shadding vortex
Hi!
i'm a cfd newbie and i'm trying to solve a tipical cfd problem: catching shedding vortex (shown in the figure below) generated by a steady flow around a circle (2D) with Fluent http://img11.imageshack.us/img11/294...hedding.th.jpg i'm trying to solve it with a keps model (unsteady analisys). for the mesh i use a boundary layer around the circle and a triangular growing size mesh all over, (more thick in the tail) is this correct? and about the wall condition, do i have to use one? thank you very much! 
1 Attachment(s)
here one example for laminar flow:
Attachment 6437 
thanks, but is not i was looking for....
now i undertstand that i can obtain the phenomenou by chosing a different viscous turbolence model according to the reynolds number... is it correct? thanks 
Quote:
Quote:

yes! thank you very much!
i resolved the case with keps model, and now i'm trying to change their values (k and eps) to understand how they affect the phenomenou... but i don't really understand... moreover i would know how to choose this parameters 
k and eps are fixed (you impose a specific turbulent flowfield given by Re >> check litterature)
So you are not supposed to change their values as you are not supposed to change the inlet velocity (for a given Re) 
i use fluent and with this software i have to specify the velocity at the inlet, k and eps (how choose them?)... i calculate the reynolds manually..

there are formulas for k and eps.
Check online help chapter 7.2.2 "Determining Turbulence Parameters" 
what is the different between the steady and unsteady command?
i tried to solve a simple 2d problem of a beam section: with the steady solution a keps viscous model sometimes i cath the oscillation of the lift coefficient, but with the unsteady keps i don't reach the same results... i don't understand why this happens, because in general the flow should be unsteady.... 
Quote:
In unsteady solver, the oscillations are unsteady oscillations with respect of time (and not iterations as in steady solver) 
Why are you trying a steady state solution ??????? Flow over a cylinder is not a steady state problem............ It is a transient case problem.

All times are GMT 4. The time now is 20:47. 