[student666]

Hi,

after including residual function into control dict, according to this tutorial
https://www.youtube.com/watch?v=LY4jUg3lOoE

functions 
{ 
//	#includeFunc PecletNo
	#includeFunc residuals
}

I can't plot residuals for U T h, but only ofr p and p_rgh-
looking at residuals.dat only coloumns for pressures are written, does someone know the reason why?

this is the residualDict:

#includeEtc "caseDicts/postProcessing/numerical/residuals.cfg"

fields (alphat  p  p_rgh  T  U h);

# Residuals    
# Time         	p              	p_rgh          	T              	Ux             	Uy             	h              
1              	7.66141540e-01	1.00000000e+00
2              	7.98974970e-01	1.83442730e-01
3              	6.27299870e-01	7.98917170e-02
4              	7.00095750e-01	3.86347270e-02
5              	5.92908140e-01	3.04990920e-02
6              	4.58467380e-01	2.39679380e-02
7              	4.45960730e-01	2.03891940e-02
8              	4.34298940e-01	1.80788340e-02
9              	3.52051730e-01	1.59621540e-02
10             	3.76240910e-01	1.44632730e-02

Thanks a lot

regards

[student666]

Hi,

I also tried the old way:

libs            ("libutilityFunctionObjects.so");
functions 
{residuals
{
    type            residuals;
    writeControl   timeStep;
    writeInterval  $deltaT;
    fields
    (  U  );
}
}

but this is the output on residuals.dat

# Residuals    
# Time         	Ux             	Uy             	Uz             
1              
2              
3              
4              
5              
6              
7              
8

any help?

[floquation]

If you have a look at the solver output (log file), do you see any velocity residuals?

If not, it is because "momentumPredictor" (or something like that) in "system/fvSolution" is off/false:
There are no velocity residuals if the velocity is not predicted (iterated separately) - then the velocity is fully determined by the pressure correction as to ensure continuity exactly.

I suspect this is why your residual-utility fails.

[student666]

Hi, thanks you're right, but in any case, even if I set to "yes" the moment-predictor, not all variables are plotted.
residualsDict:

#includeEtc "caseDicts/postProcessing/numerical/residuals.cfg"

fields (alphat  p  p_rgh  T  U h k omega phi);

residual.dat

# Residuals    
# Time         	alphat         	p              	p_rgh          	T              	Ux             	Uy             	h              	k              	omega          
1              	8.49454040e-01	1.00000000e+00	1.00000000e+00	9.99999860e-01	1.00000000e+00	9.39029660e-02
2              	9.60117560e-03	9.93457280e-01	4.13896110e-01	2.29865230e-01	6.02265870e-01	1.66618400e-02
3              	3.29224330e-02	7.58574770e-01	8.83426870e-01	1.25890060e-01	4.81928730e-01	1.03306770e-02

log file:

Time = 9

DILUPBiCG:  Solving for Ux, Initial residual = 0.021375153, Final residual = 0.00021156612, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.07626579, Final residual = 0.0012698228, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 0.029377071, Final residual = 0.0014589073, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 0.42919448, Final residual = 0.0039295721, No Iterations 4
time step continuity errors : sum local = 0.0043774316, global = 0.0012861574, cumulative = 0.0072015916
rho max/min : 1.1888231 1.1317888
DILUPBiCG:  Solving for omega, Initial residual = 0.011685404, Final residual = 0.00053581443, No Iterations 1
bounding omega, min: -23.944772 max: 617.83442 average: 20.391699
DILUPBiCG:  Solving for k, Initial residual = 0.019885726, Final residual = 0.00063162881, No Iterations 1
ExecutionTime = 7.55 s  ClockTime = 7 s

Any other suggestion?

If not, it is because "momentumPredictor" (or something like that) in "system/fvSolution" is off/false:
There are no velocity residuals if the velocity is not predicted (iterated separately) - then the velocity is fully determined by the pressure correction as to ensure continuity exactly.

Can you please give me more details about what does this means?

It's making me confusion.

Do you mean that velocity has no iteration (if "no" is set) and actual values for U, at current time step, are used inside pressure inner-loop of SIMPLE alghorithm?

Thanks

[floquation]

Originally Posted by student666

Hi, thanks you're right, but in any case, even if I set to "yes" the moment-predictor, not all variables are plotted.
residualsDict:

#includeEtc "caseDicts/postProcessing/numerical/residuals.cfg"

fields (alphat  p  p_rgh  T  U h k omega phi);

residual.dat

# Residuals    
# Time             alphat             p                  p_rgh              T                  Ux                 Uy                 h                  k                  omega          
1                  8.49454040e-01    1.00000000e+00    1.00000000e+00    9.99999860e-01    1.00000000e+00    9.39029660e-02
2                  9.60117560e-03    9.93457280e-01    4.13896110e-01    2.29865230e-01    6.02265870e-01    1.66618400e-02
3                  3.29224330e-02    7.58574770e-01    8.83426870e-01    1.25890060e-01    4.81928730e-01    1.03306770e-02

log file:

Time = 9

DILUPBiCG:  Solving for Ux, Initial residual = 0.021375153, Final residual = 0.00021156612, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.07626579, Final residual = 0.0012698228, No Iterations 1
DILUPBiCG:  Solving for h, Initial residual = 0.029377071, Final residual = 0.0014589073, No Iterations 1
GAMG:  Solving for p_rgh, Initial residual = 0.42919448, Final residual = 0.0039295721, No Iterations 4
time step continuity errors : sum local = 0.0043774316, global = 0.0012861574, cumulative = 0.0072015916
rho max/min : 1.1888231 1.1317888
DILUPBiCG:  Solving for omega, Initial residual = 0.011685404, Final residual = 0.00053581443, No Iterations 1
bounding omega, min: -23.944772 max: 617.83442 average: 20.391699
DILUPBiCG:  Solving for k, Initial residual = 0.019885726, Final residual = 0.00063162881, No Iterations 1
ExecutionTime = 7.55 s  ClockTime = 7 s

Any other suggestion?

So if I understand you correctly, turning on the momentumPredictor results in the velocity residual being plotted, whereas it does not get plotted when it's off?

I don't know about the other fields - I never used the utility you are using. Therefore, the only "other" suggestions I can give you are:
pyFoamPlotWatcher.py <-- I'm using this one.
The "old" way <-- This will work, but is more elaborate.

Originally Posted by student666

Can you please give me more details about what does this means?

It's making me confusion.

Do you mean that velocity has no iteration (if "no" is set) and actual values for U, at current time step, are used inside pressure inner-loop of SIMPLE alghorithm?

Thanks

If momentumPredictor is true, then the velocity is predicted before calculating the pressure.
In this case, there is a residual calculated for the velocity field.

If momentumPredictor is false, then the velocity from the previous timestep is taken instead.
In this case, there is no residual calculated for the velocity field. Evidently, one could still define a residual based on the new velocity and the old velocity - but it is simply not calculated afaik.

[student666]

Hi,

thanks for your reply.
About pyFoam, I already use it, but as new OF release has postProcess utility, I was digging into it to understand its capabilities.

Maybe a bug, maybe not....I'm thinking of make a bug report...

About momentum-predictor, thanks, I'm having a closer look to background theory.

Best regards.

Michele