Fluent inviscid solution

ashishtbm · May 28, 2013, 06:01

I am simulating a 2D cylinder under inviscid condition, but I am getting positive values of both lift and drag coefficient, while ideally both should be zero. I even did naca 0012 under inviscid condition but in this, lift coefficient is ok, but drag is still positive and is not reduced to zero. I want to know which model to be used and i what condition to to simulate ideal condition so that pressure drag becomes zero in my simulation?

sbaffini · May 28, 2013, 13:21

An ideal flow would give the results you expect. However, a numerically simulated inviscid flow carries all the numerical viscosity of the numerical method and it is impossible to avoid some numerical drag. For the cylinder case i expect no lift however, and it is possible that the flow field was not symmetric when you computed the lift.

yhy20081016 · June 21, 2014, 13:43

For the cylinder case, since there exists numerical viscosity, it is possible that the unsteady Karman vortex street occurs. If it happens, then the lift will not be zero.

May 28, 2013, 06:01	Fluent inviscid solution	#1
ashishtbm New Member Ashish Kumar Join Date: May 2013 Posts: 4 Rep Power: 13	I am simulating a 2D cylinder under inviscid condition, but I am getting positive values of both lift and drag coefficient, while ideally both should be zero. I even did naca 0012 under inviscid condition but in this, lift coefficient is ok, but drag is still positive and is not reduced to zero. I want to know which model to be used and i what condition to to simulate ideal condition so that pressure drag becomes zero in my simulation?

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May 28, 2013, 13:21		#2
sbaffini Senior Member Paolo Lampitella Join Date: Mar 2009 Location: Italy Posts: 2,192 Blog Entries: 29 Rep Power: 39	An ideal flow would give the results you expect. However, a numerically simulated inviscid flow carries all the numerical viscosity of the numerical method and it is impossible to avoid some numerical drag. For the cylinder case i expect no lift however, and it is possible that the flow field was not symmetric when you computed the lift.

June 21, 2014, 13:43		#3
yhy20081016 Member yehanyu Join Date: Mar 2012 Location: Beijing, China Posts: 48 Rep Power: 14	For the cylinder case, since there exists numerical viscosity, it is possible that the unsteady Karman vortex street occurs. If it happens, then the lift will not be zero.