Fluctuating residuals

tichaona · February 7, 2012, 11:27

Dear collegues

I am new to fluent. I have modeled a room 8m length by 4m. The room has 2 windows and 1 door on windward side and 2 windows and 1 door on leeward. I have also modeled the atmospheric air as an enclosure of the room. The atmospheric air enclosure measures 252m (width) by 256m (length) by 105m (height). I am using polyhedra mesh. I am running steady flow simulation. The energy equation is off. The solution has converged after 77 iterations. I am having fluctuating residuals and the continuity and epslon residuals are fluctuating above 10e-3. The others are fluctuating below. What causes these fluctuations and how can I solve the problem. May you please assist with regard to the above.

Thank you in advance for any contributions.

Vitaly · February 7, 2012, 14:49

Hi,

What do you mean by "fluctuating residuals?" Are they just oscilating around a single value that is greater than 10^-3? That's normal, you might just need to relax the solution a little bit (take smaller guessing steps).

What is your criteria for convergence?

February 7, 2012, 11:27	Fluctuating residuals	#1
tichaona New Member tichaona Join Date: Dec 2011 Location: South Africa Posts: 13 Rep Power: 14	Dear collegues I am new to fluent. I have modeled a room 8m length by 4m. The room has 2 windows and 1 door on windward side and 2 windows and 1 door on leeward. I have also modeled the atmospheric air as an enclosure of the room. The atmospheric air enclosure measures 252m (width) by 256m (length) by 105m (height). I am using polyhedra mesh. I am running steady flow simulation. The energy equation is off. The solution has converged after 77 iterations. I am having fluctuating residuals and the continuity and epslon residuals are fluctuating above 10e-3. The others are fluctuating below. What causes these fluctuations and how can I solve the problem. May you please assist with regard to the above. Thank you in advance for any contributions.

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February 7, 2012, 14:49		#2
Vitaly Member Vitaly Join Date: Jan 2012 Posts: 32 Rep Power: 14	Hi, What do you mean by "fluctuating residuals?" Are they just oscilating around a single value that is greater than 10^-3? That's normal, you might just need to relax the solution a little bit (take smaller guessing steps). What is your criteria for convergence?