Steady similation giving a periodic variation in temperature value at a probe point.

Sidharthkp · March 3, 2020, 06:06

Hi friends,
I am simulating flow and heat transfer in a concentric vertical annuls with inner cylinder heated and outer cylinder rotated. model details are:

solver- CFX
analysis type- steady state
Turbulence - Omega Reynolds stress with turbulent flux closure activated(no default values changed)
Buoyancy activated with buoyant turbulence (production and dissipation activated)
All high resolution schemes are selected.
Physical timescale is set(0.001s)

Initialized from a laminar solution, after a while, the temperature value near the exit of annulus shows a periodic variation as shwn in fig. attached..

Can anyone tell me what the reason could be.. Is it with my model or mesh(Using unstructered hexahedral mesh with smooth transition in mesh intensity is maintained(also attached)..

Please provide some input... (Please ask if more details needed)

Opaque · March 3, 2020, 12:51

Unfortunately, you have not shown the residual levels, nor the imbalances for the equation of interest.

without such information, it is all speculation.

ghorrocks · March 3, 2020, 17:19

I am guessing here (as Opaque states) but I suspect this FAQ is relevant: https://www.cfd-online.com/Wiki/Ansy...gence_criteria

March 3, 2020, 12:51		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,815 Rep Power: 32	Unfortunately, you have not shown the residual levels, nor the imbalances for the equation of interest. without such information, it is all speculation. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

March 3, 2020, 17:19		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,719 Rep Power: 143	I am guessing here (as Opaque states) but I suspect this FAQ is relevant: https://www.cfd-online.com/Wiki/Ansy...gence_criteria __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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