteady Laminar Flow Around a circular cylind #4 Sham Guest   Posts: n/a Ramesh is right that time step is very important. In choosing a time step, try to keep the cell CFL (Courant) number to be below 1 near the cylinder. Also, you have to run it long enough to be able to get some vortex shedding and may be need to introduce some perturbation to stimulate shedding. Sham.

 January 3, 2008, 06:28 Re: Unsteady Laminar Flow Around a circular cylind #5 vinse Guest   Posts: n/a hi, How to calculate the number of time step per iterations in an unsteady problem. thanks in advance

 January 3, 2008, 06:33 Re: Unsteady Laminar Flow Around a circular cylind #6 Sham Guest   Posts: n/a In my opinion thats does not really matter as long as your time step size is small enough. In m simulation, it takes about 5 iterations per time step.

 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 ksaat FLUENT 0 April 20, 2011 11:33 JSoares FLUENT 1 April 12, 2011 02:37 Senthilkumar Main CFD Forum 2 April 19, 2009 23:18 Mirek Kabacinski FLUENT 0 July 23, 2003 18:40 M. S. GUEROUACHE Main CFD Forum 0 October 1, 1998 10:51

All times are GMT -4. The time now is 10:25.

 Contact Us - CFD Online - Top